Patent ID: 6600344
Filing Date: 2003-07-29
Classification: H03K

Abstract:
An envelope detector circuit comprising:a capacitor; a first semiconductor device having a first input port that receives a first input signal and a first out put port coupled to the capacitor that provides current to charge a the capacitor in response to the first input signal; a first current drain coupled to the first semiconductor device and the capacitor, the first current drain conducting current away from the capacitor; and a second semiconductor device having a second input port that is set to a biasing voltage and a second output port that is coupled to the first output port of the first semiconductor device, wherein a voltage level of the first output port is indicative of a level of an envelope of the first input signal when the voltage level remains above a threshold voltage equaling the biasing voltage minus input port to output port voltage, of the second semiconductor device, and the voltage level otherwise does not fall below the a predetermined voltage.