View LTC6421CUDC-20-PBF_4345222.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

FEATURES
n n n n n n n n n n n n n n
LTC6421-20 Dual Matched 1.3GHz Differential Amplifiers/ADC Drivers DESCRIPTION
The LTC(R)6421-20 is a dual high speed differential amplifier targeted at processing signals from DC to 140MHz. The part has been specifically designed to drive 12-, 14- and 16-bit ADCs with low noise and low distortion, but can also be used as a general-purpose broadband gain block. The LTC6421-20 is easy to use, with minimal support circuitry required. The output common mode voltage is set using an external pin, independent of the inputs, which eliminates the need for transformers or AC-coupling capacitors in many applications. The gain is internally fixed at 20dB (10V/ V). The LTC6421-20 saves space and power compared to alternative solutions using IF gain blocks and transformers. The LTC6421-20 is packaged in a compact 20-lead 3mm x 4mm QFN package and operates over the - 40C to 85C temperature range.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Matched Gain 0.1dB Matched Phase 0.2 at 100MHz Channel Separation 80dB at 100MHz 1.3GHz -3dB Bandwidth; Fixed Gain of 10V/V (20dB) IMD3 = -76dBc at 100MHz, 2VP-P Equivalent OIP3 = 42dBm at 100MHz 1nV/Hz Internal Op Amp Noise 6.2dB Noise Figure Differential Inputs and Outputs Rail-to-Rail Output Swing 40mA Supply Current (120mW) per Amplifier 1V to 1.6V Output Common Mode Voltage, Adjustable DC- or AC-Coupled Operation 20-Lead 3mm x 4mm x 0.75mm QFN Package
APPLICATIONS
n n n n
Differential ADC Driver Differential Driver/Receiver Single Ended to Differential Conversion IF Sampling (Diversity) Receivers
TYPICAL APPLICATION
Matched Dual Amplifiers with Output Common Mode Biasing
3V 1000pF 0.1F VOCMA V+ A ZIN = 200 0.1F LTC6421-20 1000 -INA 100 12.5 +OUTA VOCMA PERCENTAGE OF UNITS 35 30 25 20 15 10 5 0.1F - INB 100 1000 V+ B 1000pF 0.1F VOCMB VOCMB ENABLEB
642120 TA01a
VOCMA
ENABLEA 40
Distribution of Gain Match
VINA
0.1F
+INA 100 V
-
12.5 - OUTA 1000 V-
VOCMA 0.1dB GAIN MATCHING 0.1 PHASE MATCHING AT 100MHz VOCMB
0.1F
1000 +INB 100 12.5 - OUTB
VINB
12.5 +OUTB
VOCMB
0 - 0.25 - 0.15 - 0.05 0.05 0.25 0.15 CHANNEL-TO-CHANNEL GAIN MATCH (dB)
642120 TA01b
ZIN = 200
3V
642120fa
1
LTC6421-20 ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW ENABLEA +OUTA 16 -OUTA 15 V + A 21 14 V - 13 V - 12 V + B 11 -OUTB 7 V+ B 8 VOCMB 9 10 ENABLEB +OUTB VOCMA
Supply Voltage (V + - V -) .........................................3.6V Input Current (Note 2)..........................................10mA Operating Temperature Range (Note 3)....-40C to 85C Specified Temperature Range (Note 4) ....-40C to 85C Storage Temperature Range...................-65C to 150C Maximum Junction Temperature........................... 150C Output Short-Circuit Duration .......................... Indefinite
+INA 1 -INA 2 V- 3 V- 4 -INB 5 +INB 6
