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_______________general description the MAX4223?ax4228 current-feedback amplifiers combine ultra-high-speed performance, low distortion, and excellent video specifications with low-power oper- ation. the MAX4223/max4224/max4226/max4228 have a shutdown feature that reduces power-supply current to 350? and places the outputs into a high- impedance state. these devices operate with dual sup- plies ranging from ?.85v to ?.5v and provide a typical output drive current of 80ma. the MAX4223/ max4225/max4226 are optimized for a closed-loop gain of +1 (0db) or more and have a -3db bandwidth of 1ghz, while the max4224/max4227/max4228 are compensated for a closed-loop gain of +2 (6db) or more, and have a -3db bandwidth of 600mhz (1.2ghz gain-bandwidth product). the MAX4223?ax4228 are ideal for professional video applications, with differential gain and phase errors of 0.01% and 0.02? 0.1db gain flatness of 300mhz, and a 1100v/? slew rate. total harmonic distortion (thd) of -60dbc (10mhz) and an 8ns settling time to 0.1% suit these devices for driving high-speed analog-to-digital inputs or for data-communications applications. the low- power shutdown mode on the MAX4223/max4224/ max4226/max4228 makes them suitable for portable and battery-powered applications. their high output impedance in shutdown mode is excellent for multiplex- ing applications. the single MAX4223/max4224 are available in space- saving 6-pin sot23 packages. all devices are available in the extended -40? to +85? temperature range. ________________________applications adc input buffers data communications video cameras video line drivers video switches video multiplexing video editors xdsl drivers rf receivers differential line drivers ____________________________features ? ultra-high speed and fast settling time: 1ghz -3db bandwidth (MAX4223, gain = +1) 600mhz -3db bandwidth (max4224, gain = +2) 1700v/? slew rate (max4224) 5ns settling time to 0.1% (max4224) ? excellent video specifications (MAX4223): gain flatness of 0.1db to 300mhz 0.01%/0.02 dg/dp errors ? low distortion: -60dbc thd (f c = 10mhz) 42dbm third-order intercept (f = 30mhz) ? 6.0ma quiescent supply current (per amplifier) ? shutdown mode: 350? supply current (per amplifier) 100k output impedance ? high output drive capability: 80ma output current drives up to 4 back-terminated 75 loads to ?.5v while maintaining excellent differential gain/phase characteristics ? available in tiny 6-pin sot23 and 10-pin ?ax packages MAX4223?ax4228 1ghz, low-power, sot23, current-feedback amplifiers with shutdown ________________________________________________________________ maxim integrated products 1 v ee in- in+ 1 6 v cc 5 shdn out MAX4223 max4224 sot23-6 top view 2 3 4 _________________pin configurations 19-1230; rev 2a; 6/97 part MAX4223 eut-t MAX4223esa -40? to +85? -40? to +85? temp. range pin- package 6 sot23 8 so evaluation kit available ______________ordering information _____________________selector guide pin configurations continued at end of data sheet. ordering information continued at end of data sheet. for free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 for small orders, phone 408-737-7600 ext. 3468. sot top mark aaad 10 ?ax, 14 so 8 so 10 ?ax, 14 so 8 so 6 sot23, 8 so 6 sot23, 8 so pin- package yes no yes no yes yes shut- down mode 2 2 2 2 1 1 amps per pkg. 2 2 max4227 max4228 1 part 1 max4225 max4226 2 1 MAX4223 max4224 min. gain
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics (v cc = +5v, v ee = -5v, shdn = 5v, v cm = 0v, r l = , t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. supply voltage (v cc to v ee ) .................................................. 12v analog input voltage ....................... (v ee - 0.3v) to (v cc + 0.3v) analog input current ........................................................ 25ma shdn input voltage ......................... (v ee - 0.3v) to (v cc + 0.3v) short-circuit duration out to gnd ........................................................... continuous out to v cc or v ee ............................................................ 5sec continuous power dissipation (t a = +70 c) 6-pin sot23 (derate 7.1mw/ c above +70 c) ............. 571mw 8-pin so (derate 5.9mw/ c above +70 c) ................... 471mw 10-pin max (derate 5.6mw/ c above +70 c) ............ 444mw 14-pin so (derate 8.3mw/ c above +70 c) ................. 