This circuit uses a four-channel single-pole double-throw switch (ADG1611) and a resistor programmable instrumentation amplifier (AD620) to provide programmable gain. This circuit uses the industry standard low-cost AD620 and four-channel switch ADG1611 combination to achieve unparalleled performance and provide programmable gain characteristics and all the advantages of precision instrumentation amplifiers.
This document presents a programmable‑gain instrumentation‑amplifier circuit built from a four‑channel SPDT switch (ADG1611) and a precision instrumentation amplifier (AD620). The design uses four 0.1 % resistors and provides 16 selectable gain steps ranging from 1 to 10 000.
The note includes circuit diagrams, gain‑setting calculations, temperature‑drift data, and recommendations for PCB layout. It also lists alternative parts such as AD8221 and AD8220 that can replace the AD620, and points to related Analog Devices tutorials for layout and component selection. This manual is written in Chinese.
| Gain range | 1 to 10,000 |
|---|---|
| Switch on‑resistance (R_on) | typical 12 mΩ |
The circuit uses the ADG1611 four‑channel SPDT switch, the AD620 instrumentation amplifier, and four 0.1 % precision resistors to set the gain.