Instrumentation amplifier that takes a small differential signal, from a bridge, thermocouple, or shunt, and amplifies it against a reference, rejecting the common-mode voltage. One external resistor between the RG pins sets the gain from 1 to 1000, and the REF pin positions the output within a single supply, so it works on 3 to 12 V rails with a rail-to-rail output. It runs from a single or dual supply at low current. A standard front end for sensor bridges.

Pinout

Pin	Name	Type	Function
1	-RG	passive	Inverting terminal of the external gain-setting resistor R_G. Connect R_G between Pin 1 and Pin 8 to set gain G = 1 + 100 kΩ/R_G (1 to 1000). Leave open for unity gain.
2	-IN	input	Inverting in-amp input. Differential input pair with Pin 3 (+IN); common-mode range extends 150 mV below -V_S. Input bias current typ 17 nA.
3	+IN	input	Noninverting in-amp input. Differential input pair with Pin 2 (-IN); common-mode range extends 150 mV below -V_S. Input bias current typ 17 nA.
4	-VS	power_in	Negative supply terminal. Connect to ground for single-supply operation (2.7 V to 12 V total) or to a negative rail for dual-supply operation (±2.5 V to ±6 V). Quiescent current 550 µA max.
5	REF	input	In-amp output reference input. Sets the DC offset of the output; drive from a low-impedance source. V_REF establishes the common-mode voltage of the output signal.
6	OUTPUT	output	In-amp output. Rail-to-rail swing; with R_L = 10 kΩ, output swings to within 0.2 V of each rail. 800 kHz small-signal bandwidth at G = 1.
7	+VS	power_in	Positive supply terminal. Total supply (+V_S to -V_S) 2.7 V to 12 V. Bypass locally with a 0.1 µF ceramic capacitor to ground.
8	+RG	passive	Noninverting terminal of the external gain-setting resistor R_G. Connect R_G between Pin 1 and Pin 8; leave open for G = 1.

Key specifications

Parameter	Value
Type	Instrumentation amplifier
Gain	1 to 1000 (one external resistor)
Supply	Single 3-12 V or dual +/-2.5 to +/-6 V
Output	Rail-to-rail
CMRR	90 dB (min, G=1)
Supply current	575 uA (max)
Package	SOIC-8

Ordering variants

AD623ARZ (SOIC-8)
AD623ANZ (PDIP-8)
AD623ARMZ (MSOP-8)

CAD (KiCad official)

Symbol: Amplifier_Instrumentation:AD623 (KiCad official)
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Analog Devices datasheet (32 pp, sha256 44f12008011b61f7, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF