The offset zeroing circuit of differential amplifier

Published:2011/5/12 5:08:00 Author:Rebekka | Keyword: differential amplifier, offset zeroing | From:SeekIC

The offset zeroing circuit of differential amplifier is shown as above. When you lead the offset adjusting voltage to the differential amplifier circuit, it should not affect the balance of differential mode signal. In the circuit high-voltage divider ratio composed of R3 and R5. It provides variable potential to the right end of R2. Then it is passes R1 and R2 partial pressure. It gains the offset adjusting voltage at the inverting input of op amp. Generally the value of resistance R5 is small, its purpose is to raise partial pressure ratio. In order to obtain a high accuracy, sometimes in order to reduce the introduction of the common mode error, you need to adjust R2' to achieve the purpose. 　R2/R1=(R2'+R5)/R1' The circuit is shown in Fig. Its offset adjust voltage range determined by the following:Offset voltage range = VD (R5 / (R3 + R5)) (R1 '/ R1' + R2 ')Based on the data graph, the offset adjustment range is ± 15mV.



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