Radio frequency synthesizer and transceiver

Abstract

The embodiment of the invention provides a radio frequency synthesizer and a transceiver. The radio frequency synthesizer comprises a phase-locked loop system and a frequency synthesizing circuit, wherein the phase-locked loop system is used for outputting a signal with a first frequency and a signal with a second frequency, and the signal with the second frequency is second receiving local oscillator; the frequency synthesizing circuit is used for synthesizing the frequencies of the signal with the first frequency and the signal with the second frequency to obtain a signal with a preset frequency y, and the preset frequency y=m*f1+ / -n*f2, wherein f1 is the first frequency, f2 is the second frequency, and m and n are not 0; and the preset frequency is the multiple of the transmitting frequency of a transceiver where the radio frequency synthesizer is located or the transmitting frequency of the transceiver. By using the technical scheme provided by the embodiment of the invention, theinterference caused by transmitting signals to a voltage-controlled oscillator in the phase-locked loop system can be avoided.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to a radio frequency synthesizer and transceiver. Background technique [0002] In the communication system, the carrier signal in the transceiver is usually generated by the radio frequency synthesizer in the transceiver, figure 1 and figure 2 The structural diagrams of radio frequency synthesizers in the prior art are shown respectively. [0003] figure 1 It shows a structure diagram of a radio frequency synthesizer provided by the prior art. The phase-locked loop outputs current pulses to the low-pass filter LPF1, and LPF1 filters out high-frequency signals in the current pulses, and outputs different control voltages to the The voltage-controlled oscillator VCO1 and the voltage-controlled oscillator VCO3, the voltage-controlled oscillator VCO3 generates a signal with a frequency of 380-430MHz under the control of the control voltage, and the buffer de-jitters the signa...

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Problems solved by technology

[0006] because figure 1 The transmission frequency is the same as the oscillation frequency of VCO3 (that is, the frequency of the output signal of VCO3), figure 2 The second harmonic of the transmission frequency is the same as the oscillation frequency of VCO3 (that is, the frequency of the output signal of VCO3), which causes the transmission signal to interfere with VCO3, making the working state of VCO3 unstable, and thus unable to provide a stable transmission local oscillator

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