Second local oscillator circuit of ultra short wave receiver with low-power consumption and high phase noise index

Abstract

The invention discloses a second local oscillator circuit of an ultra short wave receiver with low-power consumption and high phase noise index, which consists of a low pass filter LPF1, a phase-locked loop, an amplifier LNA, a low pass filter LPF2 and a power divider. The phase-locked loop comprises a phase discriminator PD, a low pass filter LPF3 and a voltage controlled oscillator VCO which are all connected in to each other in sequence. One output of the voltage controlled oscillator VCO passes through the amplifier LNA and the low pass filter LPF2 in turn to connect with an input of the power divider. Another output of VCO goes through the high pass filter HPF to connect with the input end of the local oscillator signal of the phase discriminator PD. The voltage controlled oscillator VCO passes through a high pass filter HPF to connect with a local oscillation signal input end of the phase discriminator PD.The invention employs a phase-locked loop mode and positions thehigh pass filter on a feedback loop of the voltage controlled oscillator VCO, which improves the stray inhibition capability and anti-interference capability of the local oscillator circuit. By front and back filtering, the phase noise of the output signal is reduced and the output signal-to-noise ratio is improved. Furthermore, this local oscillator circuit is also characterized by a simple structure, low consumption and low cost.

Description

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Although this solution has a simple structure and low cost, it has

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