A transmitter circuit includes at least one transmitting signal processing device, a compensation device and a compensation value calibration device. The compensation device generates a first compensated input signal and a second compensated input signal by respectively processing input signals according to a first compensation value and a second compensation value. The transmitting signal processing device generates a first output signal and a second output signal by processing the first compensated input signal and the second compensated input signal. The compensation value calibration device receives the first output signal and the second output signal as a first feedback signal and a second feedback signal, respectively, and includes a digital signal processor. The digital signal processor determines a calibrated compensation value according to power of the first feedback signal and the second feedback signal at a predetermined frequency and the first compensation value and the second compensation value.