UDC PACKAGE 20-LEAD (3mm x 4mm) PLASTIC QFN TJMAX = 150C, JA = 43C/W, JC = 5C/W EXPOSED PAD (PIN 21) IS V-, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH LTC6421CUDC-20#PBF LTC6421IUDC-20#PBF TAPE AND REEL LTC6421IUDC-20#TRPBF PART MARKING* LDDN PACKAGE DESCRIPTION 20-Lead (3mm x 4mm) Plastic QFN 20-Lead (3mm x 4mm) Plastic QFN SPECIFIED TEMPERATURE RANGE 0C to 70C -40C to 85C LTC6421CUDC-20#TRPBF LDDN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
SELECTOR GUIDE
PART NUMBER SINGLE LTC6400-8 LTC6400-14 LTC6400-20 LTC6400-26 LTC6401-8 LTC6401-14 LTC6401-20 LTC6401-26 LTC6421-20 LTC6420-20 DUAL GAIN (dB) 8 14 20 26 8 14 20 26 GAIN (V/V) 2.5 5 10 20 2.5 5 10 20 Z IN (DIFFERENTIAL) () 400 200 200 50 400 200 200 50 COMMENT Lowest Distortion Lowest Distortion Lowest Distortion Lowest Distortion Lowest Power Lowest Power Lowest Power Lowest Power
V+ A
20 19 18 17
642120fa
2
LTC6421-20 DC ELECTRICAL CHARACTERISTICS + The l -denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25C. V = 3V, V = 0V, +IN = -IN = VOCM = 1.25V, ENABLE = 0V, No RL unless otherwise noted.
PARAMETER Gain Gain Matching Gain Temperature Drift Output Swing Low (VOCM = 1.5V) Output Swing High (VOCM = 1.5V) Maximum Differential Output Swing Output Current Drive Input Offset Voltage Input Offset Voltage Drift Input Common Mode Voltage Range, MIN Input Common Mode Voltage Range, MAX Input Resistance (+IN, -IN) Input Impedance Matching Input Capacitance (+IN, -IN) Output Resistance (+OUT, -OUT) Common Mode Rejection Ratio Common Mode Gain Output Common Mode Range, MIN Output Common Mode Range, MAX Common Mode Offset Voltage Common Mode Offset Voltage Drift VOCM Input Current ENABLEx Input Low Voltage ENABLEx Input High Voltage ENABLEx Input Current Power Supply VS IS ISHDN PSRR Operating Supply Range Supply Current Shutdown Supply Current Power Supply Rejection Ratio (Differential Outputs) ENABLEx 0.8V; per Amplifier ENABLEx 2.4V; per Amplifier, Inputs Floating V + = 2.85V to 3.5V
l l l l
SYMBOL GDIFF G TCGAIN VSWINGMIN VSWINGMAX VOUTDIFFMAX IOUT VOS TCVOS IVRMIN IVRMAX RINDIFF RIN CINDIFF ROUTDIFF CMRR GCM VOCMMIN VOCMMAX VOSCM TCVOSCM IVOCM VIL VIH
CONDITIONS VIN = 100mV Differential Channel-to-Channel VIN = 100mV Differential Each Output, VIN = 400mV Differential Each Output, VIN = 400mV Differential 2VP-P, OUT (Note 10) Differential Differential
l l l l l l l l l l l
MIN 19.6
TYP 20 0.1 0.0015 0.1
MAX 20.4 0.25 0.25
UNITS dB dB dB/C V V VP-P mA
Input/Output Characteristic
2.75 5 10 -2
2.9 5.6 0.4 1.4 1 2
mV V/C V V % pF dB V/V
1.6 170 200 1 1 20 45 25 68 1 230 2.5 36
Differential Channel-to-Channel Differential, Includes Parasitic Differential Input Common Mode Voltage 1V to 1.6V VOCM = 1V to 1.6V
l l l l
Output Common Mode Voltage Control
l l
1 1.6 -10 -15 2 6 -3 0 0.8 2.4 1.5 2.85 3 40 1 55 86 0.5 3 3.5 50 3 10
V V mV V/C A V V A A V mA mA dB
VOCM = 1.25V to 1.5V
l l l l l l l
ENABLEx Pins (x = A, B)
ENABLEx 0.8V ENABLEx 2.4V
642120fa
3
LTC6421-20 AC ELECTRICAL CHARACTERISTICS
