Patent ID: 7209040

Claim:
An RFID circuit comprising: an RF carrier signal source; a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals; first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively; and first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal, further includes: second logic coupled to the first and second mixers and operable to determine whether the first and second baseband signals have the same polarity; third logic coupled to the first and second mixers and operable to determine which of the first and second baseband signals have a larger amplitude; and fourth logic coupled to the third logic operable to determine when signal having larger amplitude is switching from the first baseband signal to the second, and vice versa.