667mw operating temperature range ........................... -40 c to +85 c storage temperature range ............................. -65 c to +150 c lead temperature (soldering, 10sec) ............................. +300 c conditions 0.5 4 units min typ max symbol parameter mv 0.5 5 v os input offset voltage 2 10 input bias current (positive input) 7 t a = t min to t max a 15 t a = +25 c 45 r in- input resistance (negative input) k 700 r in+ input resistance (positive input) 55 61 inferred from cmrr test v 2.5 3.2 v cm input common-mode voltage range inferred from psrr test v 2.85 5.5 v cc /v ee v cm = 2.5v operating supply voltage range 68 74 db 50 cmrr common-mode rejection ratio v cc = 2.85v to 5.5v, v ee = -2.85v to -5.5v db 63 psrr power-supply rejection ratio shutdown mode ( shdn = 0v) ma 0.35 0.55 r l = 50 i sy quiescent supply current (per amplifier) normal mode ( shdn = 5v) 6.0 9.0 v 2.5 2.8 v out output voltage swing v out = 2.5v m 0.3 0.8 t r open-loop transresistance v out = 2.5v ma 60 80 i out output current (note 2) 0.7 1.5 r l = short to ground ma 140 i sc short-circuit output current v 0.8 v il shdn logic low 4 20 t a = +25 c a 4 25 i b+ t a = +25 c t a = t min to t max t a = +25 c t a = t min to t max r l = r l = 50 v 2.0 v ih shdn logic high 6 t a = t min to t max MAX4223/max4224 MAX4223/max4224 max4225?ax4228 v/ c 2 tcv os input offset voltage drift max4225?ax4228 t a = t min to t max 30 input bias current (negative input) 35 i b- t a = +25 c MAX4223/max4224 max4225?ax4228 MAX4223/max4224 max4225?ax4228
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown _______________________________________________________________________________________ 3 dc electrical characteristics (continued) (v cc = +5v, v ee = -5v, shdn = 5v, v cm = 0v, r l = , t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) ac electrical characteristics (v cc = +5v, v ee = -5v, shdn = 5v, v cm = 0v, a v = +1v/v for MAX4223/max4225/max4226, a v = +2v/v for max4224/max4227/ max4228, r l = 100 , t a = +25 c, unless otherwise noted.) (note 4) 10 100 conditions 25 70 units min typ max symbol parameter a i il /i ih shdn input current shdn = 0v or 5v shdn = 0v, v out = -2.5v to +2.5v (note 3) shutdown mode output impedance k max4224/7/8 MAX4223/5/6 60 200 100 300 MAX4223/5/6 0.1 v out = 2v step max4224/7/8 thd 850 1100 1.5 total harmonic distortion r l = 1k 1400 1700 250 -65 v out = 4v step 625 800 db conditions gain peaking v out = 2vp-p mhz 330 bw ls large-signal bandwidth MAX4223/4/6/8 v out = 2v step r l = 100 MAX4223/5/6 MAX4223/5/6 s 2 0.02 t on turn-on time from shutdown shdn = 0v, f = 10mhz, MAX4223/4/6/8 db 65 off isolation r l = 150 (note 6) 0.01 degrees 0.01 v cc , v ee = 0v to 5v step ns 100 t up MAX4223/4/6/8 power-up time r l = 150 (note 6) % 0.02 dg differential gain error ns 300 t off turn-off time to shutdown f = 30mhz, r s = 50 max4225/6 -60 325 600 dbc -61 MAX4223/5/6 750 1000 max4224/7/8 -78 max4224/7/8 dp differential phase error max4224/7/8 max4224/7/8 MAX4223/5/6 MAX4223/5/6 rising edge MAX4223/5/6 v out = 2vp-p, f c = 10mhz max4224/7/8 MAX4223/5/6 1.0 falling edge 1100 1400 v/ s sr slew rate (note 5) max4224/7/8 1.5 units min typ max symbol parameter ns max4224/7/8 t r , t f rise and fall time MAX4223/5/6 MAX4223/5/6 max4224/7/8 MAX4223/5/6 v out = 20mvp-p mhz max4224/7/8 bw 0.1db bandwidth for 0.1db gain flatness (note 5) v out = 20mvp-p -72 max4227/8 -68 8 db ns 5 x talk t s settling time to 0.1% crosstalk mhz bw -3db small-signal bandwidth (note 5) max4224/7/8
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 4 _______________________________________________________________________________________ note 1: the max422_eut is 100% production tested at t a = +25 c. s pecifications over temperature limits are guaranteed by design. note 2: absolute maximum power dissipation must be observed. note 3: does not include impedance of external feedback resistor network. note 4: ac specifications shown are with optimal values of r f and r g . these values vary for product and package type, and are tabulated in the applications information section of this data sheet. note 5: the ac specifications shown are not measured in a production test environment. the minimum ac specifications given are based on the combination of worst-case design simulations along with a sample characterization of units. these minimum specifications are for design guidance only and are not intended to guarantee ac performance (see ac testing/ performance ). for 100% testing of these parameters, contact the factory. note 6: input test signal: 3.58mhz sine wave of amplitude 40ire superimposed on a linear ramp (0ire to 100ire). ire is a unit of video signal amplitude developed by the international radio engineers. 