On-chip harmonic filtering for radio frequency (RF) communications

A method to operate an integrated circuit, comprising:

• passing a radio frequency (RF) signal through a circuit, which is coupled between a first node and a connection pad for the integrated circuit to provide harmonic rejection filtering of the RF signal and to provide impedance matching with respect to a load coupled to the connection pad, the circuit comprising:
• a first inductance coupled between the first node and a second node;
• a first capacitance coupled between the first node and the second node in parallel with the first inductance, wherein a total capacitance value between the first node and the second node is a non-variable capacitance value;
• a variable second capacitance coupled between the second node and ground;
• and
• a second inductance coupled between the second node and the connection pad for the integrated circuit;
• wherein the first inductance, the first capacitance and the variable second capacitance form a resonant circuit that provides the harmonic rejection filtering of the RF signal by rejecting one or more harmonic frequencies of the RF signal;
• and
• controlling a capacitance amount for the variable second capacitance to:
• (a) determine the impedance matching provided by the circuit, and (b) tune a notch frequency for the harmonic rejection filtering provided by the resonant circuit.