| 摘要 |
Current mirror circuits and methods, and an amplifier using same, are provided in which the output of the current mirror is reduced to zero when the input current falls below a predetermined threshold. An offset current is subtracted from the input (or reference) current at input currents below the threshold. Otherwise, the offset current source is turned off. Thus, the output current can be reduced to zero, even if there is a small input current, without distorting the input-output relationship over the majority of the range of operation of the current mirror. An amplifier with two current-feedback complementary input stages (or fader circuit) is also provided which includes a gain control circuit that uses the current mirror circuits of the present invention to ensure that each input can be fully attenuated. The gain control circuit causes one of the two inputs to be fully attenuated when a control voltage passes one of two thresholds that are offset by predetermined amounts from the corresponding endpoints of the control voltage range. The amplifier thus provides an accurate, undistorted gain value for a given control voltage over the majority of its range of operation.
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