AD8221 Precision Strain Gage Amplifier

AD8221 is an excellent candidate for bridge measurement because it has low offset and high CMRR over frequency. The bridge can be directly connected to the inputs of the amplifier as shown in figure below. The AD8221 is a gain programmable, in its class, high performance instrumentation amplifier that delivers the industry’s highest CMRR over frequency.

Today, the CMRR of instrumentation amplifiers on the market falls off at 200Hz. In contrast, a minimum CMRR of 80 dB to 10 kHz for all grades at G=1 is maintained by the AD8221. The AD8221 is greatly simplifying filter requirements because high CMRR over frequency allows the AD8221 to reject wideband interference and line harmonics. Possible applications include biomedical analysis, precision data acquisition, and aerospace instrumentation. [Circuit’s schematic diagram source:]