A Tunable Upconverter Mixer With Image Rejection

A radio transmitter comprising at least first and second transmitter paths each coupled to an associated antenna to process a signal for substantially simultaneous transmission, each of the first and second transmitter paths comprising:

• a. a tunable upconversion mixer that receives as input a baseband or intermediate frequency signal to be upconverted, a local oscillator signal and a tuning control signal, and which upconverts the baseband or intermediate frequency signal to a frequency based on a frequency of the local oscillator signal and in response to the tuning control signal, resonates to pass signals in a desired passband corresponding to a desired sideband frequency, and which attenuates signals in an attenuation band that includes an image signal at an undesired image frequency, and outputting an upconverted signal;
• and
• b. at least one power amplifier coupled to the output of the tunable upconversion mixer to amplify the upconverted signal and couple an amplified signal to an associated antenna.

A method for upmixing a signal comprising steps of:

• a. applying a signal to be upmixed to a mixer circuit;
• and
• b. adjusting a tunable load circuit of the mixer circuit to control the passband of the tunable load circuit to coincide with an output signal at a desired frequency generated by the mixer circuit, wherein the tunable load circuit also attenuates signals in an attenuation band that includes an image signal generated by the mixer circuit.