Patent ID: 7579906

Claim:
A method for demodulating radio frequency amplitude modulated signals, said method comprising the steps of: providing a demodulator circuit that comprises a +ve envelope detector circuit, a first low pass filter having an input coupled to an output of said +ve envelope detector circuit, a second low pass filter having an input coupled to an output of said first low pass filter, and a latched comparator circuit having a first input coupled to an output of said first low pass filter and a second input coupled to an output of said second low pass filter; receiving a radio frequency amplitude modulated signal in said +ve envelope detector circuit; detecting a +ve envelope signal with said +ve envelope detector circuit; providing said +ve envelope signal to a said first low pass filter; filtering said +ve envelope signal with said first low pass filter; and providing said filtered +ve envelope signal to said first input of said latched comparator circuit; providing said filtered +ve envelope signal to said second low pass filter; and creating a delayed version of said +ve envelope signal using said second low pass filter; providing said delayed version of said +ve envelope signal to said second input of said latched comparator circuit; and detecting in said latched comparator circuit a transition in said radio frequency amplitude modulated signal using a voltage difference between said +ve envelope signal from said first low pass filter and said delayed +ve envelope signal from said second low pass filter.