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LT1395/LT1396/LT1397 Single/Dual/Quad 400MHz Current Feedback Amplifier
FEATURES
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DESCRIPTIO
400MHz Bandwidth on 5V (AV = 1) 350MHz Bandwidth on 5V (AV = 2, -1) 0.1dB Gain Flatness: 100MHz (AV = 1, 2 and -1) High Slew Rate: 800V/s Wide Supply Range: 2V(4V) to 6V(12V) 80mA Output Current Low Supply Current: 4.6mA/Amplifier LT1395: SO-8 Package LT1396: SO-8 and MSOP Packages LT1397: SO-14 and SSOP-16 Packages
The LT (R)1395/LT1396/LT1397 are single/dual/quad 400MHz current feedback amplifiers with an 800V/s slew rate and the ability to drive up to 80mA of output current. The LT1395/LT1396/LT1397 operate on all supplies from a single 4V to 6V. At 5V, they draw 4.6mA of supply current per amplifier. The LT1395/LT1396/LT1397 are manufactured on Linear Technology's proprietary complementary bipolar process. They have standard single/dual/quad pinouts and they are optimized for use on supply voltages of 5V.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s s s s
Cable Drivers Video Amplifiers MUX Amplifiers High Speed Portable Equipment IF Amplifiers
TYPICAL APPLICATIO
R G1 1.02k R F1 255
Unity-Gain Video Loop-Through Amplifier
R G2 63.4 R F2 255
10 0
-
3.01k VIN - 1/2 LT1396
-
3.01k VIN+ 1/2 LT1396
-10
GAIN (dB)
VOUT
-20 -30 -40 COMMON MODE SIGNAL -50 -60 100
+
0.67pF
+
1% RESISTORS FOR A GAIN OF G: VOUT = G (VIN+ - VIN -) R F1 = RF2 R G1 = (G + 3) RF2 R RG2 = F2 G+3 TRIM CMRR WITH RG1
1395/6/7 TA01
0.67pF
12.1k
12.1k
BNC INPUTS HIGH INPUT RESISTANCE DOES NOT LOAD CABLE EVEN WHEN POWER IS OFF
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Loop-Through Amplifier Frequency Response
NORMAL SIGNAL 1k 10k 100k 1M 10M 100M 1G
1395/6/7 TA02
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FREQUENCY (Hz)
1
LT1395/LT1396/LT1397 ABSOLUTE AXI U RATI GS
Total Supply Voltage (V + to V -) ........................... 12.6V Input Current (Note 2) ....................................... 10mA Output Current ................................................. 100mA Differential Input Voltage (Note 2) ........................... 5V Output Short-Circuit Duration (Note 3) ........ Continuous
PACKAGE/ORDER I FOR ATIO
TOP VIEW NC 1 -IN 2 +IN 3 V- 4 - + 8 7 6 5 NC V+ OUT NC
OUT A -IN A +IN A V-
1 2 3 4
MS8 PACKAGE 8-LEAD PLASTIC MSOP
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 150C, JA = 150C/W
TJMAX = 150C, JA = 250C/W
ORDER PART NUMBER LT1395CS8 S8 PART MARKING 1395
TOP VIEW OUT A 1 -IN A 2 +IN A 3 V+ 4 + - - + 14 OUT D - 13 -IN D + 12 +IN D 11 V-
ORDER PART NUMBER LT1396CMS8 MS8 PART MARKING LTDY
+IN B 5 -IN B 6 OUT B 7
+ 10 +IN C - 9 -IN C 8 OUT C
S PACKAGE 14-LEAD PLASTIC SO
TJMAX = 150C, JA = 100C/W
ORDER PART NUMBER LT1397CS
Consult factory for Industrial and Military grade parts.
