Published:2011/7/27 8:22:00 Author:Fiona | Keyword: selected gain, AC inverting amplifier, maintain bias | From:SeekIC
Circuit function
Dispense with amplified DC signal, it is in series with a blocking capacitor C1 at the input resistance,it can make the offset drift neglected. Even though the AC gain of amplifier is high, the output is still DC working, OP amplifier is only used as a simple amplification devices. Using R3 = R2 to achieve input current bias, but because of the DC gain L, therefore, this requirement is not too strict, such as the resistance of R2 is small, R2 can be removed. Increasing the capacitor C1, it can get low-frequency time constant, the frequency F0 is 1 / N, C1.R1, phase shift is 45 degrees, characteristic curve downs 1 / √ 2 (3DB). Therefore, to obtain flat characteristics, it should be in accordance with FO(1 / 3 ~ 1 / 5) to determine the C1 value.
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