140ire = 1v. note 7: assumes printed circuit board layout similar to that of maxim? evaluation kit. ac electrical characteristics (continued) (v cc = +5v, v ee = -5v, shdn = 5v, v cm = 0v, a v = +1v/v for MAX4223/max4225/max4226, a v = +2v/v for max4224/max4227/ max4228, r l = 100 , t a = +25 c, unless otherwise noted.) (note 4) __________________________________________ t ypical operating characteristics (v cc = +5v, v ee = -5v, r l = 100 , t a = +25 c, unless otherwise noted.) 4 3 -6 1 100 1000 10 MAX4223 small-signal gain vs. frequency (a vcl = +1) -4 -5 MAX4223-01 frequency (mhz) gain (db) -2 -3 0 -1 2 1 v in = 20mvp-p so-8 package r f = 560 w sot23-6 r f = 470 w 4 3 -6 1 100 1000 10 MAX4223 small-signal gain vs. frequency (a vcl = +2/+5) -4 -5 MAX4223-02 frequency (mhz) normalized gain (db) -2 -3 0 -1 2 1 v in = 20mvp-p a v = +2v/v r f = r g = 200 w a v = +5v/v r f = 100 w r g = 25 w 4 3 -6 1 100 1000 10 MAX4223/max4225/max4226 large-signal gain vs. frequency (a vcl = +1) -4 -5 MAX4223-03 frequency (mhz) gain (db) -2 -3 0 -1 2 1 a v = +1v/v r f = 560 w v out = 2vp-p parameter symbol min typ max units input capacitance (note 7) c in 0.8 42 third-order intercept ip3 36 1.0 dbm so-8, so-14 packages f = 30khz f z = 30.1mhz sot23-6, 10-pin max packages 0.3 0.3 conditions 2 output impedance z out 20 1db gain compression 2 dbm f = 10khz f = 10khz 3 input noise current density i n +, i n - 20 pa/ hz f = 10khz input noise voltage density pf e n nv/ hz f = 10khz MAX4223/5/6 max4224/7/8 -61 spurious-free dynamic range sfdr -62 db f = 10khz MAX4223/5/6 max4224/7/8 in+ in- pin to pin pin to gnd pin to pin pin to gnd
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown _______________________________________________________________________________________ 5 4 3 -6 1 100 1000 10 max4224 small-signal gain vs. frequency (a vcl = +2) -4 -5 MAX4223-04 frequency (mhz) normalized gain (db) -2 -3 0 -1 2 1 v in = 20mvp-p so-8 package r f = r g = 470 w sot23-6 package r f = r g = 470 w 4 3 -6 1 100 1000 10 max4224 small-signal gain vs. frequency (a vcl = +5/+10) -4 -5 MAX4223-05 frequency (mhz) normalized gain (db) -2 -3 0 -1 2 1 v in = 20mvp-p a vcl = +5v/v r f = 240 w r g = 62 w a vcl = +10v/v r f = 130 w r g = 15 w 4 3 -6 1 100 1000 10 max4224/max4227/max4228 large-signal gain vs. frequency (a vcl = +2) -4 -5 MAX4223-06 frequency (mhz) normalized gain (db) -2 -3 0 -1 2 1 a vcl = +2v/v r f = r g = 470 w v out = 2vp-p 4 3 -6 1 100 1000 10 max4225/max4226 small-signal gain vs. frequency (a vcl = +1) -4 -5 MAX4223-07 frequency (mhz) gain (db) -2 -3 0 -1 2 1 v in = 20mvp-p a vcl = +1v/v r f = 560 w 0.4 0.3 -0.6 0.1 10 100 1 max4227/max4228 gain matching vs. frequency (a vcl = +2) -0.4 -0.5 MAX4223-10 frequency (mhz) normalized gain (db) -0.2 -0.3 0 -0.1 0.2 0.1 v in = 20mvp-p a vcl = +2v/v r f = r g = 470 w 10 100 max4225/max4226 gain matching vs. frequency (a vcl = +1) MAX4223-08 frequency (mhz) gain (db) 1 amplifier a 0.4 0.3 -0.6 -0.4 -0.5 -0.2 -0.3 0 -0.1 0.2 0.1 v in = 2omvp-p a vcl = +1v/v r f = 560 w amplifier b 0 -10 -100 1 100 1000 10 max4225/max4226 crosstalk vs. frequency -80 -90 MAX4223-11 frequency (mhz) crosstalk (db) -60 -70 -40 -50 -20 -30 r s = 50 w v out = 2vp-p 0 -10 -100 1 100 1000 10 max4227/max4228 crosstalk vs. frequency -80 -90 MAX4223-12 frequency (mhz) crosstalk (db) -60 -70 -40 -50 -20 -30 r s = 50 w v out = 2vp-p ____________________________ t ypical operating characteristics (continued) (v cc = +5v, v ee = -5v, r l = 100 , t a = +25 c, unless otherwise noted.) 4 3 -6 1 100 1000 10 max4227/max4228 small-signal gain vs. frequency (a vcl = +2) -4 -5 MAX4223-09 frequency (mhz) normalized gain (db) -2 -3 0 -1 2 1 v in = 20mvp-p a vcl = +2v/v r f = r g = 470 w
