Mixer circuit and method

A method for reducing or eliminating the effects of mixer leakage, comprising:

• mixing input signals to generate an output signal using a frequency mixer, wherein the output signal exhibits a leakage component associated with the frequency mixer;
• producing a correction signal and applying the correction signal to the frequency mixer in addition to the input signals;
• up-converting a test signal by mixing it with the output signal of the frequency mixer;
• down-converting the up-converted signal;
• detecting a spurious signal in the down-converted signal that is due to a leakage component of the frequency mixer;
• and
• selecting the correction signal to reduce or eliminate the leakage signal.

A mixer circuit, comprising:

• a frequency mixer configured to mix input signals and generate an output signal;
• a signal generator configured to produce a correction signal and provide the correction signal to the frequency mixer for addition to the input signals;
• an up-conversion mixer configured to up-convert a test signal by mixing it with the output signal of the frequency mixer to form an up-converted signal;
• a down-conversion mixer configured to down-convert the up-converted output signal of the up-conversion mixer;
• a signal detector configured to detect a spurious signal in the output signal of the down-conversion mixer;
• and
• a control unit, coupled to the signal generator and the signal detector, configured to control the signal generator to reduce or eliminate the spurious signal.

A method for reducing or eliminating a spurious signal, comprising:

• mixing input signals to generate an output signal by using a frequency mixer;
• producing a correction signal and applying the correction signal to the frequency mixer in addition to the input signals;
• up-converting a test signal by mixing it with the output signal of the frequency mixer;
• down-converting the up-converted signal;
• detecting a spurious signal in the down-converted signal;
• and
• selecting the correction signal to reduce or eliminate the spurious signal.

A radio transmitter comprising:

• a signal generator configured to generate a correction signal;
• a frequency synthesizer configured to generate a local oscillator frequency signal by mixing a first frequency signal, to which the correction signal is added, with a second frequency signal;
• an up-conversion mixer configured to up-convert a test signal by mixing it with the local oscillator frequency signal;
• a down-conversion mixer configured to down-convert the output signal of the up-conversion mixer;
• a signal detector configured to detect a spurious signal in the output signal of the down-conversion mixer;
• and
• control means, coupled to the signal generator and the signal detector, and operable to control the signal generator to reduce or eliminate the spurious signal detected by the signal detector.

In a radio transmitter, a method comprising:

• producing a correction signal;
• producing a local oscillator frequency signal by mixing a first frequency signal, to which the correction signal is added, with a second frequency signal;
• up-converting a test signal by mixing it with the local oscillator frequency signal;
• down-converting the up-converted signal;
• detecting a spurious signal in the down-converted signal;
• and
• selecting the correction signal to reduce or eliminate the detected spurious signal.