| 摘要 |
An amplifier circuit (300, 400, 500) employs negative feedback and a method (600) for providing such feedback to reduce distortion and/or an output impedance of the amplifier circuit, without adversely impacting the overall stability of the amplifier circuit. The amplifier circuit includes a forward path and a feedback path. The forward path includes at least one amplifier (301, 305) arranged in series with an output lowpass filter (307). The amplifier receives a feedback-compensated input signal and amplifies the input signal to produce an amplified signal. The feedback path includes a lowpass filter (311), a highpass filter (313), and a summing arrangement (315) that selectively include and exclude the output lowpass filter from the feedback loop. The feedback lowpass filter is operably coupled to an output of the output lowpass filter and attenuates high frequency components of the amplifier circuit's output signal to produce a lowpass-filtered feedback signal. The highpass filter is operably coupled to an input of the output lowpass filter and attenuates low frequency components of the output filter's input signal to produce a highpass-filtered feedback signal. The two filtered feedback signals are summed by the summing arrangement to produce a composite feedback signal for application to the forward path amplifier or amplifiers. |
