Low-noise, high-linearity analog multiplier

A mixer, comprising:

• an input stage having an output node and operable to receive an input signal having a first frequency;
• an output stage having an input node coupled to the output node and operable to receive a mixing signal having a second frequency;
• and
• a filter coupled to the output node, operable at the first frequency to function as a tank circuit having a parallel resonant frequency that is substantially equal to the first frequency, and operable at a harmonic of the second frequency to function as a tank circuit having a series resonant frequency that is substantially equal to the harmonic of the second frequency.

A mixer, comprising:

• an input stage having first differential output nodes and operable to receive a differential input signal having a first frequency;
• an output stage having first differential input nodes respectively coupled to the differential output nodes and operable to receive a differential mixing signal having a second frequency;
• and
• a filter comprising an inductance directly coupling the differential output nodes and a capacitor coupled between the inductance and ground.

An electronic system, comprising:

• an oscillator operable to generate an oscillator signal having a second frequency;
• a mixer, comprising,
• an input stage having an output node and operable to receive an input signal having a first frequency,
• an output stage having a first input node coupled to the output node, having a second input node coupled to the oscillator, and having an output node, and
• a filter coupled to the first input node of the output stage, operable at the first frequency to function as a tank circuit having a parallel resonant frequency that is substantially equal to the first frequency, and operable at a harmonic of the second frequency to function as a tank circuit having a series resonant frequency substantially equal to the harmonic of the second frequency;
• and
• a load coupled to the output node of the output stage.

A method, comprising:

• mixing a first signal having a first frequency with a second signal having a second frequency to generate a resulting signal having a linearity and a component having a third frequency that is a harmonic of the second frequency;
• forming a parallel resonator having a parallel resonant frequency that is substantially equal to the first frequency;
• and
• forming a series resonator having a series resonant frequency substantially equal to the third frequency.

A method, comprising:

• mixing a first signal having a first frequency with a second signal having a second frequency with a mixer having an input stage coupled to an output stage at first and second nodes;
• forming between a reference node and the first and second nodes respective first and second parallel resonators each having a respective parallel resonant frequency that is substantially equal to the first frequency;
• and
• forming between the reference node and the first and second nodes respective first and second series resonators each having a respective series resonant frequency substantially equal to a harmonic of the second frequency.