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 6 _______________________________________________________________________________________ ____________________________ t ypical operating characteristics (continued) (v cc = +5v, v ee = -5v, r l = 100 , t a = +25 c, unless otherwise noted.) 10 0 -90 0.01 1 10 100 0.1 MAX4223/max4225/max4226 power-supply rejection ratio vs. frequency (a vcl = +1) -70 -80 MAX4223-13 frequency (mhz) psrr (db) -50 -60 -30 -40 -10 -20 a vcl = +1v/v r f = 560 w v cc v ee 10 0 -90 0.01 1 10 100 0.1 max4224/max4227/max4228 power-supply rejection ratio vs. frequency (a vcl = +2) -70 -80 MAX4223-14 frequency (mhz) psrr (db) -50 -60 -30 -40 -10 -20 a vcl = +2v/v r f = r g = 470 w v cc v ee 0.01 0.01 0.1 1 10 100 output impedance vs. frequency 0.1 MAX4223-15 frequency (mhz) output impedance ( w ) 1 10 100 max4224/7/8 a vcl = +2v/v r f = r g = 470 w MAX4223/5/6 a vcl = +1v/v r f = 560 w 20 -180 0.01 10 100 0.1 1 1000 shutdown mode output isolation vs. frequency -140 -160 MAX4223-16 frequency (mhz) shutdown mode output isolation (db) -100 -120 -60 -20 0 -40 -80 max4224/7/8 a vcl = +2v/v r f = r g = 470 w MAX4223/5/6 a vcl = +1v/v r f = 560 w -30 -90 0.1 10 100 max4224/max4227/max4228 total harmonic distortion vs. frequency (r l = 150 w ) -70 -50 -40 -60 -80 MAX4223-19 frequency (mhz) thd (dbc) 1 3rd harmonic 2nd harmonic thd -30 -90 0.1 10 100 MAX4223/max4225/max4226 total harmonic distortion vs. frequency (r l = 150 w ) -70 -50 -40 -60 -80 MAX4223-17 frequency (mhz) thd (dbc) 1 a vcl = +1v/v r l = 150 w r f = 560 w v out = 2vp-p 3rd harmonic 2nd harmonic thd -30 -100 0.1 10 100 MAX4223/max4225/max4226 total harmonic distortion vs. frequency (r l = 1k w ) -80 -60 -40 -70 -50 -90 MAX4223-18 frequency (mhz) thd (dbc) 1 a vcl = +1v/v r l = 1k w r f = 560 w v out = 2vp-p 2nd harmonic 3rd harmonic thd -30 -100 0.1 10 100 max4224/max4227/max4228 total harmonic distortion vs. frequency (r l = 1k w ) -80 -60 -40 -70 -50 -90 MAX4223-20 frequency (mhz) thd (dbc) 1 2nd harmonic 3rd harmonic thd 20 30 25 40 35 50 45 55 10 30 40 20 50 60 70 80 90 100 two-tone third-order intercept vs. frequency MAX4223-21 frequency (mhz) third-order intercept (dbm) max4224/7/8 MAX4223/5/6
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown _______________________________________________________________________________________ 7 ____________________________ t ypical operating characteristics (continued) (v cc = +5v, v ee = -5v, r l = 100 , t a = +25 c, unless otherwise noted.) +100mv -100mv input +100mv -100mv output gnd gnd time (10ns/div) MAX4223/max4225/max4226 small-signal pulse response (a vcl = +1) MAX4223-22 +100mv -100mv input +100mv -100mv output gnd gnd time (10ns/div) MAX4223/max4225/max4226 small-signal pulse response (a vcl = +1, c l = 25pf) MAX4223-23 +50mv -50mv input +100mv -100mv output gnd gnd time (10ns/div) max4224/max4227/max4228 small-signal pulse response (a vcl = +2) MAX4223-24 +50mv -50mv input +100mv -100mv output gnd gnd time (10ns/div) max4224/max4227/max4228 small-signal pulse response (a vcl = +2, c l = 10pf) MAX4223-25 +1v -1v input +2v -2v output gnd gnd time (10ns/div) max4224/max4227/max4228 large-signal pulse response (a vcl = +2) MAX4223-28 +2v -2v input +2v -2v output gnd gnd time (10ns/div) MAX4223/max4225/max4226 large-signal pulse response (a vcl = +1) MAX4223-26 +2v -2v input +2v -2v output gnd gnd time (10ns/div) MAX4223/max4225/max4226 large-signal pulse response (a vcl = +1, c l = 25pf) MAX4223-27 +1v -1v input +2v -2v output gnd gnd time (10ns/div) max4224/max4227/max4228 large-signal pulse response (a vcl = +2,c l = 10pf) MAX4223-29 +400mv -400mv input +2v -2v output gnd gnd time (10ns/div) max4224/max4227/max4228 large-signal pulse response (a vcl = +5) MAX4223-30
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 8 _______________________________________________________________________________________ 0 1 2 3 4 5 6 7 8 -50 0 -25 25 50 75 100 power-supply current per amplifier vs. temperature MAX4223-31 temperature (?) current (ma) normal mode shutdown mode 0 1 3 2 4 5 -50 0 -25 25 50 75 100 input bias current vs. temperature MAX4223-32 temperature (?) current ( m a) i b- i b+ 120 130 150 140 160 170 100 short-circuit output current vs. temperature MAX4223-33 temperature (?) current (ma) -50 0 -25 25 50 75 100 sourcing sinking 1.0 2.0 1.5 3.0 2.5 4.0 3.5 4.5 -50 0 25 -25 50 75 100 positive output swing vs. temperature MAX4223-34 temperature (?) positive output swing (v) r l = open r l = 50 w -4.5 -3.5 -4.0 -2.5 -3.0 -1.5 -2.0 -1.0 -50 0 25 -25 50 75 100 negative output swing vs. temperature MAX4223-35 temperature (?) negative output swing (v) r l = open r l = 50 w ____________________________ t ypical operating characteristics (continued) (v cc = +5v, v ee = -5v, r l = 100 , t a = +25 c, unless otherwise noted.)