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(Note 1)
Operating Temperature Range (Note 4) . - 40C to 85C Specified Temperature Range (Note 5) .. - 40C to 85C Storage Temperature Range ................ - 65C to 150C Junction Temperature (Note 6) ............................ 150C Lead Temperature (Soldering, 10 sec)................. 300C
TOP VIEW
- +
TOP VIEW
- +
8 7 6 5
V+ OUT B -IN A +IN B
OUT A 1 -IN A 2 +IN A 3 V- 4 - +
8 7 - + 6 5
V+ OUT B -IN A +IN B
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 150C, JA = 150C/W
ORDER PART NUMBER LT1396CS8 S8 PART MARKING 1396
TOP VIEW OUT A -IN A +IN A V+ +IN B -IN B OUT B NC 1 2 3 4 5 6 7 8 + - - + 16 OUT D - 15 -IN D + 14 +IN D 13 V - + 12 +IN C - 11 -IN C 10 OUT C 9 NC
GN PACKAGE 16-LEAD PLASTIC SSOP
TJMAX = 150C, JA = 135C/W
ORDER PART NUMBER LT1397CGN GN PART MARKING 1397
LT1395/LT1396/LT1397
The q denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25C. For each amplifier: VCM = 0V, VS = 5V, pulse tested, unless otherwise noted. (Note 5)
SYMBOL VOS VOS/T IIN+ IIN- en + in - in RIN CIN VINH VINL VOUTH PARAMETER Input Offset Voltage
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
TYP 1
MAX 10 12 25 30 50 60
UNITS mV mV V/C A A A A nV/Hz pA/Hz pA/Hz M pF V V
Input Offset Voltage Drift Noninverting Input Current
q q
15 10 10
Inverting Input Current
q
Input Noise Voltage Density Noninverting Input Noise Current Density Inverting Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range, High Input Voltage Range, Low Output Voltage Swing, High
f = 1kHz, RF = 1k, RG = 10, RS = 0 f = 1kHz f = 1kHz VIN = 3.5V VS = 5V VS = 5V, 0V VS = 5V VS = 5V, 0V VS = 5V VS = 5V VS = 5V, 0V VS = 5V VS = 5V VS = 5V, 0V VS = 5V, RL = 150 VS = 5V, RL = 150 VS = 5V, 0V; RL = 150 VS = 5V, RL = 150 VS = 5V, RL = 150 VS = 5V, 0V; RL = 150 VCM = 3.5V VCM = 3.5V VCM = 3.5V VS = 2V to 5V VS = 2V to 5V
q q
4.5 6 25 0.3 3.5 1 2.0
q q
4.0 4.0 - 4.0 1.0 - 3.5
V V V V V
q
3.9 3.7
4.2 4.2 - 4.2
VOUTL
Output Voltage Swing, Low
q
- 3.9 - 3.7
0.8
q
V V V V V V
VOUTH
Output Voltage Swing, High
3.4 3.2
3.6 3.6 - 3.6
VOUTL
Output Voltage Swing, Low
q
- 3.4 - 3.2
0.6
q q q
V V V dB A/V A/V dB A/V A/V A/V dB k mA
CMRR - ICMRR PSRR + IPSRR - IPSRR AV ROL IOUT IS SR - 3dB BW 0.1dB BW
Common Mode Rejection Ratio Inverting Input Current Common Mode Rejection Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection Large-Signal Voltage Gain Transimpedance, VOUT/IIN- Maximum Output Current Supply Current per Amplifier Slew Rate (Note 7) -3dB Bandwidth 0.1dB Bandwidth
42
52 10 16 22 2 3 7
56
70 1
VS = 2V to 5V VOUT = 2V, RL = 150 VOUT = 2V, RL = 150 RL = 0 AV = - 1, RL = 150 AV = 1, RF = 374, RL = 100 AV = 2, RF = RG = 255, RL = 100 AV = 1, RF = 374, RL = 100 AV = 2, RF = RG = 255, RL = 100
q
2 50 40 65 100 4.6 500 800 400 300 100 100
q q
80 6.5
mA V/s MHz MHz MHz MHz