SYMBOL G P -3dBBW 0.5dBBW 0.1dBBW NF eIN eON 1/f SR tS1% tOVDR P1dB tON tOFF -3dBBWVOCM IMD3 OIP3 IIP3 HD2 HD3 PARAMETER Gain Matching Phase Matching Channel Separation (Note 8) -3dB Bandwidth Bandwidth for 0.5dB Flatness Bandwidth for 0.1dB Flatness Noise Figure Input Referred Voltage Noise Density 1/f Noise Corner Slew Rate 1% Settling Time Overdrive Recovery Time 1dB Compression Point Turn-On Time Turn-Off Time VOCM Pin Small Signal -3dB BW 3rd Order Intermodulation Distortion 3rd Order Output Intercept 3rd Order Input Intercept 2nd Order Harmonic Distortion 3rd Order Harmonic Distortion Differential (Note 6) 2VP-P, OUT (Note 6) 1.9VP-P, OUT (Note 6) Single Ended RL = 375 (Notes 5, 7), f = 100MHz +OUT, -OUT Within 10% of Final Values ICC Falls to 10% of Nominal 0.1VP-P at VOCM , Measured Single-Ended at Output (Note 6) f = 100MHz (1MHz Spacing), VOUT = 2VP-P Composite f = 100MHz (Note 7) f = 100MHz (ZIN = 50) f = 100MHz (ZIN = 200) f = 100MHz, VOUT = 2VP-P f = 100MHz, VOUT = 2VP-P
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. V+ = 3V, V- = 0V, VOCM = 1.25V, ENABLE = 0V, No RL unless otherwise noted.
CONDITIONS f = 100MHz (Note 9) f = 100MHz f = 100MHz 200mVP-P, OUT (Note 6) 200mVP-P, OUT (Note 6) 200mVP-P, OUT (Note 6) RL = 375 (Note 5), f = 100MHz Includes Resistors (Short Inputs), f = 100MHz
l
MIN
TYP 0.1 0.2 80 1.3 250 130 6.2 2.2 22 12.5 4500 2 7 18 80 150 15 -76 42 22 16 -74 -78
MAX 0.25
UNITS dB deg dB GHz MHz MHz dB nV/Hz nV/Hz kHz V/s ns ns dBm ns ns MHz dBc dBc dBc dBc dBc dBc
Output Referred Voltage Noise Density Includes Resistors (Short Inputs), f = 100MHz
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Input pins (+IN, -IN) are protected by steering diodes to either supply. If the inputs go beyond either supply rail, the input current should be limited to less than 10mA. Note 3: The LTC6421C and LTC6421I are guaranteed functional over the operating temperature range of -40C to 85C. Note 4: The LTC6421C is guaranteed to meet specified performance from 0C to 70C. It is designed, characterized and expected to meet specified performance from -40C to 85C but is not tested or QA sampled at these temperatures. The LTC6421I is guaranteed to meet specified performance from -40C to 85C. Note 5: Input and output baluns used. See Test Circuit A.
Note 6: Measured using Test Circuit B. RL = 87.5 on each output. Note 7: Since the LTC6421-20 is a feedback amplifier with low output impedance, a resistive load is not required when driving an AD converter. Therefore, typical output power is very small. In order to compare the LTC6421-20 with amplifiers that require 50 output load, the output voltage swing driving a given RL is converted to OIP3 and P1dB as if it were driving a 50 load. Using this modified convention, 2VP-P is by definition equal to 10dBm, regardless of actual RL. Note 8: Channel separation (the inverse of crosstalk) is measured by driving a signal into one input, while terminating the other input. Channel separation is the ratio of the resulting output signal at the driven channel to the channel that is not driven. Note 9: Not production tested. Guaranteed by design and by correlation to production tested parameters. Note 10: The output swing range is at least 2VP-P differential even when sourcing or sinking 20mA. Tested at VOCM = 1.5V.