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown _______________________________________________________________________________________ 9 function ______________________________________________________________ pin description 9 6 shdnb amplifier b shutdown input. connect to +5v for normal operation. connect to gnd for low-power shutdown mode. 13 6 7 9 5 outb amplifier b output shdna amplifier a shutdown input. connect to +5v for normal operation. connect to gnd for low-power shutdown mode. 11 12 5 7 6 8 inb+ amplifier b noninverting input inb- amplifier b inverting input 2 3 2 2 3 3 ina- amplifier a inverting input ina+ amplifier a noninverting input 4 2 6 7 14 1 8 10 1 1 v cc positive power-supply voltage. connect to +5v. outa amplifier a output in- amplifier inverting input shdn 5 8 amplifier shutdown. connect to +5v for normal operation. connect to gnd for low- power shutdown. 2 4 4 4 4 v ee negative power-supply voltage. connect to -5v. in+ 3 3 amplifier noninverting input out amplifier output 1 6 5, 7, 8, 10 n.c. no connect. not internally connected. tie to gnd for optimum ac performance. 1, 5 max4225 max4227 so max so so sot23 MAX4223/max4224 max4226/max4228 pin name function
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 10 ______________________________________________________________________________________ _______________ detailed description the MAX4223?ax4228 are ultra-high-speed, low- power, current-feedback amplifiers featuring -3db bandwidths up to 1ghz, 0.1db gain flatness up to 300mhz, and very low differential gain and phase errors of 0.01% and 0.02 , respectively. these devices operate on dual 5v or 3v power supplies and require only 6ma of supply current per amplifier. the MAX4223/max4225/max4226 are optimized for closed-loop gains of +1 (0db) or more and have -3db bandwidths of 1ghz. the max4224/max4227/ max4228 are optimized for closed-loop gains of +2 (6db) or more, and have -3db bandwidths of 600mhz (1.2ghz gain-bandwidth product). the current-mode feedback topology of these ampli - fiers allows them to achieve slew rates of up to 1700v/ s with corresponding large signal bandwidths up to 330mhz. each device in this family has an output that is capable of driving a minimum of 60ma of output current to 2.5v. theory of operation since the MAX4223?ax4228 are current-feedback amplifiers, their open-loop transfer function is expressed as a transimpedance: the frequency behavior of this open-loop transimped - ance is similar to the open-loop gain of a voltage-feed - back amplifier. that is, it has a large dc value and decreases at approximately 6db per octave. analyzing the current-feedback amplifier in a gain con - figuration (figure 1) yields the following transfer func - tion: at low gains, (g x r in- ) << r f . therefore, unlike tradi - tional voltage-feedback amplifiers, the closed-loop bandwidth is essentially independent of the closed- loop gain. note also that at low frequencies, t z >> [(g x r in- ) + r f ], so that: low-power shutdown mode the MAX4223/max4224/max4226/max4228 have a shutdown mode that is activated by driving the shdn input low. when powered from 5v supplies, the shdn input is compatible with ttl logic. placing the amplifier in shutdown mode reduces quiescent supply current to 350 a typical, and puts the amplifier output into a high- impedance state (100k typical). this feature allows these devices to be used as multiplexers in wideband systems. to implement the mux function, the outputs of multiple amplifiers can be tied together, and only the amplifier with the selected input will be enabled. all of the other amplifiers will be placed in the low-power shutdown mode, with their high output impedance pre - senting very little load to the active amplifier output. for gains of +2 or greater, the feedback network imped - ance of all the amplifiers used in a mux application must be considered when calculating the total load on the active amplifier output. __________ applications infor mation layout and power-supply bypassing the MAX4223?ax4228 have an extremely high band - width, and consequently require careful board layout, including the possible use of constant-impedance microstrip or stripline techniques. v v g r r out in f g = = + 1 . v v g x t s t s g x r r where g a r r out in z z in f v f g = ( ) ( ) + + = = + - 1 d d v i or t out in z - MAX4223 max4224 max4225 max4226 max4227 max4228 r g in- t z r in- out +1 in+ v in r f +1 figure 1. current-feedback amplifier