3
LT1395/LT1396/LT1397
The q denotes specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25C. For each amplifier: VCM = 0V, VS = 5V, pulse tested, unless otherwise noted. (Note 5)
SYMBOL tr, tf tPD os tS dG dP PARAMETER Small-Signal Rise and Fall Time Propagation Delay Small-Signal Overshoot Settling Time Differential Gain (Note 8) Differential Phase (Note 8) CONDITIONS RF = RG = 255, RL = 100, VOUT = 1VP-P RF = RG = 255, RL = 100, VOUT = 1VP-P RF = RG = 255, RL = 100, VOUT = 1VP-P 0.1%, AV = - 1, RF = RG = 280, RL = 150 RF = RG = 255, RL = 150 RF = RG = 255, RL = 150 MIN TYP 1.3 2.5 10 25 0.02 0.04 MAX UNITS ns ns % ns % DEG
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: This parameter is guaranteed to meet specified performance through design and characterization. It has not been tested. Note 3: A heat sink may be required depending on the power supply voltage and how many amplifiers have their outputs short circuited. Note 4: The LT1395C/LT1396C/LT1397C are guaranteed functional over the operating temperature range of - 40C to 85C. Note 5: The LT1395C/LT1396C/LT1397C are guaranteed to meet specified performance from 0C to 70C. The LT1395C/LT1396C/LT1397C are designed, characterized and expected to meet specified performance from - 40C and 85C but is not tested or QA sampled at these temperatures. For guaranteed I-grade parts, consult the factory.
Note 6: TJ is calculated from the ambient temperature TA and the power dissipation PD according to the following formula: LT1395CS8: TJ = TA + (PD * 150C/W) LT1396CS8: TJ = TA + (PD * 150C/W) LT1396CMS8: TJ = TA + (PD * 250C/W) LT1397CS14: TJ = TA + (PD * 100C/W) LT1397CGN16: TJ = TA + (PD * 135C/W) Note 7: Slew rate is measured at 2V on a 3V output signal. Note 8: Differential gain and phase are measured using a Tektronix TSG120YC/NTSC signal generator and a Tektronix 1780R Video Measurement Set. The resolution of this equipment is 0.1% and 0.1. Ten identical amplifier stages were cascaded giving an effective resolution of 0.01% and 0.01.
TYPICAL AC PERFOR A CE
VS (V) 5 5 5 AV 1 2 -1 RL () 100 100 100 RF () 374 255 280 RG () - 255 280 SMALL SIGNAL - 3dB BW (MHz) 400 350 350 SMALL SIGNAL 0.1dB BW (MHz) 100 100 100 SMALL SIGNAL PEAKING (dB) 0.1 0.1 0.1
TYPICAL PERFOR A CE CHARACTERISTICS
Closed-Loop Gain vs Frequency (AV = 1) Closed-Loop Gain vs Frequency (AV = 2) Closed-Loop Gain vs Frequency (AV = - 1)
0 GAIN (dB) GAIN (dB) -2 -4 -6
GAIN (dB) 1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = RG = 255 RL = 100 1G
1397 G02
1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = 374 RL = 100
1G
1397 G01
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UW
UW
6 4 2 0
0 -2 -4 -6
1M 10M 100M VS = 5V FREQUENCY (Hz) VIN = -10dBm RF = RG = 280 RL = 100
1G
1397 G03
LT1395/LT1396/LT1397
TYPICAL PERFOR A CE CHARACTERISTICS