642120fa
4
LTC6421-20 TYPICAL PERFORMANCE CHARACTERISTICS
Channel-to-Channel Gain Match vs Frequency
0.5 0.4 GROUP DELAY MATCH (ns) 0.3 GAIN MATCH (dB) 0.2 0.1 0 -0.1 - 0.2 - 0.3 - 0.4 - 0.5 10 100 FREQUENCY (MHz) 1000 2000
642120 G01
Channel-to-Channel Group Delay Match vs Frequency
0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 10 100 FREQUENCY (MHz) 1000 2000
642120 G02
Channel-to-Channel Phase Match vs Frequency
1.0
PHASE MATCH (DEG)
0.5
0
-0.5
-1.0 10 100 FREQUENCY (MHz) 500
642120 G03
Frequency Response
25 TEST CIRCUIT B 100
S21 Phase and Group Delay vs Frequency
TEST CIRCUIT B 1.5 0 -10
Input and Output Reflection and Reverse Isolation vs Frequency
TEST CIRCUIT B
20 PHASE (DEGREE)
0 PHASE -100 GROUP DELAY -200
1.2 S PARAMETERS (dB) GROUP DELAY (ns)
-20 -30 -40 -50 -60
S11
GAIN (dB)
15
0.9
S22
10
0.6
S12
5
-300
0.3 -70
0 10 100 1000 FREQUENCY (MHz) 3000
642120 G04
-400
0
200
400 600 FREQUENCY (MHz)
800
0 1000
642120 G05
-80 10 100 1000 FREQUENCY (MHz) 3000
642120 G06
Input and Output Impedance vs Frequency
250 225 IMPEDANCE MAGNITUDE () 200 175 150 125 100 75 50 25 0 1 PHASE IMPEDANCE MAGNITUDE ZOUT ZIN ZIN 100 80 60 40 20 0 -20 -40 -60 -80 -100 1000
642120 G07
Noise Figure and Input Referred Noise Voltage vs Frequency
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 10 6 1.35 INPUT REFERRED NOISE VOLTAGE (nV/Hz)
Small-Signal Transient Response
RL = 87.5 PER OUTPUT
IMPEDANCE PHASE (DEGREE)
OUTPUT VOLTAGE (V)
1.30
NOISE FIGURE (dB)
4 NOISE FIGURE
+OUT
1.25
eIN
2
1.20
-OUT
ZOUT 10 100 FREQUENCY (MHz)
100 FREQUENCY (MHz)
0 1000
642120 G08
1.15
0
5
10 TIME (ns)
15
20
642120 G09
642120fa
5
LTC6421-20 TYPICAL PERFORMANCE CHARACTERISTICS
Overdrive Transient Response
2.5 - OUT 2.0 OUTPUT VOLTAGE (V) RL = 87.5 PER OUTPUT HARMONIC DISTROTION (dBc) -40
Harmonic Distortion vs Frequency
DIFFERENTIAL INPUT VOUT = 2VP-P -50 DRIVING LTC2285 THIRD ORDER IMD (dBc) -40 -50 -60 -70 -80 -90 -100 -110 0 50 100 150 FREQUENCY (MHz) 200
642120 G11
Third Order Intermodulation Distortion vs Frequency
DIFFERENTIAL INPUT VOUT = 2VP-P COMPOSITE DRIVING LTC2235
-60 -70 -80 -90
1.5
HD2 HD3
1.0
0.5 +OUT 0
-100 0 50 100 TIME (ns) 150 200
642120 G10
-120 0 50 100 150 FREQUENCY (MHz) 200
642120 G12
Equivalent Output Third Order Intercept vs Frequency
70 60 OUTPUT IP3 (dBm) 50 40 30 20 10 0 DIFFERENTIAL INPUT VOUT = 2VP-P COMPOSITE (NOTE 7) DRIVING LTC2285 120
Channel Separation vs Frequency
(NOTE 8) CHANNEL SEPARATION (dB) 100 80 60 40 20 40
0
50
100 150 FREQUENCY (MHz)
200
642120 G13
1
10 100 FREQUENCY (MHz)
1000
642120 G14
642120fa
6
LTC6421-20 PIN FUNCTIONS
