The AD640 is a complete monolithic logarithmic amplifier. A single chip contains five stages, each having a gain of 10 dB and a bandwidth of 350 MHz. The signal path is fully differential and direct-coupled. The logarithmic slope, intercept, and AC response are stable over full military temperature range.
The AD640 is a monolithic logarithmic amplifier that provides a fully calibrated, DC‑coupled signal path. It consists of five cascaded 10 dB gain stages, each with a 350 MHz bandwidth, delivering a dual‑polarity current output scaled at 1 mA per decade. The device operates from a 4.5 V to 7.5 V supply and consumes about 220 mW at 5 V.
Three temperature‑rated variants are available: AD640B for industrial (-40 °C to +85 °C), AD640T for military (-55 °C to +125 °C), and AD640J for commercial (0 °C to +70 °C). Applications include radar, sonar, ultrasonic, audio systems, precision instrumentation, and power measurement.
| Number of Stages | 5 |
|---|---|
| Input Resistance (Differential) | 500 Ω |
The differential input resistance is 500 Ω.
AD640B is rated –40 °C to +85 °C, AD640T –55 °C to +125 °C, and AD640J 0 °C to +70 °C.