Programmable mixer for reducing local oscillator feedthrough and radio applications thereof

A wireless transmitter, comprising:

• a baseband processor operable to generate a plurality of differential input signals;
• an RF front end comprising a mixer module operable to receive the differential input signals and differential local oscillator inputs and to generate a mixed signal output there from, the mixer having a plurality of operating states wherein each of the plurality of operating states corresponds to a magnitude of local oscillator leakage signal component passed by the mixer module;
• a power amplifier receiving the output of the mixer and generating an outbound RF signal;
• a signal strength detector operably connected to measure the local oscillator leakage signal component of the signal passed by the power amplifier;
• a compensation module operable to generate a control signal to set the operational parameters of the mixer to the operating state that minimizes the magnitude of the local oscillator leakage signal component of the signal passed by the mixer.

An RF transceiver, comprising:

• an RF front end receiver section;
• and
• an RF front end transmitter section comprising:
• a mixer module operable to receive differential input signals and differential local oscillator inputs and to generate a mixed signal output there from, the mixer having a plurality of operating states wherein each of the plurality of operating states corresponds to a magnitude of local oscillator leakage signal component passed by the mixer module;
• a power amplifier receiving the output of the mixer and generating an outbound RF signal;
• a signal strength detector operably connected to measure the local oscillator leakage signal component of the signal passed by the power amplifier;
• and
• a compensation module operable to generate a control signal to set the operational parameters of the mixer to the operating state that minimizes the magnitude of the local oscillator leakage signal component of the signal passed by the mixer.

A method of optimizing a mixer to reduce local oscillator feedthrough, comprising:

• (a) setting the local oscillator to a calibration frequency;
• (b) setting the input signals to the mixer to a known input signal state;
• (c) setting control parameters of the mixer to a first known state within a plurality of possible mixer states;
• (d) measuring the local oscillator leakage signal strength corresponding to the mixer control parameters;
• (e) repeating steps (a)-(d) until the local oscillator leakage has been measured at all possible mixer control parameter states;
• and
• (f) setting the mixer control parameters to the state corresponding to the lowest magnitude of local oscillator leakage signal.

A method of optimizing a mixer to reduce local oscillator feedthrough, comprising:

• (a) setting the local oscillator to a calibration frequency;
• (b) setting the input signals to the mixer to a known input signal state;
• (c) setting control parameters of the mixer to a first known state within a plurality of possible mixer states;
• (d) measuring the local oscillator leakage signal strength corresponding to the mixer control parameters;
• (e) comparing the local oscillator leakage signal strength to predetermined threshold criteria;
• (e) repeating steps (a)-(d) to measure the local oscillator leakage at successive states within the plurality of possible mixer control parameter states;
• and
• (f) setting the mixer control parameters to the first state within the plurality of possible control states that corresponding to the local oscillator leakage signal strength that meets the predetermined threshold criteria.