Signal frequency-mixing method based on passive mixer and zero intermediate frequency receiver

Abstract

The embodiment of the invention discloses a signal frequency-mixing method based on a passive mixer, comprising the following steps: a received radio frequency signal is filtered and amplified to obtain an amplifying signal; the orthogonal difference local oscillating signal with 25 percent of duty cycle is utilized to drive the passive mixer, the amplifying signal and the orthogonal difference local oscillating signal with 25 percent of duty cycle of the passive mixer are mixed to obtain a mixed signal; in the method, the passive mixer only has one conduction branch circuit at a certain time, total current can not be split and passes through an I path or a Q path totally, thereby overcoming the technical disadvantages that the conversion gain is reduced owning to conduction of the I pathand the Q path of the mixer at orthogonal curve overlapping moment of the local oscillating signal with 50 percent of duty cycle in the prior art, and the conversion gain can be improved under the condition of the same conversion efficiency; meanwhile, the signal frequency-mixing method leads difference waveforms of the local oscillating wave form not to be overlapped, so as to weaken the effect of twinkling noise of a signal channel.

Description

technical field [0001] The invention relates to the technical field of wireless communication, more specifically, to a signal mixing method based on a passive mixer and a zero-IF receiver. Background technique [0002] A mixer is a device that mixes the signal received by the antenna with the signal generated by the local oscillator. The passive mixer in the mixer has attracted people's attention because of its low noise and high linearity, and it is the most widely used The most important thing is to install it in a zero-IF receiver to mix the radio frequency signal and the local oscillator signal of the mixer; the zero-IF receiver has a high degree of integration and low power consumption, and it is used as a receiver applications are gaining more and more attention. [0003] The signal mixing method of the existing passive mixer-based zero-IF receiver is as follows: figure 1 As shown, the received radio frequency signal is filtered and amplified by the SAW filter and lo...

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Problems solved by technology

[0005] 0° in the signal mixing method in the prior art (LO IM ) and 180°(LO IP ), 90°(LO QM ) and 270° (LO QP ) waveforms of phase quadrature and phase difference will overlap: the waveform of phase quadrature will overlap, causing the IQ two paths to be turned on simultaneously, resulting in loss of conversion gain; the waveform of phase difference will overlap overlap, which will lead to the deterioration of flicker noise; secondly, the source impedance and output impedance of the passive mixer in the prior art are small, and there is a shortcoming that the noise of the post-amplifier cannot be well suppressed

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