Patent ID: 7940859

Claim:
A transmission circuit for generating and outputting a transmission signal based on input data, the transmission circuit comprising: a signal generating section for performing predetermined signal processing on the input data, thereby generating an amplitude signal and an angle modulation signal; an offset compensation section for compensating for a magnitude of the amplitude signal in accordance with a predetermined instruction; an amplitude amplifying section for outputting a signal corresponding to the magnitude of the amplitude signal inputted via the offset compensation section; an amplitude modulation section for amplitude-modulating the angle modulation signal by using the signal outputted from the amplitude amplifying section, and outputting a resultant signal as a modulation signal having been angle-modulated and amplitude-modulated; a power measuring section for measuring an output power of the amplitude modulation section; a memory section for storing an offset compensation value for compensating for an offset characteristic of the amplitude modulation section and a gain for compensating for an offset characteristic gradient of the amplitude modulation section; and a control section for controlling, at a predetermined timing, operations of the offset compensation section and the power measuring section, wherein the offset compensation section includes an arithmetic processing section for outputting a plurality of amplitude signals whose magnitudes are varied from each other and calculating the gain in accordance with a plurality of changes in the output power of the amplitude modulation section, the power measuring section measuring the output power when the plurality of amplitude signals are outputted, in accordance with an instruction from the control section, the offset compensation section reads, from the memory section, the offset compensation value and the gain corresponding to the output power of the amplitude modulation section, the output power having been measured by the power measuring section, amplifies the amplitude signal based on the gain, and adds the read offset compensation value to the amplitude signal.