Large-Signal Transient Response (AV = 1) Large-Signal Transient Response (AV = 2) Large-Signal Transient Response (AV = - 1)
OUTPUT (1V/DIV)
OUTPUT (1V/DIV)
VS = 5V VIN = 2.5V RF = 374 RL = 100
TIME (10ns/DIV)
1395/6/7 G04
VS = 5V TIME (10ns/DIV) VIN = 1.25V RF = RG = 255 RL = 100
1395/6/7 G05
OUTPUT (1V/DIV)
2nd and 3rd Harmonic Distortion vs Frequency
30
8 7
OUTPUT VOLTAGE (VP-P)
DISTORTION (dB)
TA = 25C 40 RF = RG = 255 RL = 100 50 VS = 5V VOUT = 2VPP 60 70 80 90 100 110 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M
1397 G07
5 4 3 2 1M 10M FREQUENCY (Hz) 100M
1397 G08
PSRR (dB)
HD3
HD2
Input Voltage Noise and Current Noise vs Frequency
1000 INPUT NOISE (nV/Hz OR pA/Hz) 100
OUTPUT IMPEDANCE ()
100
CAPACITIVE LOAD (pF)
-in 10 en +in
1 10 30 100 300 1k 3k 10k 30k 100k FREQUENCY (Hz)
1397 G10
UW
VS = 5V TIME (10ns/DIV) VIN = 2.5V RF = RG = 280 RL = 100
1395/6/7 G06
Maximum Undistorted Output Voltage vs Frequency
80 70
PSRR vs Frequency
AV = +1 6
AV = +2
60 50 40 30 20 10 TA = 25C RF = RG = 255 RL = 100 AV = +2 100k 1M 10M FREQUENCY (Hz) 100M
1397 G09
- PSRR
+ PSRR
TA = 25C RF = 374 (AV = 1) RF = RG = 255 (AV = 2) RL = 100 VS = 5V
0 10k
Output Impedance vs Frequency
1000 RF = RG = 255 RL = 50 AV = +2 VS = 5V
Maximum Capacitive Load vs Feedback Resistor
10
100
1
10 RF = RG AV = +2 VS = 5V PEAKING 5dB 900 1500 2100 2700 FEEDBACK RESISTANCE () 3300
1397 G13
0.1
0.01 10k
100k
1M 10M FREQUENCY (Hz)
100M
1397 G11
1 300
5
LT1395/LT1396/LT1397
TYPICAL PERFOR A CE CHARACTERISTICS
Capacitive Load vs Output Series Resistor
40
OUTPUT SERIES RESISTANCE ()
SUPPLY CURRENT (mA)
30
OUTPUT VOLTAGE SWING (V)
RF = RG = 255 VS = 5V OVERSHOOT < 2%
20
10
0 10 100 CAPACITIVE LOAD (pF) 1000
1397 G14
Positive Supply Current per Amplifier vs Temperature
POSITIVE SUPPLY CURRENT PER AMPLIFIER (mA)
5.00 4.95 4.90 4.85 4.80 4.75 4.70 4.65 4.60 4.55
VS = 5V
INPUT OFFSET VOLTAGE (mV)
2.0 1.5 1.0 0.5 0 - 0.5
INPUT BIAS CURRENT (A)
4.50 -50 -25
75 100 50 25 AMBIENT TEMPERATURE (C) 0
Square Wave Response
OUTPUT (200mV/DIV)
INPUT (100mV/DIV)
RL = 100 RF = RG = 255 f = 10MHz
TIME (10ns/DIV)
1395/6/7 G22
tPD = 2.5ns AV = +2 TIME (500ps/DIV) RL = 100 RF = RG = 255
VOUT (200mV/DIV)
6
UW
1397 G17
Supply Current vs Supply Voltage
6 5 4 3 2 1 0 0 1 2 7 3 5 6 4 SUPPLY VOLTAGE ( V) 8 9 5 4 3 2 1 0 -1 -2 -3 -4
Output Voltage Swing vs Temperature
RL = 100k
RL = 150
VS = 5V
RL = 100k
RL = 150
-5 50 25 0 75 100 -50 -25 AMBIENT TEMPERATURE (C)
125
1397 G15
1397 G16
Input Offset Voltage vs Temperature
3.0 2.5 12 VS = 5V 15
Input Bias Currents vs Temperature
VS = 5V
IB+ 9
IB -
6
3
125
-1.0 - 50 - 25
75 100 50 25 AMBIENT TEMPERATURE (C) 0
125
0 -50 -25
50 100 25 75 0 AMBIENT TEMPERATURE (C)
125
1397 G18
1397 G19
Propagation Delay
Rise Time and Overshoot
OS = 10%
OUTPUT (200mV/DIV)
1395/6/7 G20
tr = 1.3ns AV = +2 TIME (500ps/DIV) RL = 100 RF = RG = 255
