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Part: CA3280AF3
Category:
Analog & Mixed-Signal Processing
-> Amplifiers
-> Transconductance & Transimpedance Amplifiers
Description: Dual, 9mhz, Operational Transconductance Amplifier ( Ota )
Company: Intersil Corporation
Datasheet: Download CA3280AF3 datasheet File size : 1382 kB
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Datasheet text preview:
CA3280, CA3280A
D a ta Sheet September 1998 File Number 1174.4
Dual, 9MHz, Operational Transconductance Amplifier (OTA)
The CA3280 and CA3280A types consist of two variable operational amplifiers that are designed to substantially reduce the initial input offset voltage and the offset voltage variation with respect to changes in programming current. This design results in reduced "AGC thump," an objectionable characteristic of many AGC systems. Interdigitation, or crosscoupling, of critical portions of the circuit reduces the amplifier dependence upon thermal and processing variables. The CA3280 has all the generic characteristics of an operational voltage amplifier except that the forward transfer characteristics is best described by transconductance rather than voltage gain, and the output is current, not voltage. The magnitude of the output current is equal to the product of transconductance and the input voltage. This type of operational transconductance amplifier was first introduced in 1969, and it has since gained wide acceptance as a gateable, gain controlled building block for instrumentation and audio applications, such as linearization of transducer outputs, standardization of widely changing signals for data processing, multiplexing, instrumentation amplifiers operating from the nanopower range to high current and high speed comparators. For additional application information on this device and on OTAs in general, please refer to Application Notes: AN6818, AN6668, and AN6077.
Features
· Low Initial Input Offset Voltage: 500µV (Max) (CA3280A) · Low Offset Voltage Change vs IABC: <500µV (Typ) for All Types · Low Offset Voltage Drift: 5µV/oC (Max) (CA3280A) · Excellent Matching of the Two Amplifiers for All Characteristics · Internal Current-Driven Linearizing Diodes Reduce the External Input Current to an Offset Component · Flexible Supply Voltage Range. . . . . . . . . . . ±2V to ±15V
Applications
· Voltage Controlled Amplifiers · Voltage Controlled Oscillators · Multipliers · Demodulators · Sample and Hold · Instrumentation Amplifiers · Function Generators · Triangle Wave-to-Sine Wave Converters · Comparators · Audio Preamplifier
Pinout
CA3280 (PDIP, CERDIP) TOP VIEW
ID, A1 1 EMITTER, A1 2 IABC, A1 3 V- 4 NC 5 IABC, A2 6 EMITTER, A2 7 ID, A2 8 A2 16 +IN, A1 15 -IN, A1 14 V+, A1 13 OUT, A1 12 OUT, A2 11 V+, A2
Ordering Information
PART NUMBER CA3280AE CA3280E CA3280AF3 TEMP. RANGE (oC) -55 to 125 0 to 70 -55 to 125 PACKAGE 16 Ld PDIP 16 Ld PDIP 16 Ld CERDIP PKG. NO. E16.3 E16.3 F16.3
A1
+
-
+
10 -IN, A2 9 +IN, A2
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Copyright © Intersil Corporation 1999
CA3280, CA3280A
.
Functional Diagram
1/2 CA3280 14 11
-
15 10 7 2
+ 16 9 2K 1 8 4 3 6 2K 13 12
2
CA3280, CA3280A
Absolute Maximum Ratings
Supply Voltage (Between V+ and V-). . . . . . . . . . . . . . . . . . . . +36V Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V Input Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V+ to VInput Current at ID = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100µA Amplifier Bias Current (IABC) . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA Output Short Circuit Duration (Note 1). . . . . . . . . . . . . . . . Indefinite Linearizing Diode Bias Current, ID . . . . . . . . . . . . . . . . . . . . . . . 5mA Peak Input Current with Linearizing Diode. . . . . . . . . . . . . . . . . . ±ID
Thermal Information
Thermal Resistance (Typical, Note 2) JA (oC/W) JC (oC/W) CERDIP Package. . . . . . . . . . . . . . . . . 65 16 PDIP Package . . . . . . . . . . . . . . . . . . . 100 N/A Maximum Junction Temperature (CERDIP Package). . . . . . . . .175oC Maximum Junction Temperature (Plastic Package) . . . . . . . .150oC Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC
Operating Conditions
Temperature Range CA3280 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to 70oC CA3280A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55oC to 125oC Supply Voltage Range (Typ) . . . . . . . . . . . . . . . . . . . . . ±2V to ±15V
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTES: 1. Short circuit may be applied to ground or to either supply. 2. JA is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
PARAMETER Input Offset Voltage
