Patent ID: 8665000

Claim:
A method of frequency down-converting an input signal having a first frequency to an output signal having a second frequency, comprising: generating a first local oscillator signal as a square wave having: a cycle period corresponding to the sum of or the difference between the first and second frequencies; and a duty cycle of 1/3 or 2/3; a consistent polarity in the fraction of the cycle period where it is active; generating a second local oscillator signal as a modified square wave having: a cycle period the same as the first local oscillator signal; and a duty cycle of 2/3, of which 1/3 of the cycle period has a positive amplitude and another 1/3 of the cycle period has a negative amplitude; wherein the first and second local oscillator signals are generated such that they have a phase shift of π/2 between them, such that the first local oscillator signal has a delay of 1/4 of the cycle period compared to the second local oscillator signal; mixing the input signal with the first local oscillator signal to form a first down-converted signal; mixing the input signal with the second local oscillator signal to form a second down-converted signal; multiplying at least one of the down-converted signals by a pre-calculated factor; and adding the two resulting down-converted signals to form the output signal.