1395/6/7 G21
LT1395/LT1396/LT1397
PIN FUNCTIONS
LT1395CS8 NC (Pin 1): No Connection. - IN (Pin 2): Inverting Input. + IN (Pin 3): Noninverting Input. V - (Pin 4): Negative Supply Voltage, Usually - 5V. NC (Pin 5): No Connection. OUT (Pin 6): Output. V + (Pin 7): Positive Supply Voltage, Usually 5V. NC (Pin 8): No Connection. LT1396CMS8, LT1396CS8 OUT A (Pin 1): A Channel Output. - IN A (Pin 2): Inverting Input of A Channel Amplifier. + IN A (Pin 3): Noninverting Input of A Channel Amplifier. V - (Pin 4): Negative Supply Voltage, Usually - 5V. + IN B (Pin 5): Noninverting Input of B Channel Amplifier. - IN B (Pin 6): Inverting Input of B Channel Amplifier. OUT B (Pin 7): B Channel Output. V + (Pin 8): Positive Supply Voltage, Usually 5V. LT1397CS OUT A (Pin 1): A Channel Output. - IN A (Pin 2): Inverting Input of A Channel Amplifier. + IN A (Pin 3): Noninverting Input of A Channel Amplifier. V + (Pin 4): Positive Supply Voltage, Usually 5V. + IN B (Pin 5): Noninverting Input of B Channel Amplifier. - IN B (Pin 6): Inverting Input of B Channel Amplifier. OUT B (Pin 7): B Channel Output. OUT C (Pin 8): C Channel Output. - IN C (Pin 9): Inverting Input of C Channel Amplifier. + IN C (Pin 10): Noninverting Input of C Channel Amplifier. V - (Pin 11): Negative Supply Voltage, Usually - 5V. + IN D (Pin 12): Noninverting Input of D Channel Amplifier. - IN D (Pin 13): Inverting Input of D Channel Amplifier. OUT D (Pin 14): D Channel Output. LT1397CGN OUT A (Pin 1): A Channel Output. - IN A (Pin 2): Inverting Input of A Channel Amplifier. + IN A (Pin 3): Noninverting Input of A Channel Amplifier. V + (Pin 4): Positive Supply Voltage, Usually 5V. + IN B (Pin 5): Noninverting Input of B Channel Amplifier. - IN B (Pin 6): Inverting Input of B Channel Amplifier. OUT B (Pin 7): B Channel Output. NC (Pin 8): No Connection. NC (Pin 9): No Connection. OUT C (Pin 10): C Channel Output. - IN C (Pin 11): Inverting Input of C Channel Amplifier. + IN C (Pin 12): Noninverting Input of C Channel Amplifier. V - (Pin 13): Negative Supply Voltage, Usually - 5V. + IN D (Pin 14): Noninverting Input of D Channel Amplifier. - IN D (Pin 15): Inverting Input of D Channel Amplifier. OUT D (Pin 16): D Channel Output.
APPLICATI
S I FOR ATIO
Feedback Resistor Selection The small-signal bandwidth of the LT1395/LT1396/LT1397 is set by the external feedback resistors and the internal junction capacitors. As a result, the bandwidth is a function of the supply voltage, the value of the feedback
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resistor, the closed-loop gain and the load resistor. The LT1395/LT1396/LT1397 have been optimized for 5V supply operation and have a - 3dB bandwidth of 400MHz at a gain of 1 and 350MHz at a gain of 2. Please refer to the resistor selection guide in the Typical AC Performance table.
