Ultra-wideband up-conversion N-path mixer with bandpass rejection of odd harmonic frequencies

A radio frequency (RF) receiver circuit comprising:

• an RF input terminal configured to receive an RF input signal comprising a desired signal having a center frequency and an undesired signal having an undesired frequency;
• N up-conversion paths configured to provide N filtered up-converted signals, wherein an nth up-conversion path comprises an nth transistor and an nth bandpass filter, where the subscript n is an integer 1 to N and N is an integer of 2 or more and corresponds to a number of up-conversion paths;
• and
• a local oscillator (LO) signal generator configured to provide N reference voltage signals having an LO frequency:
• wherein:
• the nth transistor has a source coupled to the RF input terminal, and a drain coupled to the nth bandpass filter, and a gate coupled to the LO signal generator to receive an nth reference voltage signal;
• the drain of the nth transistor is configured to provide an nth mixed signal in response to the nth reference voltage signal at the gate of the nth transistor and the RF input signal at the source of the nth transistor;
• the nth bandpass filter is configured at a fixed bandpass frequency to pass a first frequency component and reject a second frequency component in the nth mixed signal to provide an nth filtered up-converted signals, wherein the first frequency component is associated with the center frequency and the second frequency component is associated with the undesired frequency of the RF input signal;
• and
• the fixed bandpass frequency is substantially equal to the LO frequency plus the center frequency.

A method of rejecting an undesired frequency in a radio frequency (RF) input signal having a center frequency and the undesired frequency, the method comprising:

• receiving the RF input signal comprising the center frequency and the undesired frequency;
• generating a plurality of local oscillator (LO) reference voltage signals having an LO frequency:
• associating a plurality of transistors with the plurality of LO reference voltage signals and the RF input signal;
• mixing the RF input signal and one of the plurality of LO reference voltage signals associated with one of the transistors in the plurality of transistors that is configured in a saturation mode to generate a mixed signal having a first frequency component associated with the center frequency and a second frequency component associated with the undesired frequency;
• and
• setting a fixed bandpass frequency to pass the first frequency component and reject the second frequency component in the mixed signal to provide a filtered up-converted signal, wherein the fixed bandpass frequency is substantially equal to the LO frequency plus the center frequency.