Apparatus and method for producing a plurality of output signals with fixed phase relationships therebetween

A linear transmitter, comprising:

• a first information signal path including a first amplifier, a first filter, and a first upconversion mixer;
• a second information signal path including a second amplifier, a second filter, and a second upconversion mixer;
• an oscillator circuit that produces a local oscillator signal at a first frequency;
• a first quadrature generator coupled to injection signal inputs of the first upconversion mixer and the second upconversion mixer, wherein the first quadrature generator includes:
• a first frequency doubler coupled to an output of the oscillator circuit that produces a first doubled output signal at a second frequency, wherein the second frequency is twice the first frequency;
• a first delay circuit coupled to an output of the oscillator circuit that delays the local oscillator signal by an amount of time that approximately equals a delay of the first frequency doubler less a period of the first frequency divided by four;
• and
• a first signal processor, having a first input coupled to an output of the first delay circuit and a second input operably coupled to an output of the first frequency doubler, that produces first quadrature output signals at the first frequency, wherein each of the first quadrature output signals has a single, determinate phase relative to the phase of the local oscillator signal;
• a combined information signal path coupled to the first information signal path and the second information signal path, and including a summer and an amplifier;
• a first feedback signal path coupled between an output of the combined information signal path and an input to the first information signal path, and including a first down-conversion mixer;
• a second feedback signal path coupled between an output of the combined information signal path and an input to the second information signal path, and including a second down-conversion mixer;
• and
• a second quadrature generator coupled to injection signal inputs of the first down-conversion mixer and the second down-conversion mixer, wherein the second quadrature generator includes:
• a second frequency doubler operably coupled to an output of the oscillator circuit that produces a second doubled output signal at the second frequency;
• a second delay circuit operably coupled to an output of the oscillator circuit that delays the local oscillator signal by an amount of time that approximately equals a delay of the second frequency doubler less a period of the first frequency divided by four;
• and
• a second signal processor, having a first input coupled to an output of the second delay circuit and a second input operably coupled to an output of the second frequency doubler, that produces second quadrature output signals at the first frequency, wherein each of the second quadrature output signals has a single, determinate phase relative to the phase of the local oscillator signal.