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LT1395/LT1396/LT1397
APPLICATI
S I FOR ATIO
Capacitance on the Inverting Input Current feedback amplifiers require resistive feedback from the output to the inverting input for stable operation. Take care to minimize the stray capacitance between the output and the inverting input. Capacitance on the inverting input to ground will cause peaking in the frequency response (and overshoot in the transient response). Capacitive Loads The LT1395/LT1396/LT1397 can drive many capacitive loads directly when the proper value of feedback resistor is used. The required value for the feedback resistor will increase as load capacitance increases and as closed-loop gain decreases. Alternatively, a small resistor (5 to 35) can be put in series with the output to isolate the capacitive load from the amplifier output. This has the advantage that the amplifier bandwidth is only reduced when the capacitive load is present. The disadvantage is that the gain is a function of the load resistance. See the Typical Performance Characteristics curves. Power Supplies The LT1395/LT1396/LT1397 will operate from single or split supplies from 2V (4V total) to 6V (12V total). It is not necessary to use equal value split supplies, however the offset voltage and inverting input bias current will change. The offset voltage changes about 2.5mV per volt of supply mismatch. The inverting bias current will typically change about 10A per volt of supply mismatch. Slew Rate Unlike a traditional voltage feedback op amp, the slew rate of a current feedback amplifier is not independent of the amplifier gain configuration. In a current feedback amplifier, both the input stage and the output stage have slew rate limitations. In the inverting mode, and for gains of 2 or more in the noninverting mode, the signal amplitude between the input pins is small and the overall slew rate is that of the output stage. For gains less than 2 in the noninverting mode, the overall slew rate is limited by the input stage. The input slew rate of the LT1395/LT1396/LT1397 is approximately 600V/s and is set by internal currents and capacitances. The output slew rate is set by the value of
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the feedback resistor and internal capacitance. At a gain of 2 with 255 feedback and gain resistors and 5V supplies, the output slew rate is typically 800V/s. Larger feedback resistors will reduce the slew rate as will lower supply voltages. Differential Input Signal Swing To avoid any breakdown condition on the input transistors, the differential input swing must be limited to 5V. In normal operation, the differential voltage between the input pins is small, so the 5V limit is not an issue. Buffered RGB to Color-Difference Matrix An LT1397 can be used to create buffered color-difference signals from RGB inputs (Figure 1). In this application, the R input arrives via 75 coax. It is routed to the noninverting input of LT1397 amplifier A1 and to a 845 resistor R8. There is also an 82.5 termination resistor R11, which yields a 75 input impedance at the R input when considered in parallel with R8. R8 connects to the inverting input of a second LT1397 amplifier (A2), which also sums the weighted G and B inputs to create a -0.5 * Y output. LT1397 amplifier A3 then takes the -0.5 * Y output and amplifies it by a gain of -2, resulting in the Y output. Amplifier A1 is configured in a noninverting gain of 2 with the bottom of the gain resistor R2 tied to the Y output. The output of amplifier A1 thus results in the color-difference output R-Y. The B input is similar to the R input. It arrives via 75 coax, and is routed to the noninverting input of LT1397 amplifier A4, and to a 2320 resistor R10. There is also a 76.8 termination resistor R13, which yields a 75 input impedance when considered in parallel with R10. R10 also connects to the inverting input of amplifier A2, adding the B contribution to the Y signal as discussed above. Amplifier A4 is configured in a noninverting gain of 2 configuration with the bottom of the gain resistor R4 tied to the Y output. The output of amplifier A4 thus results in the color-difference output B-Y. The G input also arrives via 75 coax and adds its contribution to the Y signal via a 432 resistor R9, which is tied to the inverting input of amplifier A2. There is also a 90.9 termination resistor R12, which yields a 75
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LT1395/LT1396/LT1397
APPLICATI
S I FOR ATIO
termination when considered in parallel with R9. Using superposition, it is straightforward to determine the output of amplifier A2. Although inverted, it sums the R, G and B signals in the standard proportions of 0.3R, 0.59G and 0.11B that are used to create the Y signal. Amplifier A3 then inverts and amplifies the signal by 2, resulting in the Y output.