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown ______________________________________________________________________________________ 11 to realize the full ac performance of these high-speed amplifiers, pay careful attention to power-supply bypassing and board layout. the pc board should have at least two layers: a signal and power layer on one side and a large, low-impedance ground plane on the other. the ground plane should be as free of voids as possible, with one exception: the inverting input pin (in-) should have as low a capacitance to ground as possible. this means that there should be no ground plane under in- or under the components (r f and r g ) connected to it. with multilayer boards, locate the ground plane on a layer that incorporates no signal or power traces. whether or not a constant-impedance board is used, it is best to observe the following guidelines when designing the board: 1) do not use wire-wrapped boards (they are too inductive) or breadboards (they are too capacitive). 2) do not use ic sockets. ic sockets increase reac - tance. 3) keep signal lines as short and straight as possible. do not make 90 turns; round all corners. 4) observe high-frequency bypassing techniques to maintain the amplifier? accuracy and stability. 5) in general, surface-mount components have shorter bodies and lower parasitic reactance, giving better high-frequency performance than through-hole com - ponents. the bypass capacitors should include a 10nf ceramic, surface-mount capacitor between each supply pin and the ground plane, located as close to the package as possible. optionally, place a 10 f tantalum capacitor at the power-supply pins?point of entry to the pc board to ensure the integrity of incoming supplies. the power- supply trace should lead directly from the tantalum capacitor to the v cc and v ee pins. to minimize para - sitic inductance, keep pc traces short and use surface- mount components. the n.c. pins should be connected to a common ground plane on the pc board to minimize parasitic coupling. if input termination resistors and output back-termina - tion resistors are used, they should be surface-mount types, and should be placed as close to the ic pins as possible. tie all n.c. pins to the ground plane to mini - mize parasitic coupling. choosing feedback and gain resistors as with all current-feedback amplifiers, the frequency response of these devices depends critically on the value of the feedback resistor r f . r f combines with an internal compensation capacitor to form the dominant pole in the feedback loop. reducing r f ? value increases the pole frequency and the -3db bandwidth, but also increases peaking due to interaction with other nondominant poles. increasing r f ? value reduces peaking and bandwidth. table 1 shows optimal values for the feedback resistor (r f ) and gain-setting resistor (r g ) for the MAX4223 max4228. note that the max4224/max4227/max4228 offer superior ac performance for all gains except unity gain (0db). these values provide optimal ac response using surface-mount resistors and good layout tech - niques. maxim? high-speed amplifier evaluation kits provide practical examples of such layout techniques. stray capacitance at in- causes feedback resistor decoupling and produces peaking in the frequency- response curve. keep the capacitance at in- as low as possible by using surface-mount resistors and by avoiding the use of a ground plane beneath or beside these resistors and the in- pin. some capacitance is unavoidable; if necessary, its effects can be counter - acted by adjusting r f . use 1% resistors to maintain consistency over a wide range of production lots. table 1. optimal feedback resistor networks MAX4223/max4225/max4226 2 6 200 200 380 115 gain (db) r g ( ) r f ( ) 0.1db bw (mhz) gain (v/v) -3db bw (mhz) 5 14 100 25 235 65 2 6 470 470 600 200 5 14 240 62 400 90 10 20 130 15 195 35 max4224/max4227/max4228 * for the MAX4223eut, this optimal value is 470 . 1 0 560* open 1000 300
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 12 ______________________________________________________________________________________ dc and noise errors the MAX4223?ax4228 output offset voltage, v out (figure 2), can be calculated with the following equation: where: v os = input offset voltage (in volts) 1 + r f / r g = amplifier closed-loop gain (dimensionless) i b+ = input bias current (in amps) i b- = inverting input bias current (in amps) r g = gain-setting resistor (in ) r f = feedback resistor (in ) r s = source resistor (in ) the following equation represents output noise density: where: i n = input noise current density (in pa/ hz ) e n = input noise voltage density (in nv/ hz ) the MAX4223?ax4228 have a very low, 2nv/ hz noise voltage. the current noise at the noninverting input (i n+ ) is 3pa/ hz , and the current noise at the inverting input (i n- ) is 20pa/ hz . an example of dc-error calculations, using the max4224 typical data and the typical operating circuit with r f = r g = 470 (r f || r g = 235 ) and r s = 50 , gives: v out = [5 x 10 -4 x (1 + 1)] + [2 x 10 -6 x 50 x (1 + 1)] + [4 x 10 -6 x 470] v out = 3.1mv calculating total output noise in a similar manner yields the following: with a 600mhz system bandwidth, this calculates to 250 v rms (approximately 1.5mvp-p, using the six- sigma calculation). communication systems nonlinearities of components used in a communication system produce distortion of the desired output signal. intermodulation distortion (imd) is the distortion