Cmos integrated signal detection circuit with high efficiency and performance

Abstract

In the present invention a semiconductor integrated circuit is described to perform signal detection in a data communication system. The circuit is configured such that the capacitors used in high pass filter and a low pass filter are CMOS capacitors. The capacitors are formed from transistors where the gate is one terminal of the capacitor and the source and drain connected together form the second terminal of the capacitor. The source and drain that are connected together are connected to a voltage bias in the circuit which prevents the capacitors from being in a “floating” circuit configuration. The signal detection is done in one stage where a high pass filter is in the source of the input transistors and a low pass filter is in the drain of the input transistors. A comparator connects to the drain circuitry of the input transistors which supplies and offset voltage to the comparator. The input signal must be of a specific frequency to be conducted through the filters and of specific amplitude to overcome the offset. The simplicity requires far few devices than previous signal detectors and facilitates the ability to handle high frequency signals.