System and method for multiple supply IQ sharing in digital to analog signal conversion

A control circuit for a digital to analog signal conversion system having a local oscillator that generates four local oscillator phase signals that have a 25% duty cycle each and that are phase-shifted by 90 degrees relative to each other, a radio-frequency digital to analog converter circuit with a first plurality of switch units that generates a positive radio-frequency signal and a second plurality of switch units that generates a negative radio-frequency signal, and a power combiner circuit that generates a radio-frequency output signal based on a combination of the positive radio-frequency signal and the negative radio-frequency signal, comprising:

• a first input port that receives a baseband in-phase signal;
• a second input port that receives a baseband quadrature signal;
• a local oscillator phase signal selector circuit that is configured to generate first control signals that select for each switch unit of the first and second pluralities of switch units one of the four oscillator signals for encoding the baseband in-phase signal and another one of the four oscillator signals for encoding the baseband quadrature signal;
• and
• a voltage selector circuit that is configured to generate second control signals that select for each switch unit of the first and second pluralities of switch units to connect a single one of a first voltage, a second voltage, or ground to an output port of the respective switch unit based on the baseband in-phase signal and the baseband quadrature signal, wherein the second voltage is twice the first voltage.

A method of operating a digital to analog signal conversion system having a local oscillator, a control circuit, a radio-frequency digital to analog converter circuit with first and second pluralities of switch units, and a power combiner circuit, comprising:

• using the local oscillator to generate a plurality of local oscillator phase signals;
• receiving a baseband in-phase (I) signal and a baseband quadrature (Q) signal at the control circuit;
• generating, with the control circuit, a plurality of control signals based on the baseband in-phase signal and the baseband quadrature signal;
• receiving the local oscillator phase signals and the plurality of control signals at the radio-frequency digital to analog converter circuit;
• generating a positive radio-frequency signal of the baseband in-phase signal and the baseband quadrature signal in the first plurality of switch units and a negative radio-frequency signal of the baseband in-phase signal and the baseband quadrature signal in the second plurality of switch units by:
• selecting in first switch units of the first plurality of switch units and corresponding second switch units in the second plurality of switch units one of a first voltage, a second voltage, or ground based on at least a first control signal of the plurality of control signals,
• selecting, in the first switch units of the first plurality of switch units, two local oscillator phase signals of the local oscillator phase signals based on at least a second control signal of the plurality of control signals, and
• selecting, in the second switch units of the second plurality of switch units, two local oscillator phase signals of the local oscillator phase signals based on at least a third control signal of the plurality of control signals;
• and
• generating, with the power combiner circuit, a radio-frequency output signal based on a combination of the positive radio-frequency signal from the first plurality of switch units and the negative radio-frequency signal from the second plurality of switch units.