Harmonic rejection of signal converting device and method thereof

A signal converting device, comprising:

• a plurality of signal-mixing circuits arranged to receive an input signal and local oscillating signals having different phases, wherein each of the signal-mixing circuits is arranged to receive a different one of the local oscillator signals and being adapted to:
• apply a gain to the input signal to generate an amplified input signal, the gain being adjusted according to a relationship of harmonic rejection ratios with respect to amplitude mismatches of the signal-mixing circuits;
• and
• generate an amplitude modulated mixed signal indicative of a product of the amplified input signal and the local oscillator signal;
• and
• a combining circuit arranged to combine the amplitude modulated mixed signals generated by the signal-mixing circuits to provide an output signal.

A harmonic rejection method, comprising:

• generating a reference mixing output signal according to an input signal, a reference gain, and a reference local oscillating signal;
• generating a plurality of auxiliary mixing output signals each according to the input signal, an auxiliary gain, and an auxiliary local oscillating signal;
• combining the reference mixing output signal and the auxiliary mixing output signals to generate an output signal;
• and
• wherein at least one of the plurality of auxiliary gains is adjusted according to a gain error occurs in the step of generating at least one of the plurality of auxiliary mixing output signals to compensate phase imbalances between the reference mixing output signal and each of the auxiliary mixing output signals to reduce a power of a harmonic component in the output signal.