The invention discloses a method for improving
phase noise through double-loop mixing, and relates to the technical field of
phase noise improvement, and the method comprises the following steps: enabling a reference
signal and the output of a controlled
voltage-controlled oscillator (VCO) to form a first phase-locked loop, namely a main loop, through a first
phase detector PD-A and a first
loop filter LF-A, and carrying out the closed-loop locking of the VCO; the output
branch of the VCO is sent to a
frequency mixer, and the output of the VCO is mixed with a reference
signal or a frequency multiplication
signal and a frequency division signal of the reference signal to obtain a
frequency mixing signal; and inputting the
frequency mixing signal into a second
phase detector PD-B and forming a second feedback path, namely an auxiliary ring, through a second
loop filter LF-B, wherein the feedback quantity of the auxiliary ring is injected into or adjusts the control end of the VCO or is injected into a phase-locked
frequency divider ILFD to realize tuning of the VCO. Through a mixing complementary double-ring structure, the balance of the
noise suppression capability of a single ring in different offset ranges is broken through,
reference noise and parasitic response introduced when the bandwidth of the
single loop is expanded are avoided, and meanwhile, the problem that only
harmonic injection or
single injection path is difficult to cover the whole spectrum is solved.