Patent ID: 7075372
Filing Date: 2006-07-11
Classification: H03F,H03G

Abstract:
1. A programmable automatic signal amplitude control circuit, comprising: a variable gain amplifier, gain of which is maintained by received control signals, outputting an out signal; a negative feedback circuit, comprising: a first circuit, set between a first voltage source and a first node, the first node coupled to an output terminal of the negative feedback circuit; and a second circuit, set between the first node and a second voltage source, wherein the second circuit comprises: a peak detector, receiving the output signal and detecting the amplitude level of the input signal to output a rectifying signal; a level adjustable amplifier, receiving the rectifying signal for conversion to a voltage signal; and a voltage/current converter, receiving the voltage signal for conversion to a corresponding second current, whereby the voltage signal increases, the second current increases; and a capacitor, receiving a third current to generate the control signal, wherein the third current is defined by a differential between a first current output from the first circuit and the second current; the output signal of the variable gain amplifier further comprising a setup amplitude, such that when the amplitude of the output signal is lower than the setup amplitude, the second current decreases, such that the first current exceeds the second current, and the amplitude of the output signal increases to approach the setup amplitude; and when the amplitude of the output signal exceeds the setup amplitude, the second current increases, such that the first current is smaller than the second current, and the amplitude of the output signal decreases to approach to the setup amplitude.