+INA, -INA, -INB, +INB (Pins 1, 2, 5, 6): Differential Inputs of A and B channel respectively. V - (Pins 3, 4, 13, 14, 21): Negative Power Supply. All four pins, as well as the exposed back, must be connected to same voltage/ground. ENABLEA, ENABLEB (Pins 9, 18): Logic inputs. If low, the amplifier is enabled. If high, the amplifier is disabled and placed in a low-power shutdown mode, making the amplifier outputs high impedance. These pins are internally separate. These pins should not be left floating. V + A , V + B (Pins 15, 20, 7, 12 ): Positive Power Supply (Normally tied to 3V or 3.3V). Supply pins of A and B channels are internally separate. Bypass each pin with 1000pF and 0.1F capacitors as close to the pins as possible. -OUTA, +OUTA, -OUTB, +OUTB (Pins 16, 17, 11, 10): Differential Outputs of channels A and B respectively. VOCMA , VOCMB (Pins 19, 8): These pins set the output common mode voltage for the respective channel. They are internally separate. A 0.1F external bypass capacitor is recommended. Exposed Pad (Pin 21): V -. The Exposed Pad must be connected to same voltage/ground as pins 3, 4, 13, 14.
642120fa
7
LTC6421-20 BLOCK DIAGRAM
V+ A 20 VOCMA 19 RF 1000 ENABLEA 18 +OUTA 17
RG 100 +INA 1 RG 100 -INA 2 V- 3 V- 4 -INB 5 +INB 6 RG 100
-+ +-
RF 1000
ROUT 12.5 16 -OUTA ROUT 12.5 15 V + A
14 V - 13 V - ROUT 12.5 ROUT 12.5
+ 12 V B
RG 100
RF 1000
+- -+
RF 1000
11 -OUTB
7 V+ B
8 VOCMB
9 ENABLEB
10 +OUTB
642120 BD
642120fa
8
LTC6421-20 APPLICATIONS INFORMATION
Circuit Operation Each of the two channels of the LTC6421-20 is composed of a fully differential amplifier with on chip feedback and output common mode voltage control circuitry. Differential gain and input impedance are set by 100/1000 resistors in the feedback network. Small output resistors of 12.5 improve the circuit stability over various load conditions. The LTC6421-20 is very flexible in terms of I/O coupling. It can be AC- or DC-coupled at the inputs, the outputs or both. If the inputs are AC-coupled, the input common mode voltage is automatically biased close to VOCM and thus no external circuitry is needed for bias. The LTC6421-20 provides an output common mode voltage set by VOCM , which allows driving an ADC directly without external components such as a transformer or AC coupling capacitors. The input signal can be either single-ended or differential with only minor differences in distortion performance. Input Impedance and Matching The differential input impedance of the LTC6421-20 is 200. If a 200 source impedance is unavailable, then the differential inputs may need to be terminated to a lower value impedance, e.g. 50, in order to provide an impedance match for the source. Several choices are available. One approach is to use a differential shunt resistor (Figure 1). Another approach is to employ a wide band transformer (Figure 2). Both methods provide a wide band impedance match. The termination resistor or the transformer must be placed close to the input pins in order to minimize the reflection due to input mismatch. Alternatively, one could apply a narrowband impedance match at the inputs of the LTC6421-20 for frequency selection and/or noise reduction.