75 SOURCES R R11 82.5 G R12 90.9 B R13 76.8 R10 2320 R9 432 R7 255
+
R8 845 A1 1/4 LT1397 R-Y R1 255
-
A2 1/4 LT1397
R6 127
R5 255
A3 1/4 LT1397
ALL RESISTORS 1% VS = 5V
A4 1/4 LT1397
1395/6/7 F01
Figure 1. Buffered RGB to Color-Difference Matrix
Buffered Color-Difference to RGB Matrix An LT1395 combined with an LT1396 can be used to create buffered RGB outputs from color-difference signals (Figure 2). The R output is a back-terminated 75 signal created using resistor R5 and amplifier A1 configured for a gain of +2 via 255 resistors R3 and R4. The noninverting input of amplifier A1 is connected via 1k resistors R1 and R2 to the Y and R-Y inputs respectively, resulting in cancellation of the Y signal at the amplifier input. The remaining R signal is then amplified by A1. The B output is also a back-terminated 75 signal created using resistor R16 and amplifier A3 configured for a gain of +2 via 255 resistors R14 and R15. The noninverting input of amplifier A3 is connected via 1k resistors R12 and R13 to the Y and B-Y inputs respectively, resulting in cancellation of the Y signal at the amplifier input. The remaining B signal is then amplified by A3. The G output is the most complicated of the three. It is a weighted sum of the Y, R-Y and B-Y inputs. The Y input
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is attenuated via resistors R6 and R7 such that amplifier A2's noninverting input sees 0.83Y. Using superposition, we can calculate the positive gain of A2 by assuming that R8 and R9 are grounded. This results in a gain of 2.41 and a contribution at the output of A2 of 2Y. The R-Y input is amplified by A2 with the gain set by resistors R8 and R10, giving an amplification of -1.02. This results in a contribution at the output of A2 of 1.02Y - 1.02R. The B-Y input is amplified by A2 with the gain set by resistors R9 and R10, giving an amplification of - 0.37. This results in a contribution at the output of A2 of 0.37Y - 0.37B. If we now sum the three contributions at the output of A2, we get: A2OUT = 3.40Y - 1.02R - 0.37B It is important to remember though that Y is a weighted sum of R, G and B such that: Y = 0.3R + 0.59G + 0.11B
R3 255 B-Y R2 255 Y R4 255
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If we substitute for Y at the output of A2 we then get: A2OUT = (1.02R - 1.02R) + 2G + (0.37B - 0.37B) = 2G The back-termination resistor R11 then halves the output of A2 resulting in the G output.
R1 1k Y R2 1k R-Y
+
A1 1/2 LT1396
R5 75 R R3 267
-
R6 205 R7 1k R8 261 R9 698 B-Y R12 1k R13 1k ALL RESISTORS 1% VS = 5V
R4 267
+
A2 LT1395
R11 75 G R10 267
-
+
A3 1/2 LT1396
R16 75 B R14 267
-
R15 267
1395/6/7 F02
Figure 2. Buffered Color-Difference to RGB Matrix
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LT1395/LT1396/LT1397
SI PLIFIED SCHE ATIC , each amplifier
V+
PACKAGE DESCRIPTIO
0.007 - 0.0098 (0.178 - 0.249) 0.016 - 0.050 (0.406 - 1.270)
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
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+IN
-IN
OUT
V-
1395/6/7 SS
Dimensions in inches (millimeters) unless otherwise noted. GN Package 16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.189 - 0.196* (4.801 - 4.978) 16 15 14 13 12 11 10 9
0.009 (0.229) REF
0.229 - 0.244 (5.817 - 6.198)
0.150 - 0.157** (3.810 - 3.988)
1 0.015 0.004 x 45 (0.38 0.10) 0 - 8 TYP 0.053 - 0.068 (1.351 - 1.727)
23
4
56
7
8 0.004 - 0.0098 (0.102 - 0.249)
0.008 - 0.012 (0.203 - 0.305)
0.0250 (0.635) BSC
GN16 (SSOP) 1098
LT1395/LT1396/LT1397 PACKAGE DESCRIPTIO U
Dimensions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.102)
0.040 0.006 (1.02 0.15) 0.007 (0.18) 0.021 0.006 (0.53 0.015) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC
0.034 0.004 (0.86 0.102)
8
76
5
0.006 0.004 (0.15 0.102)
0.193 0.006 (4.90 0.15)
0.118 0.004** (3.00 0.102)
MSOP (MS8) 1098
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
1
23
4
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP 0.053 - 0.069 (1.346 - 1.752) 8 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157** (3.810 - 3.988) 7 6 5
0.014 - 0.019 (0.355 - 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) BSC
1
2
3
4
SO8 1298
S Package 14-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.337 - 0.344* (8.560 - 8.738) 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0.053 - 0.069 (1.346 - 1.752) 0 - 8 TYP 14 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157** (3.810 - 3.988) 13 12 11 10 9 8
0.014 - 0.019 (0.355 - 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) BSC
S14 1298
1
2
3
4
5
6
7
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.
