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LT1227 140MHz Video Current Feedback Amplifier
FEATURES
s s s s s s s s s s s s
DESCRIPTIO
140MHz Bandwidth: AV = 2, RL = 150 1100V/s Slew Rate Low Cost 30mA Output Drive Current 0.01% Differential Gain 0.01 Differential Phase High Input Impedance: 14M, 3pF Wide Supply Range: 2V to 15V Shutdown Mode: IS < 250A Low Supply Current: IS = 10mA Inputs Common Mode to Within 1.5V of Supplies Outputs Swing Within 0.8V of Supplies
The LT(R)1227 is a current feedback amplifier with wide bandwidth and excellent video characteristics. The low differential gain and phase, wide bandwidth, and 30mA output drive current make the LT1227 well suited to drive cables in video systems. A shutdown feature switches the device into a high impedance, low current mode, allowing multiple devices to be connected in parallel and selected. Input to output isolation in shutdown is 70dB at 10MHz for input amplitudes up to 10VP-P. The shutdown pin interfaces to open collector or open drain logic and takes only 4s to enable or disable. The LT1227 comes in the industry standard pinout and can upgrade the performance of many older products. For a dual or quad version, see the LT1229/1230 data sheet. The LT1227 is manufactured on Linear Technology's proprietary complementary bipolar process.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Video Amplifiers Cable Drivers RGB Amplifiers Test Equipment Amplifiers 50 Buffers for Driving Mixers
TYPICAL APPLICATIO
Video Cable Driver
0.20
VIN
Differential Gain and Phase vs Supply Voltage
0.20 NTSC COMPOSITE f = 3.58MHz
+
LT1227
75
DIFFERENTIAL PHASE (DEG)
0.16
-
RF 1k
75 CABLE VOUT
0.12
0.08 0.04 G 0 5 7 11 13 9 SUPPLY VOLTAGE (V) 15
RG 1k
VOUT =1 VIN
75
1227 TA01
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0.16
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DIFFERENTIAL GAIN (%)
0.12
0.08
0.04
0
LT1227 * TA02
1
LT1227 ABSOLUTE
(Note 1)
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RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW NULL 1 -IN 2 +IN 3 V- 4 8 SHDN 7 V+ 6 OUT 5 NULL
Supply Voltage ..................................................... 18V Input Current ...................................................... 15mA Output Short Circuit Duration (Note 2) ........ Continuous Operating Temperature Range LT1227C .................................................. 0C to 70C LT1227M (OBSOLETE) .................... - 55C to 125C Storage Temperature Range ................. - 65C to 150C Junction Temperature Plastic Package ................................................ 150C Ceramic Package (OBSOLETE) ........................ 175C Lead Temperature (Soldering, 10 sec.)................ 300C
ORDER PART NUMBER LT1227CN8
N8 PACKAGE 8-LEAD PLASTIC DIP TJMAX = 150C, JA = 100C/W (N) J8 PACKAGE 8-LEAD CERAMIC DIP TJMAX = 175C, JA = 100C/W (J)
LT1227MJ8
OBSOLETE PACKAGE
Consider the N8 Package for Alternate Source. TOP VIEW NULL 1 -IN 2 +IN 3 V- 4 8 SHDN 7 V+ 6 OUT
ORDER PART NUMBER LT1227CS8 S8 PART MARKING 1227
5 NULL
S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 150C, JA = 150C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCM = 0, 5V VS 15V, pulse tested, unless otherwise noted.
