Patent ID: 7343135

Claim:
A demodulator circuit for emulating the down conversion of an input signal x(t) with a local oscillator (LO) signal, said demodulator circuit comprising: a first mixer for receiving said input signal x(t), and mixing said input signal x(t) with a multi-tonal mixing signal φ 1 , to generate an output signal φ 1 x(t); a second mixer for receiving said signal φ 1 x(t) as an input, and mixing said signal φ 1 x(t) with a mono-tonal mixing signal φ 2 , to generate an output signal φ 1 φ 2 (t); a first signal generator for generating an oscillator signal f 1 ; a second signal generator for generating said mono-tonal mixing signal φ 2 , where the frequency of f 1 is a multiple of the frequency of φ 2 ; and a logic circuit for receiving said oscillator signal f 1 and said mono-tonal mixing signal φ 2 , and generating said multi-tonal mixing signal φ 1 , where φ 1 *φ 2 has significant power at the frequency of said local oscillator signal being emulated, neither of said φ 1 nor said φ 2 having significant power at the carrier frequency of said input signal x(t) or said LO signal being emulated.