25
1/2 LTC6421-20 100 +IN IN +
1000
25
1/2 LTC6421-20 100 +IN
1000
OUT -
+ -
66.5 IN - 25 -IN
642120 F01
+ -
OUT + 1000
VIN
TCM4-19
VIN
**
1:4
IN +
OUT -
IN - 25 -IN 100
OUT + 1000
100
642120 F02
Figure 1. Input Termination for Differential 50 Input Impedance Using Shunt Resistor
Figure 2. Input Termination for Differential 50 Input Impedance Using a 1:4 Balun
642120fa
9
LTC6421-20 APPLICATIONS INFORMATION
Referring to Figure 3, LTC6421-20 can be easily configured for single-ended input and differential output without a balun. The signal is fed to one of the inputs through a matching network while the other input is connected to the same matching network and a source resistor. Because the return ratios of the two feedback paths are equal, the two outputs have the same gain and thus symmetrical swing. In general, the single-ended input impedance and termination resistor RT are determined by the combination of RS, RG and RF. For example, when RS is 50, it is found that the single-ended input impedance is 202 and RT is 66.5 in order to match to a 50 source impedance. The LTC6421-20 is unconditionally stable. However, the overall differential gain is affected by both source impedance and load impedance as follows: AV = VOUT RL 2000 = * VIN RS + 200 25 + RL Output Impedance Match The LTC6421-20 can drive an ADC directly without external output impedance matching. Alternatively, the differential output impedance of 25 can be matched to a higher value impedance, e.g. 50, by series resistors or an LC network. Output Common Mode Adjustment The output common mode voltage is set by the VOCM pin, which is a high impedance input. The output common mode voltage is capable of tracking VOCM in a range from 1V to 1.6V. The bandwidth of VOCM control is typically 15MHz, which is dominated by a low pass filter connected to the VOCM pin and is aimed to reduce common mode noise generation at the outputs. The internal common mode feedback loop has a -3dB bandwidth of 300MHz, allowing fast rejection of any common mode output voltage disturbance. The VOCM pin should be tied to a DC bias
RS 50
0.1F
LTC6421-20 100 +IN IN +
1000
+ -
VIN RT 66.5
OUT -
IN - RS //RT 0.1F 28.7 100 -IN
OUT + 1000
642120 F03
Figure 3. Input Termination for Single-Ended 50 Input Impedance
642120fa
10
LTC6421-20 APPLICATIONS INFORMATION
voltage with a 0.1F bypass capacitor. When interfacing with A/D converters such as the LTC22xx families, the VOCM pin can be connected to the VCM pin of the ADC. Driving A/D Converters The LTC6421-20 has been specifically designed to interface directly with high speed A/D converters. The back page of this data sheet shows the LTC6421-20 driving an LTC2285, which is a dual 14-bit, 125Msps ADC. The VOCM pins of the LTC6421-20 are connected to the VCM pins of the LTC2285, which provide a DC voltage level of 1.5V. Both ICs are powered from the same 3V supply voltage. The inputs to the LTC6421-20 can be configured in various ways, as described in the Input Impedance and Matching section of this datasheet. The outputs of the LTC6421-20 may be connected directly to the analog inputs of an ADC, or a simple lowpass or bandpass filter network may be inserted to reduce out-of-band noise. Test Circuits Due to the fully-differential design of the LTC6421 and its usefulness in applications with differing characteristic specifications, two test circuits are used to generate the information in this datasheet. Test Circuit A is DC1299, a two-port demonstration circuit for the LTC6420/LTC6421 family. The schematic and silkscreen are shown in Figure 4. This circuit includes input and output transformers (baluns) for single-ended-to-differential conversion and impedance transformation, allowing direct hook-up to a 2-port network analyzer. There are also series resistors at the output to avoid loading the amplifier directly with a 50 load. Due to the input and output transformers, the -3dB bandwidth is reduced from 1.3GHz to approximately 1.1GHz. Test Circuit B uses a 4-port network analyzer to measure S-parameters and gain/phase response. This removes the effects of the wideband baluns and associated circuitry, for a true picture of the >1GHz S-parameters and AC characteristics.