that results from the mixing of two input signals of different frequencies in a nonlinear system. in addition to the input signal frequencies, the resulting output signal contains new frequency components that represent the sum and difference products of the two input frequen - cies. if the two input signals are relatively close in fre - quency, the third-order sum and difference products will fall close to the frequency of the desired output and will therefore be very difficult to filter. the third-order intercept (ip3) is defined as the power level at which the amplitude of the largest third-order product is equal to the power level of the desired output signal. higher third-order intercept points correspond to better lineari - ty of the amplifier. the MAX4223?ax4228 have a typi - cal ip3 value of 42dbm, making them excellent choices for use in communications systems. adc input buffers input buffer amplifiers can be a source of significant errors in high-speed adc applications. the input buffer is usually required to rapidly charge and discharge the adc? input, which is often capacitive (see the section driving capacitive loads ). in addition, a high-speed adc? input impedance often changes very rapidly during the conversion cycle, requiring an amplifier with e x x x x x x e nv hz n out n out ( ) - - - ( ) = + ( ) ? ? ? ? ? + ? ? ? ? ? + ? ? ? = . / 1 1 3 10 50 20 10 235 2 10 10 2 12 12 2 9 2 2 e r r x i x r i x r r e n out f g n s n f g n ( ) + - = + ? ? ? ? ( ) + ( ) [ ] + ( ) || 1 2 2 2 v v x 1 r /r i x r x 1 r r i x r out os f g b s f g b f = + ( ) + + ? ? ? ? + + - MAX4223 max4224 max4225 max4226 max4227 max4228 r g in- i b- i b+ in+ v out out r s r f figure 2. output offset voltage
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown ______________________________________________________________________________________ 13 very low output impedance at high frequencies to main - tain measurement accuracy. the combination of high speed, fast slew rate, low noise, and low distortion makes the MAX4223?ax4228 ideally suited for use as buffer amplifiers in high-speed adc applications. video line driver the MAX4223?ax4228 are optimized to drive coaxial transmission lines when the cable is terminated at both ends, as shown in figure 3. note that cable frequency response may cause variations in the signal? flatness. driving capacitive loads a correctly terminated transmission line is purely resis - tive and presents no capacitive load to the amplifier. although the MAX4223?ax4228 are optimized for ac performance and are not designed to drive highly capacitive loads, they are capable of driving up to 25pf without excessive ringing. reactive loads decrease phase margin and may produce excessive ringing and oscillation (see typical operating characteristics ). figure 4? circuit reduces the effect of large capacitive loads. the small (usually 5 to 20 ) isolation resistor r iso , placed before the reactive load, prevents ringing and oscillation at the expense of a small gain error. at higher capacitive loads, ac perfor - mance is limited by the interaction of load capacitance with the isolation resistor. maxim? high-speed evaluation board layout figures 7 and 8 show a suggested layout for maxim? high-speed, single-amplifier evaluation boards. these boards were developed using the techniques described above. the smallest available surface-mount resistors were used for the feedback and back-termination resis - tors to minimize the distance from the ic to these resis - tors, thus reducing the capacitance associated with longer lead lengths. sma connectors were used for best high-frequency performance. because distances are extremely short, performance is unaffected by the fact that inputs and outputs do not match a 50 line. however, in applica - tions that require lead lengths greater than 1/4 of the wavelength of the highest frequency of interest, con - stant-impedance traces should be used. fully assembled evaluation boards are available for the MAX4223 in an so-8 package. MAX4223 max4224 max4225 max4226 max4227 max4228 r g in- in+ out r t 75 w r t 75 w r t 75 w 75 w cable 75 w cable r f figure 3. video line driver MAX4223 max4224 max4225 max4226 max4227 max4228 r g in- in+ r iso out r f c l r l figure 4. using an isolation resistor (r iso ) for high capacitive loads
