| 摘要 |
<p>A power controller includes a closed loop system (10) having a summer (12) to sum an input signal with a derived output signal to produce a difference signal. A comparator (22) compares the difference signal with a reference signal to produce a digital signal representative of the polarity difference between the difference signal and the reference signal. Two switching networks (30) respond to the digital signal to produce high energy outputs representative of the digital signal which are used to reduce the level of the difference signal in a frequency band of interest at the comparator (22). A low pass filter (32) between the high energy outputs and the comparator (22) attenuates high frequency noise. A low-pass filter (32) of at least the third order, connected in the closed loop, enhances the signal to noise ratio. A specific application of the power controller is a power amplifier with the input signal in the audio frequency range.</p> |