SYMBOL VOS PARAMETER Input Offset Voltage Input Offset Voltage Drift Noninverting Input Current Inverting Input Current Input Noise Voltage Density Noninverting Input Noise Current Density Inverting Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range CONDITIONS TA = 25C
q q
ELECTRICAL CHARACTERISTICS
MIN
TYP 3 10 0.3 10
MAX 10 15 3 10 60 100
IIN+ IIN- en +in -in RIN CIN
TA = 25C
q
TA = 25C
q
f = 1kHz, RF = 1k, RG = 10, RS = 0 f = 1kHz f = 1kHz VIN = 13V, VS = 15V VIN = 3V, VS = 5V VS = 15V, TA = 25C
q q
1.5 1.5 13 12 3 2 55 55 55 55
3.2 1.7 32 14 11 3 13.5 3.5 62 61
q
VS = 5V, TA = 25C
q
CMRR
Common Mode Rejection Ratio
VS = 15V, VCM = 13V, TA = 25C VS = 15V, VCM = 12V VS = 5V, VCM = 3V, TA = 25C VS = 5V, VCM = 2V
q q
UNITS mV mV V/C A A A A nV/Hz pA/Hz pA/Hz M M pF V V V V dB dB dB dB
2
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LT1227
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER Inverting Input Current Common Mode Rejection
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCM = 0, 5V VS 15V, pulse tested, unless otherwise noted.
CONDITIONS VS = 15V, VCM = 13V, TA = 25C VS = 15V, VCM = 12V VS = 5V, VCM = 3V, TA = 25C VS = 5V, VCM = 2V VS = 2V to 15V, TA = 25C VS = 3V to 15V VS = 2V to 15V, TA = 25C VS = 3V to 15V VS = 2V to 15V, TA = 25C VS = 3V to 15V VS = 15V, VOUT = 10V, RL = 1k VS = 5V, VOUT = 2V, RL = 150 VS = 15V, VOUT = 10V, RL = 1k VS = 5V, VOUT = 2V, RL = 150 VS = 15V, RL = 400, TA = 25C VS = 5V, RL = 150, TA = 25C
q
MIN
q
TYP 3.5 4.5
q q q
MAX 10 10 10 10
PSRR
Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection Large-Signal Voltage Gain Transresistance, VOUT/IIN- Maximum Output Voltage Swing
60 60
80 2 0.25 50 50 5 5
q q q q q q
AV ROL VOUT
IOUT IS
Maximum Output Current Supply Current (Note 3) Positive Supply Current, Shutdown
RL = 0, TA = 25C VS = 15V, VOUT = 0V, TA = 25C
q
55 55 100 100 12 10 3 2.5 30
72 72 270 240 13.5 3.7 60 10 120
VS = 15V, Pin 8 Voltage = 0V, TA = 25C
q
I8 SR tr, tf BW tr, tf
tS
Shutdown Pin Current (Note 4) Output Leakage Current, Shutdown Slew Rate (Notes 5 and 6) Rise and Fall Time, VOUT = 1VP-P Small-Signal Bandwidth Small-Signal Rise and Fall Time Propagation Delay Small-Signal Overshoot Settling Time Differential Gain (Note 7) Differential Phase (Note 7)
VS = 15V VS = 15V, Pin 8 Voltage = 0V, TA = 25C TA = 25C VS = 5V, RF = 1k, RG = 1k, RL = 150 VS = 15V, RF = 1k, RG = 1k, RL = 150 VS = 15V, RF = 1k, RG = 1k, RL = 100 VS = 15V, RF = 1k, RG = 1k, RL = 100 VS = 15V, RF = 1k, RG = 1k, RL = 100 0.1%, VOUT = 10V, RF = 1k, RG = 1k, RL = 1k VS = 15V, RF = 1k, RG = 1k, RL = 150 VS = 15V, RF = 1k, RG = 1k, RL = 1k VS = 15V, RF = 1k, RG = 1k, RL = 150 VS = 15V, RF = 1k, RG = 1k, RL = 1k
q
15.0 17.5 300 500 300 10
500
1100 8.7 140 3.3 3.4 5 50 0.014 0.010 0.010 0.013
UNITS A/V A/V A/V A/V dB dB nA/V nA/V A/V A/V dB dB k k V V V V mA mA mA A A A A V/s ns MHz ns ns % ns % % DEG DEG
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: A heat sink may be required depending on the power supply voltage. Note 3: The supply current of the LT1227 has a negative temperature coefficient. For more information, see Typical Performance Characteristics curves.
