The AD844 is a high speed monolithic operational amplifier
fabricated using the Analog Devices, Inc., junction isolated complementary bipolar (CB) process. It combines high bandwidth and very fast large signal response with excellent dc performance. Although optimized for use in current-to-voltage applications and as an inverting mode amplifier, it is also suitable for use in many noninverting applications.
The AD844 can be used in place of traditional op amps, but its current feedback architecture results in much better ac performance, high linearity, and an exceptionally clean pulse response.
This type of op amp provides a closed-loop bandwidth that is
determined primarily by the feedback resistor and is almost independent of the closed-loop gain. The AD844 is free from the slew rate limitations inherent in traditional op amps and other current-feedback op amps. Peak output rate of change can be over 2000 V/μs for a full 20 V output step. Settling time is
typically 100 ns to 0.1%, and essentially independent of gain.
The AD844 can drive 50 Ω loads to ±2.5 V with low distortion and is short-circuit protected to 80 mA.
The AD844 is available in four performance grades and three
package options. In the 16-lead SOIC (RW) package, the AD844J is specified for the commercial temperature range of 0°C to 70°C.
The AD844A and AD844B are specified for the industrial
temperature range of −40°C to +85°C and are available in the
CERDIP (Q) package. The AD844A is also available in an 8-lead PDIP (N). The AD844S is specified over the military temperature range of −55°C to +125°C. It is available in the 8-lead CERDIP
(Q) package. A and S grade chips and devices processed to MIL-STD-883B, Rev. C are also available.
Product Highlights
- The AD844 is a versatile, low cost component providing an excellent combination of ac and dc performance.
- It is essentially free from slew rate limitations. Rise and fall times are essentially independent of output level.
- The AD844 can be operated from ±4.5 V to ±18 V power supplies and is capable of driving loads down to 50 Ω, as well as driving very large capacitive loads using an external network.
- The offset voltage and input bias currents of the AD844 are laser trimmed to minimize dc errors; VOS drift is typically 1 μV/°C and bias current drift is typically 9 nA/°C.
- The AD844 exhibits excellent differential gain and differential phase characteristics, making it suitable for a variety of video applications with bandwidths up to 60 MHz.
- The AD844 combines low distortion, low noise, and low drift with wide bandwidth, making it outstanding as an input amplifier for flash analog-to-digital converters (ADCs).
Applications
- Flash ADC input amplifiers
- High speed current DAC interfaces
- Video buffers and cable drivers
- Pulse amplifiers