For Equipment Design, at TA = 25oC, VSUPPLY = ±15V, Unless Otherwise Specified CA3280 SYMBOL VIO TEST CONDITIONS IABC = 1mA IABC = 100µA IABC = 10µA IABC = 1mA to 10µA, TA = Full Temp. Range MIN 12 12 IABC = 5µA 12 12 IABC = 100µA IABC = 500µA 10Hz 1kHz 10kHz -13 -Z 350 -350 3 -3 TYP 0.7 0.8 0.5 5 1.2 13.7 -14.3 13.9 -14.5 20 8 7 0.3 1.8 3 410 -410 4.1 -4.1 MAX 3 3 3 4 1 13 0.7 5 8 650 -650 7 -7 MIN 12.5 -13.3 12.5 -13.5 -13 350 -350 3 -3 CA3280A TYP 0.25 0.8 0.5 3 1.2 13.7 -14.3 13.9 -14.5 20 8 7 0.3 1.8 3 410 -410 4.1 -4.1 MAX 0.5 0.5 0.5 1.5 1 5 13 0.7 5 8 650 -650 7 -7 UNITS mV mV mV mV mV µV/oC V V V V V V nV/Hz nV/Hz nV/Hz µA µA µA µA µA µA µA
Input Offset Voltage Drift
|VIO|
IABC = 1µA to 1mA IABC = 100µA, TA = Full Temperature Range
Amplifier Bias Voltage Peak Output Voltage
VABC VOM+ VOMVOM+ VOM-
IABC = 100µA IABC = 500mA
Common Mode Input Voltage Range Noise Voltage
VICR eN
Input Offset Current Input Bias Current
IIO IIB
IABC = 500µA IABC = 500µA IABC = 500µA, TA = Full Temperature Range
Peak Output Current
IOM+ IOMIOM+ IOM-
IABC = 500µA
Source Sink
IABC = 5µA
Source Sink
3
CA3280, CA3280A
Electrical Specifications
PARAMETER Peak Output Current Sink and Source Linearization Diodes Offset Current Dynamic Impedance Diode Network Supply Current Amplifier Supply Current (Per Amplifier) Amplifier Output Leakage Current I+ IOL For Equipment Design, at TA = 25oC, VSUPPLY = ±15V, Unless Otherwise Specified (Continued) CA3280 SYMBOL IOM - , IOM+ TEST CONDITIONS IABC = 500µA, TA = Full Temperature Range ID = 100µA ID = 10µA ID = 100µA IABC = 100µA IABC = 500µA IABC = 0, VO = 0V IABC = 0, VO = 30V Common Mode Rejection Ratio Power Supply Rejection Ratio Open Loop Voltage Gain CMRR PSRR AOL IABC = 100µA IABC = 100µA IABC = 100µA, RL = , VO = 20VP-P IABC = 50µA, Large Signal IABC = 1mA, Small Signal IABC = 10µA f = 1kHz THD fT SR CI CO Output Resistance RO IABC = 100µA f = 1kHz, IABC = 1.5mA, RL = 15k, VO = 20VP-P IABC = 1mA, RL = 100 IABC = 1mA IABC = 100µA Input Output MIN 350 250 80 86 94 50 0.5 TYP 450 10 0.5 700 400 2 0.015 0.15 100 105 100 100 0.8 16 94 0.4 9 125 4.5 7.5 63 MAX 550 1 800 2.4 0.1 1 1.2 22 MIN 350 250 94 94 94 50 0.5 CA3280A TYP 450 10 0.5 700 400 2 0.015 0.15 100 105 100 100 0.8 16 94 0.4 9 125 4.5 7.5 63 MAX 550 1 800 2.4 0.1 1 1.2 22 UNITS µA µA µA µA mA nA nA dB dB dB kV/V mS mS M dB % MHz V/µs pF pF M
Forward Transconductance
GM gM
Input Resistance Channel Separation Open Loop Total Harmonic Distortion Bandwidth Slew Rate, Open Loop Capacitance
RI
Test Circuits and Waveforms
V+ +30V INPUT 16 30V 0V I TEST POINT 14 15 14 + 1/2 CA3280 0.1µF OUTPUT 13 3 30k V30k V+ 10k
1/2 CA3280 + 4 1 3 1k 13 15
4
16
1k
0.1 µF
FIGURE 1. LEAKAGE CURRENT TEST CIRCUIT
FIGURE 2. CHANNEL SEPARATION TEST CIRCUIT
4
CA3280, CA3280A Test Circuits and Waveforms
(Continued)
V+ 15V 14 10k 16 1/2 CA3280 15 4 3 1 V-15V IABC IDIODE VIN 1k IOUT 13
10k
IABC = 650µA, ID = 200µA; Vertical = 200µA/Div.; Horizontal = 1V/Div.
FIGURE 3A. EFFECTS OF DIODE LINEARIZATION, WITH DIODE PROGRAMMING TERMINAL ACTIVE
V+ 15V 11 10k 9 1/2 CA3280 10 6 4 8 IDIODE IABC V-15V VIN 1k 12 IOUT
10k
IABC = 650µA; ID = 0; Vertical = 200µA/Div.; Horizontal = 25mV/Div. FIGURE 3B. WITH DIODE PROGRAMMING TERMINAL CUTOFF FIGURE 3. CA3280 TRANSFER CHARACTERISTICS
Application Information
Figures 4 and 5 show the equivalent circuits for the current source and linearization diodes in the CA3280. The current through the linearization network is approximately equal to the programming current. There are several advantages to driving these diodes with a current source. First, only the offset current from the biasing network flows through the input resistor. Second, another input is provided to extend the gain control dynamic range. And third, the input is truly differential and can accept signals within the common mode range of the CA3280. network requires ratio matching of 0.01% or trimming for 80dB of common-mode rejection. The CA3280, with its excellent common mode rejection ratio, is capable of converting a small (±25mV) differential input signal to a single-ended output without the need for a matched resistor network. Figure 7 shows the CA3280 in a typical gain control application. Gain control can be performed with the amplifier bias current (lABC). With no diode bias current, the gain is merely gMRL. For example, with an lABC of 1mA, the gM is approximately 16mS. With the CA3280 operating into a 5k resistor, the gain is 80. The need for external buffers can be eliminated by the use of low value load resistors, but the resulting increase in the required amplifier bias current reduces the input impedance
Typical Applications
The structure of the variable operational amplifier eliminates the need for matched resistor networks in differential to single ended converters, as shown in Figure 6. A matched resistor 5
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