Note 4: Ramp Pin 8 voltage down from 15V while measuring IS. When IS drops to less than 0.5mA, measure Pin 8 current. Note 5: Slew rate is measured at 5V on a 10V output signal while operating on 15V supplies with RF = 2k, RG = 220 and R L = 400. Note 6: AC parameters are 100% tested on the ceramic and plastic DIP package parts (J and N suffix) and are sample tested on every lot of the SO packaged parts (S suffix). Note 7: NTSC composite video with an output level of 2V.
3
LT1227
TYPICAL PERFOR A CE CHARACTERISTICS
Voltage Gain and Phase vs Frequency, Gain = 6dB
10 9 8 PHASE 0
-3dB BANDWIDTH (MHz)
VOLTAGE GAIN (dB)
7 6 5 4 3 2 1 0 0.1 VS = 15V RL = 100 RF = 910 1 10 FREQUENCY (MHz) 100
LT1227 * TPC01
135 GAIN 180 225
120 100 80 60 40 20 0
RF = 500 RF = 750 RF = 1k
-3dB BANDWIDTH (MHz)
Voltage Gain and Phase vs Frequency, Gain = 20dB
24 23 22
VOLTAGE GAIN (dB)
PHASE
21 20 19 18 17 16 15 14 0.1 VS = 15V RL = 100 RF = 825 1 10 FREQUENCY (MHz) 100
LT1227 * TPC04
135 GAIN 180 225
-3dB BANDWIDTH (MHz)
-3dB BANDWIDTH (MHz)
Voltage Gain and Phase vs Frequency, Gain = 40dB
44 43 42 PHASE 0
-3dB BANDWIDTH (MHz)
VOLTAGE GAIN (dB)
41 40 39 38 37 36 35 34 0.1 VS = 15V RL = 100 RF = 500 1 10 FREQUENCY (MHz) 100
LT1227 * TPC07
135 GAIN 180 225
12 10 8 6 4 2 0 0 2 4
RF = 500 RF = 1k RF = 2k
-3dB BANDWIDTH (MHz)
4
UW
-3dB Bandwidth vs Supply Voltage, Gain = 2, RL = 100
180 160 140 PEAKING 0.5dB PEAKING 5dB
PHASE SHIFT (DEG) PHASE SHIFT (DEG) PHASE SHIFT (DEG)
-3dB Bandwidth vs Supply Voltage, Gain = 2, RL = 1k
180 160 140 120 100 80 60 40 20 16 0 18 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V) 16 18 RF = 1.5k RF = 1k PEAKING 0.5dB PEAKING 5dB RF = 750 RF = 2k
45 90
RF = 2k 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V)
LT1227 * TPC02
LT1227 * TPC03
-3dB Bandwidth vs Supply Voltage, Gain = 10, RL = 100
0 45 90
180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V) 16 18 RF = 2k RF = 250 RF = 500 RF = 750 RF = 1k PEAKING 0.5dB PEAKING 5dB
-3dB Bandwidth vs Supply Voltage, Gain = 10, RL = 1k
180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V) 16 18 RF = 2k RF = 750 RF = 1k RF = 500 PEAKING 0.5dB PEAKING 5dB
LT1227 * TPC05
LT1227 * TPC06
-3dB Bandwidth vs Supply Voltage, Gain = 100, RL = 100
18 16 14
18 16 14 12 10 8 6 4 2 0
-3dB Bandwidth vs Supply Voltage, Gain = 100, RL = 1k
RF = 500 RF = 1k
45 90
RF = 2k
6 8 10 12 14 SUPPLY VOLTAGE (V)
16
18
0
2
4
6 8 10 12 14 SUPPLY VOLTAGE (V)
16
18
LT1227 * TPC08
LT1227 * TPC09
LT1227
TYPICAL PERFOR A CE CHARACTERISTICS
Maximum Capacitive Load vs Feedback Resistor
10000 TOTAL HARMONIC DISTORTION (%) RL = 1k PEAKING 5dB GAIN = 2 CAPACITIVE LOAD (pF) 1000
0.1 VS = 15V RL = 400 RF = RG = 1k OUTPUT VOLTAGE (VP-P)
VS = 5V
100
VS = 15V
10
1 0 2 1 FEEDBACK RESISTOR (k) 3
Input Common Mode Limit vs Temperature
V+ V+
OUTPUT SATURATION VOLTAGE (V)
-0.5
COMMON MODE RANGE (V)
-1.0 -1.5 -2.0
V + = 2V TO 18V
-0.5 -1.0
OUTPUT SHORT-CIRCUIT CURRENT (mA)
2.0 1.5 1.0 0.5 V- -50 -25 50 25 0 75 TEMPERATURE (C) 100 125 V - = -2V TO -18V
Spot Noise Voltage and Current vs Frequency
100
POWER SUPPLY REJECTION (dB)
SPOT NOISE (nV/Hz OR pA/Hz)
-in
POSITIVE NEGATIVE 40
OUTPUT IMPEDANCE ()
10
en +in 1 10 100 1k 10k FREQUENCY (Hz) 100k
