a FEATURES Matched Offset Voltage Matched Offset Voltage Over Temperature Matched Bias Currents Crosstalk –124 dB at 1 kHz Low Bias Current: 35 pA max Warmed Up Low Offset Voltage: 500 V max Low Input Voltage Noise: 2 V p High Slew Rate: 13 V/s Low Quiescent Current: 4.5 mA max Fast Settling to ؎0.01%: 3 s Low Total Harmonic Distortion: 0.0015% at 1 kHz Standard Dual Amplifier Pinout Available in Hermetic Metal Can Package and Chip Form MIL-STD-883B Processing Available Single Version Available: AD544 PRODUCT DESCRIPTION
The AD644 is a pair of matched high speed monolithic FET input operational amplifiers fabricated with the most advanced bipolar, JFET and laser-trimming technologies. The AD644 offers matched bias currents that are significantly lower than currently available monolithic dual BiFET operational amplifiers: 35 pA max, matched to 25 pA for the AD644K and L, 75 pA max matched to 35 pA for the AD644J and S. In addition, the offset voltage is laser trimmed to less than 0.5 mV, and matched to 0.25 mV for the AD644L, 1.0 mV and matched to 0.5 mV for the AD644K, utilizing Analog Devices’ laser-wafer trimming (LWT) process. The tight matching and temperature tracking between the operational amplifiers is achieved by ion-implanted JFETs and laser-wafer trimming. Ion-implantation permits the fabrication of precision, matched JFETs on a monolithic bipolar chip. This process optimizes the ability to produce matched amplifiers which have lower initial bias currents than other popular BiFET op amps. Laser-wafer trimming each amplifier’s input offset voltage assures tight initial match and superior IC processing guarantees offset voltage tracking over the temperature range. The AD644 is recommended for applications in which both excellent ac and dc performance is required. The matched amplifiers provide a low cost solution to true wideband instrumentation amplifiers, low dc drift active filters and output amplifiers for four quadrant multiplying D/A converters such as the AD7541, 12-bit CMOS DAC. The AD644 is available in four versions: the “J”, “K” and “L” are specified over the 0°C to +70°C temperature range and the “S” over the –55°C to +125°C operating temperature range.
Dual High Speed, Implanted BiFET Op Amp AD644 PIN CONFIGURATION
+V AMPLIFIER NO. 1
AMPLIFIER NO. 2 8
INVERTING INPUT NONINVERTING INPUT
TOP VIEW 4
–V NOTE: PIN 4 CONNECTED TO CASE
All devices are packaged in the hermetically sealed, TO-99 metal can or available in chip form. PRODUCT HIGHLIGHTS
1. The AD644 has tight side to side matching specifications to ensure high performance without matching individual devices. 2. Analog Devices, unlike some manufacturers, specifies each device for the maximum bias current at either input in the warmed-up condition, thus assuring the user that the AD644 will meet its published specifications in actual use. 3. Laser-wafer-trimming reduces offset voltage to as low as 0.5 mV max matched side to side to 0.25 mV (AD644L), thus eliminating the need for external nulling. 4. Improved bipolar and JFET processing on the AD644 result in the lowest matched bias current available in a high speed monolithic FET op amp. 5. Low voltage noise (2 µV p) and high open loop gain enhance the AD644’s performance as a precision op amp. 6. The high slew rate (13.0 V/µs) and fast settling time to 0.01% (3.0 µs) make the AD644 ideal for D/A, A/D, samplehold circuits and dual high speed integrators. 7. Low harmonic distortion (0.0015%) and low crosstalk (–124 dB) make the AD644 an ideal choice for stereo audio applications. 8. The standard dual amplifier pin out allows the AD644 to replace lower performance duals without redesign. 9. The AD644 is available in chip form.
REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
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