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 14 ______________________________________________________________________________________ ac testing/performance ac specifications on high-speed amplifiers are usually guaranteed without 100% production testing. since these high-speed devices are sensitive to external par - asitics introduced when automatic handling equipment is used, it is impractical to guarantee ac parameters through volume production testing. these parasitics are greatly reduced when using the recommended pc board layout (like the maxim evaluation kit). characterizing the part in this way more accurately rep - resents the amplifier? true ac performance. some manufacturers guarantee ac specifications without clearly stating how this guarantee is made. the MAX4223?ax4228 ac specifications are derived from worst-case design simulations combined with a sample characterization of 100 units. the ac perfor - mance distributions along with the worst-case simula - tion limits are shown in figures 5 and 6. these distributions are repeatable provided that proper board layout and power-supply bypassing are used (see layout and power-supply bypassing section). 0 10 30 20 40 50 0?00 650?00 750?00 850?00 950?000 1050?100 1150?200 1250?300 1350?400 1450?500 MAX4223-fig5a -3db bandwidth (mhz) number of units 100 units simulation lower limit figure 5a. MAX4223 -3db bandwidth distribution 0 10 30 20 40 50 0?0 80?00 120?40 160?80 200?20 240?60 280?00 320?40 360?80 400?20 MAX4223-fig5b ?.1db bandwidth (mhz) number of units 100 units simulation lower limit figure 5b. MAX4223 0.1db bandwidth distribution 0 10 30 20 40 50 0?00 825?50 875?00 925?50 975?000 1025?050 1075?100 1125?150 1175?200 1225?250 MAX4223-fig5c rising-edge slew rate (v/ m s) number of units 100 units simulation lower limit figure 5c. MAX4223 rising-edge slew-rate distribution 0 10 30 20 40 50 0?00 525?50 575?00 625?50 675?00 725?50 775?00 825?50 875?00 925?50 MAX4223-fig5d falling-edge slew rate (v/ m s) number of units 100 units simulation lower limit figure 5d. MAX4223 falling-edge slew-rate distribution
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown ______________________________________________________________________________________ 15 0 10 30 20 40 50 0?00 250?00 350?00 450?00 550?00 650?00 750?00 850?00 950?000 1050?100 MAX4223-fig6a -3db bandwidth (mhz) number of units 100 units simulation lower limit figure 6a. max4224 -3db bandwidth distribution 0 10 30 20 40 50 0?0 60?0 100?20 140?60 180?00 220?40 260?80 300?20 340?60 380?00 MAX4223-fig6b ?.1db bandwidth (mhz) number of units 100 units simulation lower limit figure 6b. max4224 0.1db bandwidth distribution 0 10 30 20 40 50 0?400 1425?450 1475?500 1525?550 1575?600 1625?650 1675?700 1725?750 1775?800 1825?850 MAX4223-fig6c rising-edge slew rate (v/ m s) number of units 100 units simulation lower limit figure 6c. max4224 rising-edge slew-rate distribution 0 10 30 20 40 50 0?100 1125?150 1175?200 1225?250 1275?300 1325?350 1375?400 1425?450 1475?500 1525?550 MAX4223-fig6d falling-edge slew rate (v/ m s) number of units 100 units simulation lower limit figure 6d. max4224 falling-edge slew-rate distribution
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 16 ______________________________________________________________________________________ figure 7a. maxim sot23 high-speed evaluation board component placement guide?omponent side figure 7c. maxim sot23 high-speed evaluation board pc board layout?ack side figure 7b. maxim sot23 high-speed evaluation board pc board layout?omponent side
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown ______________________________________________________________________________________ 17 figure 8a. maxim so-8 high-speed evaluation board component placement guide?omponent side figure 8c. maxim so-8 high-speed evaluation board pc board layout?ack side figure 8b. maxim so-8 high-speed evaluation board pc board layout?omponent side
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown 18 ______________________________________________________________________________________ _____________________________________________ pin configurations (continued) out n.c. v ee 1 2 8 7 shdn v cc in- in+ n.c. so top view 3 4 6 5 MAX4223 max4224 max4226 max4228 max4226 max4228 inb- inb+ v ee 1 2 8 7 v cc outb ina- ina+ outa so 3 4 6 5 max4225 max4227 1 2 3 4 5 10 9 8 7 6 v cc outb inb- inb+ v ee ina+ ina- outa m max shdnb shdna 14 13 12 11 10 9 8 1 2 3 4 5 6 7 v cc outb inb- inb+ v ee ina+ ina- outa n.c. shdnb n.c. n.c. shdna n.c. so
MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown ______________________________________________________________________________________ 19 MAX4223/max4224 transistor count: 87 max4225?ax4228 transistor count: 171 substrate connected to v ee part max4224 eut-t max4224esa sot top mark aaae -40 c to +85 c -40 c to +85 c temp. range pin- package 6 sot23 8 so _ or dering infor mation (continued) ___________________ chip infor mation max4225 esa max4226 eub -40 c to +85 c -40 c to +85 c 8 so 10 max max4226esd -40 c to +85 c 14 so max4227 esa -40 c to +85 c 8 so max4228 eub max4228esd -40 c to +85 c -40 c to +85 c 10 max 14 so
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 20 __________________ maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 (408) 737-7600 1997 maxim integrated products printed usa is a registered trademark of maxim integrated products. MAX4223?ax4228 1ghz, low-power , sot23, cur r ent-feedback amplifiers with shutdown ________________________________________________________ package infor mation 10lumaxb.eps 6lsot.eps

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