LT1227 * TPC16
UW
LT1227 * TPC10
LT1227 * TPC13
Total Harmonic Distortion vs Frequency
25
Maximum Undistorted Output vs Frequency
VS = 15V RL = 1k RF = 1k AV = +10 AV = -1 AV = +1 AV = +2
20
15
0.01
VO = 7VRMS
10
VO = 1VRMS
5
0.001 10
0
100
1k 10k FREQUENCY (Hz)
100k
LT1227 * TPC11
1
10 FREQUENCY (MHz)
100
LT1127 * TPC12
Output Saturation Voltage vs Temperature
RL = 2V VS 18V 70
Output Short-Circuit Current vs Junction Temperature
60
50
1.0 0.5 V- -50 -25
40
50 25 75 0 TEMPERATURE (C)
100
125
30 -50 -25
0
25 50 75 100 125 150 175 TEMPERATURE (C)
LT1227 * TPC15
LT1227 * TPC14
Power Supply Rejection vs Frequency
80 VS = 15V RL = 100 RF = RG = 1k
Output Impedance vs Frequency
100 VS = 15V
60
10 RF = RG = 2k RF = RG = 1k 0.1
1
20
0.01
0 10k
100k
1M 10M FREQUENCY (Hz)
100M
LT1227 * TPC17
0.001 10k
100k
1M 10M FREQUENCY (Hz)
100M
LT1227 * TPC18
5
LT1227
TYPICAL PERFOR A CE CHARACTERISTICS
Settling Time to 10mV vs Output Step
10 8 6
OUTPUT STEP (V)
VS = 15V RF = RG = 1k
SUPPLY CURRENT (mA)
NONINVERTING INVERTING
OUTPUT STEP (V)
4 2 0 -2 -4 -6 -8 -10 0 20
60 40 SETTLING TIME (ns)
Output Impedance in Shutdown vs Frequency
100 VS = 15V AV = 1 RF = 1.5k 0 0.05 0.10 0.15 0.20 0.25 0.1 100k
DIFFERENTIAL PHASE (DEG)
OUTPUT IMPEDANCE (k)
DIFFERENTIAL GAIN (%)
10
1
1M 10M FREQUENCY (Hz)
2nd and 3rd Harmonic Distortion vs Frequency
-20 VS = 15V VO = 2VP-P RL = 100 RF = 820 AV = 10dB 2ND 3RD
-30
3RD ORDER INTERCEPT (dBm)
DISTORTION (dBc)
-40
-50
-60
-70 1 10 FREQUENCY (MHz) 100
LT1227 * TPC25
6
UW
80
LT1227 * TPC19
LT1227 * TPC22
Settling Time to 1mV vs Output Step
10 8 6 4 2 0 -2 -4 -6 -8 100 -10 0 4 12 16 8 SETTLING TIME (s) 20 NONINVERTING INVERTING
14
Supply Current vs Supply Voltage
13 12 11 10 9 8 7 6 5 4 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V) 16 18 125C 175C -55C
VS = 15V RF = RG = 1k
25C
LT1227 * TPC20
LT1227 * TPC21
Differential Phase vs Frequency
0 (VO)DC = 0.5V 1.0V 1.5V 2.0V 0.01 0.02 0.03 0.04 0.05
Differential Gain vs Frequency
(VO)DC = 0.5V 1.0V 2.0V VS = 15V AV = 2 RL = 1k RF = 1k RG = 1k 1M 10M 100M
LT1227 * TPC24
100M
0.30 100k
VS = 15V AV = 2 RL = 1k RF = 1k RG = 1k 1M 10M 100M
LT1227 * TPC23
0.06 100k
FREQUENCY (Hz)
FREQUENCY (Hz)
3rd Order Intercept vs Frequency
45 40 35 30 25 20 15 0 10 20 30 40 FREQUENCY (MHz) 50 60 VS = 15V RL = 100 RF = 680 RG = 75
Test Circuit for 3rd Order Intercept +
LT1227
50 PO
-
680
75 MEASURE INTERCEPT AT PO
50
1227 TC
LT1227 * TPC26
LT1227
SI PLIFIED SCHE ATIC
7 V+
14k
CURRENT SOURCE BIAS
8 S/D +IN 3 2 -IN 6 VOUT
APPLICATI
S I FOR ATIO
The LT1227 is a very fast current feedback amplifier. Because it is a current feedback amplifier, the bandwidth is maintained over a wide range of voltage gains. The amplifier is designed to drive low impedance loads such as cables with excellent linearity at high frequencies. Feedback Resistor Selection The small-signal bandwidth of the LT1227 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 resistor, the closed-loop gain and load resistor. The characteristic curves of Bandwidth vs Supply Voltage show the effect of a heavy load (100) and a light load (1k). These curves use a solid line when the response has less than 0.5dB of peaking and a dashed line when the response has 0.5dB to
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NULL 1
NULL 5
4 V-
1227 SS
5dB of peaking. The curves stop where the response has more than 5dB of peaking. At a gain of two, on 15V supplies with a 1k feedback resistor, the bandwidth into a light load is over 140MHz, but into a heavy load the bandwidth reduces to 120MHz. The loading has this effect because there is a mild resonance in the output stage that enhances the bandwidth at light loads but has its Q reduced by the heavy load. This enhancement is only useful at low gain settlings; at a gain of ten it does not boost the bandwidth. At unity gain, the enhancement is so effective the value of the feedback resistor has very little effect. At very high closed-loop gains, the bandwidth is limited by the gain bandwidth product of about 1GHz. The curves show that the bandwidth at a closed-loop gain of 100 is 12MHz, only one tenth what it is at a gain of two.
7
LT1227
APPLICATI S I FOR ATIO
Small-Signal Rise Time, AV = +2
VOUT
RF = 1k, RG= 1k, RL = 100
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), but it does not degrade the stability of the amplifier. Capacitive Loads The LT1227 can drive capacitive loads directly when the proper value of feedback resistor is used. The graph of Maximum Capacitive Load vs Feedback Resistor should be used to select the appropriate value. The value shown is for 5dB peaking when driving a 1k load at a gain of 2. This is a worst case condition, the amplifier is more stable at higher gains and driving heavier loads. Alternatively, a small resistor (10 to 20) 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 and the disadvantage that the gain is a function of the load resistance. Power Supplies The LT1227 will operate from single or split supplies from 2V (4V total) to 15V (30V total). It is not necessary to use equal value split supplies, however the offset voltage
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and inverting input bias current will change. The offset voltage changes about 500V per volt of supply mismatch. The inverting bias current can change as much as 5.0A per volt of supply mismatch, though typically the change is less than 0.5A per volt. Slew Rate The slew rate of a current feedback amplifier is not independent of the amplifier gain configuration the way slew rate is in a traditional op amp. This is because both the input stage and the output stage have slew rate limitations. In the inverting mode, and for higher gains 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 ten in the noninverting mode, the overall slew rate is limited by the input stage. The input stage slew rate of the LT1227 is approximately 125V/s and is set by internal currents and capacitances. The output slew rate is set by the value of the feedback resistors and the internal capacitances. At a gain of ten with a 1k feedback resistor and 15V supplies, the output slew rate is typically 1100V/s. Larger feedback resistors will reduce the slew rate as will lower supply voltages, similar to the way the bandwidth is reduced. The graph of Maximum Undistorted Output vs Frequency relates the slew rate limitations to sinusoidal inputs for various gain configurations.