642120fa
11
LTC6421-20 APPLICATIONS INFORMATION
Figure 4a. Top Silkscreen of DC1299 (Test Circuit A)
642120fa
12
LTC6421-20 APPLICATIONS INFORMATION
V+ R1 1.21k 1% R2 1k 1% J1 +INA C22 0.1F 1 2 5 C21 [1] T1 1 2 J2 -INA C22 [1] 1 2 4 R5 C25 [2] 0.1F R7 OPT R9 [2] 1 2 -INA 3 C31 [1] 1 2 5 C30 0.1F T2 1 2 J7 +INB C30 0.1F 1 2 4 R10 C34 [2] 0.1F R11 OPT R12 [2] V+ C18 0.1F 4 5 6 V- V- -INB +INB LTC6421-20 V+ A V- V- V+ B -OUTB V+ C18 0.1F C19 0.1F C16 V + ENA 0.1F JP1 1 DIS 2 3 EN R3 1.5k 1% TD4 VOCMA TD5 GND
R4 88.7 R5 R5 88.7 [1] V+ C35 1000pF 1
C17 [1] 3 2 1 TCM4-19+ C43 0.1F 2 C39 0.1F 3 T4 C32 0.1F 4 C28 0.1F 5 T2 4
C30 0.1F J3 1 2
+OUTA
**
[2] C22 0.1F
20 19 18 17 U1 V + A VOCMA ENABLEA +OUTA [2] +INA -OUTA 16 15 14 13 12 11
3
C34 [1] 1 2
J4 -OUTA
J5 -INB
C32 1000pF R12 R14 88.7 [1] R15 88.7
C35 [1] J6 1 2
-OUTB
**
[2] C22 [1]
3
V+ R16 1.21k 1%
V + B VOCMB ENABLEB +OUTB 21 7 8 9 10 R17 V + ENB JP2 1.5k 1 1% DIS 2 3 C19 EN 0.1F C42 0.1F
2 1 TCM4-19+ C44 0.1F C41 [1] 5 C40 0.1F J8 1 2
+OUTB
TD1 VOCMB TD2 V+ 2.85V TO 3.5V TD3 GND V+ C14 4.7F C15 1F
R18 1k 1%
NOTES: UNLESS OTHERWISE SPECIFIED [1] DO NOT STUFF [2] VERSION U1 R5, R9, R10, R13 -A -B LTC6420CUDC-20 LTC6421CUDC-20 NONE NONE
T1, T3 TCM4-19+ TCM4-19+
642020 F04b
Figure 4b. Demo Circuit 1299 Schematic (Test Circuit A)
642120fa
13
LTC6421-20 TYPICAL APPLICATIONS
Test Circuit B, 4-Port Measurements (Only the Signal-Path Connections Are Shown)
0.1F PORT 1 (50 ) 1/2 AGILENT E5071C PORT 2 (50 ) 200 0.1F RF 1000 0.1F +INA RG 100 - - -INA RG 100 + - RF 1000 + ROUT 12.5 -OUTA 37.4 PORT 4 (50 ) ROUT 12.5 +OUTA 37.4 0.1F PORT 3 (50 ) 1/2 AGILENT E5071C
642120 F04b
(B CHANNEL NOT SHOWN)
Parallel ADC Drivers to Reduce Wideband Noise
3.3V C1 0.1F R5 49.9 1/2 LTC6421-20 R6 49.9 C2 R3 12pF 10 C5 R4 12pF 10 C3 12pF LTC2208 VCM
642120 TA02
3.3V C4 0.1F
+ -
VIN
R7 49.9 1/2 LTC6421-20 VOCM R8 49.9
-3dB FILTER BANDWIDTH = 120MHz C6 2.2F
642120fa
14
LTC6421-20 PACKAGE DESCRIPTION
UDC Package 20-Lead Plastic QFN (3mm x 4mm)
(Reference LTC DWG # 05-08-1742 Rev O)
0.70 0.05 3.50 0.05 2.10 0.05 1.50 REF
2.65 0.05 1.65 0.05
PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.50 REF 3.10 0.05 4.50 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.75 0.05 3.00 0.10 R = 0.05 TYP 1.50 REF 19
PIN 1 NOTCH R = 0.20 OR 0.25 45 CHAMFER 20 0.40 0.10
PIN 1 TOP MARK (NOTE 6) 2.65 0.10 4.00 0.10 2.50 REF 1.65 0.10
1 2
(UDC20) QFN 1106 REV O
0.200 REF 0.00 - 0.05
R = 0.115 TYP
0.25 0.05 0.50 BSC
BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
