Frequency mixing circuit and method for suppressing local oscillation leakage in frequency mixing circuit

A frequency mixing circuit, comprising:

• a 90-degree bridge to pass through an input signal to generate a first input signal and a second input signal;
• an orthogonal frequency mixer, the orthogonal frequency mixer comprises:
• a first frequency mixing circuit to mix the generated first input signal with an oscillation signal of the first frequency mixing circuit,
• a second frequency mixing circuit to mix the generated second input signal with an oscillation signal of the second frequency mixing circuit, and
• a combiner passing through mixed signals of the first and second frequency mixing circuits to generate an output signal;
• a first direct current bias circuit disposed at an intermediate frequency input port of the first frequency mixing circuit;
• a second direct current bias circuit disposed at an intermediate frequency input port of the second frequency mixing circuit;
• and
• level control circuits disposed at intermediate frequency input ports and oscillation input ports of the first and second frequency mixing circuits to make input power of the intermediate frequency input ports and input power of the oscillation input ports of the first and second frequency mixing circuits to be constants.