Large-Signal Transient Response, AV = +10
AI01
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VOUT
RF = 910, RG= 100, RL = 400
AI02
LT1227
APPLICATI S I FOR ATIO
Large-Signal Transient Response, AV = +2
VOUT
RF = 1k, RG= 1k, RL = 400
Large-Signal Transient Response, AV = -2
VOUT
RF = 1k, RG= 510, RL = 400
Settling Time The characteristic curves show that the LT1227 amplifier settles to within 10mV of final value in 40ns to 55ns for any output step up to 10V. The curve of settling to 1mV of final value shows that there is a slower thermal contribution up to 20s. The thermal settling component comes from the output and the input stage. The output contributes just under 1mV per volt of output change and the input contributes 300V per volt of input change. Fortunately the input thermal tends to cancel the output thermal. For this reason the noninverting gain of two configuration settles faster than the inverting gain of one.
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Shutdown The LT1227 has a high impedance, low supply current mode which is controlled by Pin 8. In the shutdown mode, the output looks like a 12pF capacitor and the supply current drops to approximately the Pin 8 current. The shutdown pin is referenced to the positive supply through an internal pullup circuit (see the simplified schematic). Pulling a current of greater than 50A from Pin 8 will put the device into the shutdown mode. An easy way to force shutdown is to ground Pin 8, using open drain (collector) logic. Because the pin is referenced to the positive supply, the logic used should have a breakdown voltage of greater than the positive supply voltage. No other circuitry is necessary as an internal JFET limits the Pin 8 current to about 100A. When Pin 8 is open, the LT1227 operates normally. Differential Input Signal Swing The differential input swing is limited to about 6V by an ESD protection device connected between the inputs. In normal operation, the differential voltage between the input pins is small, so this clamp has no effect; however, in the shutdown mode, the differential swing can be the same as the input swing. The clamp voltage will then set the maximum allowable input voltage. To allow for some margin, it is recommended that the input signal be less than 5V when the device is shutdown. Offset Adjust Pins 1 and 5 are provided for offset nulling. A small current to V + or ground will compensate for DC offsets in the device. The pins are referenced to the positive supply (see the simplified schematic) and should be left open if unused. The offset adjust pins act primarily on the inverting input bias current. A 10k pot connected to Pins 1 and 5 with the wiper connected to V + will null out the bias current, but will not affect the offset voltage much. Since the output offset is VO AV * VOS + (IIN -) * RF at higher gains (AV > 5), the VOS term will dominate. To null out the VOS term, use a 10k pot between Pins 1 and 5 with a 150k resistor from the wiper to ground for 15V split supplies, 47k for 5V split supplies.
AI03 AI04 AI04
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LT1227
TYPICAL APPLICATI
MUX Amplifier
The shutdown function can be effectively used to construct a MUX amplifier. A two-channel version is shown, but more inputs could be added with suitable logic. By configuring each amplifier as a unity-gain follower, there is no loading by the feedback network when the amplifier is off. The open drains of the 74C906 buffers are used to interface the 5V logic to the shutdown pin. Feedthrough from the unselected input to the output is -70dB at 10MHz. The differential voltage between MUX inputs VIN1 and VIN2 appears across the inputs of the shutdown device, this voltage should be less than 5V to avoid turning on the clamp diodes discussed previously. If the inputs are sinusoidal having a zero DC level, this implies that the amplitude of each input should be less than 5VP-P. The output impedance of the off amplifier remains high until the output level exceeds approximately 6VP-P at 10MHz, this sets the maximum usable output level. Switching time between inputs is about 4s without an external pullup. Adding a 10k pullup resistor from each shutdown pin to V + will reduce the switching time to 2s but will increase the positive supply current in shutdown by 1.5mA.