642120fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC6421-20 TYPICAL APPLICATION
Dual ADC Driver for Wideband Direct-Conversion Receivers
3V C1 0.1F R1 40.2 R3 10 C2 12pF C3 12pF -3dB FILTER BANDWIDTH = 140MHz R4 10 1/2 LTC2285 VCM 3V C4 0.1F
+ -
1/2 VIN LTC6421-20
R2 40.2
642120 TA03
RELATED PARTS
PART NUMBER LT(R)1993-2 LT1993-4 LT1993-10 LT1994 LT5514 LT5524 LTC6400-14/ LTC6400-20/ LTC6400-26 LTC6401-8/ LTC6401-14/ LTC6401-20/ LTC6401-26 LT6402-6 LT6402-12 LT6402-20 LTC6404-1 LTC6404-2 LTC6404-4 LTC6406 LT6411 DESCRIPTION 800MHz Differential Amplifier/ADC Driver 900MHz Differential Amplifier/ADC Driver 700MHz Differential Amplifier/ADC Driver Low Noise, Low Distortion Differential Op Amp Ultralow Distortion IF Amplifier/ADC Driver with Digitally Controlled Gain Low Distortion IF Amplifier/ADC Driver with Digitally Controlled Gain Low Noise, Low Distortion, Differential ADC Drivers COMMENTS AV = 2V/V, OIP3 = 38dBm at 70MHz AV = 4V/V, OIP3 = 40dBm at 70MHz AV = 10V/V, OIP3 = 40dBm at 70MHz 16-Bit SNR and SFDR at 1MHz, Rail-to-Rail Outputs OIP3 = 47dBm at 100MHz, Gain Control Range 10.5dB to 33dB OIP3 = 40dBm at 100MHz, Gain Control Range 4.5dB to 37dB AV = 14dB/20dB/26dB, Single Amplifier per IC, High Performance High-Speed Differential Amplifiers/Differential Op Amps
Low Noise, Low Distortion, Differential ADC Drivers
AV = 8dB/14dB/20dB/26dB, Single Amplifier per IC, Low Power
300MHz Differential Amplifier/ADC Driver 300MHz Differential Amplifier/ADC Driver 300MHz Differential Amplifier/ADC Driver 600MHz, Low Noise, AC Precision, Fully Differential Input/Output Amplifier/Driver 900MHz, Low Noise, AC Precision, Fully Differential Input/Output Amplifier/Driver 1800MHz, Low Noise, AC Precision, Fully Differential Input/Output Amplifier/Driver 3GHz Rail-to-Rail Input Differential Op Amp Low Power Differential ADC Driver/Dual Selectable Gain Amplifier
AV = 6dB, Distortion < -80dBc at 25MHz AV = 12dB, Distortion < -80dBc at 25MHz AV = 20dB, Distortion < -80dBc at 25MHz AV = Unity Gain, en = 1.5nV/Hz, Distortion < -90dBc at 10MHz AV = 2V/V, en = 1.5nV/Hz, Distortion < -95dBc at 10MHz AV = 4V/V, en = 1.5nV/Hz, Distortion < -98dBc at 10MHz 1.6nV/Hz Noise, -72dBc Distortion at 50MHz, 18mA 16mA Supply Current, IMD3 = -83dBc at 70MHz, AV = 1, -1 or 2
642120fa
16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 1008 REV A * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2008

▲Up To Search▲

Price & Availability of LTC6421CUDC-20-PBF

	To Download LTC6421CUDC-20-PBF Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .