Patent ID: 8442461

Claim:
A transmitter operable to synthesize amplitude and phase components, comprising: an amplitude-signal path along which the amplitude component is conveyed; and a phase-signal path along which the phase component is conveyed, wherein the amplitude-signal path includes a delay-calibrating unit, a digital-to-analog converter operable to respond the amplitude component and a low-pass filter supplied with an output of the digital-to-analog converter, the phase-signal path includes a phase modulator operable to convert the phase component into a radio frequency component, in an operation of delay calibration, the delay-calibrating unit receives a test input signal at an input thereof and provides the test input signal to an input of the digital-to-analog converter, in the operation of delay calibration, the delay-calibrating unit detects a delay of a test output signal coming out of an output of the low-pass filter with respect to the test input signal upon receipt of the test output signal, and in the operation of delay calibration, the delay-calibrating unit calibrates an amplitude signal delay from the input of the delay-calibrating unit to the output of the low-pass filter in the amplitude-signal path in response to the detected delay of the test output signal, whereby a deference between the amplitude signal delay in the amplitude-signal path and a phase signal delay of the phase modulator in the phase-signal path is reduced, wherein in the operation of delay calibration, the test input signal is not provided to the input of the phase modulator of the phase-signal path, the phase modulator has a phase-signal-delay-calibrating function for calibrating the phase signal delay into a predetermined value, and in the operation of delay calibration, the phase signal delay of the phase modulator is calibrated into the predetermined value by the phase-signal-delay-calibrating function, and the delay-calibrating unit calibrates the amplitude signal delay in response to the detected delay of the test output signal, so that an operation of calibrating the amplitude signal delay in the amplitude-signal path and an operation of calibrating the phase signal delay in the phase-signal path are executed in parallel, thereby reducing a difference between the amplitude signal delay and the phase signal delay.