High-frequency signal processor and wireless communication system

A high-frequency signal processor provided with a first operation mode and a second operation mode, the high-frequency signal processor comprising:

• a test signal generating circuit that generates a test signal having a first frequency component and a second frequency component;
• a first switch that transmits a signal received as a first signal at an antenna in the first operation mode and transmits the test signal as the first signal in the second operation mode;
• a mixer circuit that includes a differential circuit capable of correcting a differential balance within a specified variable range and down-converts the first signal to a second signal having a frequency band lower than the first signal;
• a phase detection portion that extracts a third signal from the second signal in the second operation mode, the third signal having a frequency component equivalent to a difference between the first frequency component and the second frequency component, and detects a phase for the third signal;
• a control portion that changes the differential balance for the mixer circuit according to a detection result from the phase detection portion,
• wherein the mixer circuit operates in the first operation mode while the differential balance is set to a first correction value within a variable range, and
• wherein the control portion, in the second operation mode, varies the differential balance and concurrently searches for a transition point allowing a phase for the third signal to transition by approximately 180° before and after varying the differential balance within a minimum fluctuation range and supplies the mixer circuit with the first correction value, namely, the differential balance corresponding to the transition point;
• an analog-digital converter circuit provided after the mixer circuit;
• a baseband circuit that performs a specified baseband process:
• and
• a second switch that selects one out of transmitting an output from the analog-digital converter circuit to the baseband circuit and transmitting the output from the analog-digital converter circuit to the phase detection portion,
• wherein the phase detection portion receives the second signal as a digital signal via the second switch,
• wherein the test signal generating circuit includes:
• a test local signal generating circuit that generates a test local signal having a specified frequency;
• a test baseband signal generating circuit that generates a test baseband signal having a frequency equivalent to a difference between the first frequency component and the second frequency component;
• a divider circuit that divides the test baseband signal into two;
• and
• a test mixer circuit that up-coverts an output signal from the divider circuit using the test local signal, and
• wherein the phase detection portion includes:
• a digital filter circuit that extracts the third signal;
• a digital amplifier circuit that amplifies an output signal from the digital filter circuit;
• a test analog-digital converter circuit that converts the test baseband signal into a digital signal:
• and
• a phase detection circuit that detects a phase for an output signal from the digital amplifier circuit with reference to a phase for an output signal from the test analog-digital converter circuit.