11
LT1395/LT1396/LT1397
TYPICAL APPLICATI
Single Supply RGB Video Amplifier The LT1395 can be used with a single supply voltage of 6V or more to drive ground-referenced RGB video. In Figure 3, two 1N4148 diodes D1 and D2 have been placed in series with the output of the LT1395 amplifier A1 but within the feedback loop formed by resistor R8. These diodes effectively level-shift A1's output downward by 2 diodes, allowing the circuit output to swing to ground. Amplifier A1 is used in a positive gain configuration. The feedback resistor R8 is 255. The gain resistor is created from the parallel combination of R6 and R7, giving a Thevenin equivalent 63.5 connected to 3.75V. This gives an AC gain of + 5 from the noninverting input of amplifier A1 to the cathode of D2. However, the video input is also attenuated before arriving at A1's positive
VIN
RELATED PARTS
PART NUMBER LT1227/LT1229/LT1230 LT1252/LT1253/LT1254 LT1398/LT1399 LT1675 LT1363/LT1364/LT1365 DESCRIPTION 140MHz Single/Dual/Quad Current Feedback Amplifier Low Cost Video Amplifiers Dual/Triple Current Feedback Amplifiers Triple 2:1 Buffered Video Mulitplexer 70MHz Single/Dual/Quad Op Amps COMMENTS 1100V/s Slew Rate, Single Adds Shutdown Pin Single, Dual and Quad 100MHz Current Feedback Amplifiers 300MHz Bandwidth, 0.1dB Flatness > 150MHz with Shutdown 2.5ns Switching Time, 250MHz Bandwidth 1000V/s Slew Rate, Voltage Feedback
139567f LT/TP 0100 4K * PRINTED IN USA
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
UO
input. Assuming a 75 source impedance for the signal driving VIN, the Thevenin equivalent signal arriving at A1's positive input is 3V + 0.4VIN, with a source impedance of 714. The combination of these two inputs gives an output at the cathode of D2 of 2 * VIN with no additional DC offset. The 75 back termination resistor R9 halves the signal again such that VOUT equals a buffered version of VIN. It is important to note that the 4.7F capacitor C1 has been added to provide enough current to maintain the voltage drop across diodes D1 and D2 when the circuit output drops low enough that the diodes might otherwise turn off. This means that this circuit works fine for continuous video input, but will require that C1 charge up after a period of inactivity at the input.
5V VS 6V TO 12V C1 4.7F D2 D1 1N4148 1N4148 R1 1000 R2 1300 R3 160 R4 75 R5 2.32 R6 84.5
+
A1 LT1395
R9 75
VOUT
-
R8 255
1395/6/7 TA03
R7 255
Figure 3. Single Supply RGB Video Amplifier (1 of 4 Channels)
(c) LINEAR TECHNOLOGY CORPORATION 1999

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