MUX Output MUX Input Crosstalk vs Frequency
-40
VOUT
INPUT CROSSTALK (dB)
INPUT SELECT
VIN1 = 1VP-P, VIN2 = 0V
10
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S
MUX Amplifier
15V VIN1
+
LT1227 S/D VOUT
-
VOUT =1 VIN -15V 1.5k 5V
74C906
15V
VIN2
+
LT1227 S/D
-
-15V 1.5k
5V INPUT SELECT
5V
74HC04
74C906
1227 TA04
-50
-60
-70
-80
-90
TA03
1
10 FREQUENCY (MHz)
100
LT1227 TA05
LT1227 PACKAGE DESCRIPTIO U
J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
0.405 (10.287) MAX 8 7 6 5 0.005 (0.127) MIN 0.015 - 0.060 (0.381 - 1.524) 0.023 - 0.045 (0.584 - 1.143) HALF LEAD OPTION 0.045 - 0.068 (1.143 - 1.727) FULL LEAD OPTION 0.025 (0.635) RAD TYP 1 0.045 - 0.065 (1.143 - 1.651) 0.014 - 0.026 (0.360 - 0.660) 0.100 (2.54) BSC 0.125 3.175 MIN 2 3 0.220 - 0.310 (5.588 - 7.874) 4 0.200 (5.080) MAX
J8 1298
0.300 BSC (0.762 BSC)
CORNER LEADS OPTION (4 PLCS)
0.008 - 0.018 (0.203 - 0.457)
0 - 15
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS
OBSOLETE PACKAGE
N8 Package 8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
0.400* (10.160) MAX 8 7 6 5
0.300 - 0.325 (7.620 - 8.255)
0.045 - 0.065 (1.143 - 1.651)
0.130 0.005 (3.302 0.127)
0.009 - 0.015 (0.229 - 0.381)
0.065 (1.651) TYP 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 0.003 (0.457 0.076)
0.255 0.015* (6.477 0.381)
(
+0.035 0.325 -0.015 +0.889 8.255 -0.381
)
1
2
3
4
0.100 (2.54) BSC
N8 1098
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference 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
SO8 1298
1
2
3
4
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
LT1227
TYPICAL APPLICATI
Single Supply AC-Coupled Amplifier Noninverting
5V 4.7F
+
+
22F
10k
VIN
+
10k LT1227 VOUT
-
220F
51
510
VIN
AV = 11 BW = 14Hz to 60MHz
1227 TA08
Buffer with DC Nulling Loop
V+
180 10k 0.1F VIN 10k 2 3
180 10k
5
+
LT1227
1
6
VOUT
-
1.5k
100k 0.01F
+
100k LT1097
-
0.01F
1227 TA07
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS Miniature Packages: SOT-23, MSOP-8, SSOP-16 LT1395/LT1396/LT1397 Single/Dual/Quad 400MHz Current Feedback Amplifier
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
q
UO
S
Single Supply AC-Coupled Amplifier Inverting
15V 5V 4.7F AV = 510 10 RS + 51 10k 2N3904 100pF 75pF 3.579545MHz 150k LT1227 VOUT 15V 68pF 1k 100k 1N4148
3.58MHz Oscillator
BW = 14Hz to 60MHz
+ +
+
2.2F 10k
+ -
-
RS 220F 51 LT1227 510
1227 TA09
51 VOUT
CMOS Logic to Shutdown Interface
www.linear.com
+
+
-15V
1227 TA10
Optional Offset Nulling Circuit
RNULL
15V 3 7
V+ 3 7 10k 1 LT1227 2 5 4 V- 6 RNULL = 47k FOR VS = 5V RNULL = 150k FOR VS = 15V
1227 TA12
+
LT1227 6 8 4
+ -
2
-
-15V 10k
5V
2N3904
1227 TA11
1227fb LT/CP 1001 1.5K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1994

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