Lock protection type high-performance broadband microwave frequency synthesizer

Abstract

The invention discloses a lock protection type high-performance broadband microwave frequency synthesizer. The lock protection type high-performance broadband microwave frequency synthesizer comprises a constant-temperature crystal oscillator, a power divider, an analogue frequency doubling circuit, a DDS, a phase discriminator and a broadband VCO connected sequentially; the power divider is also connected to a comb spectrum generator and a broadband double-balance frequency mixer sequentially; the broadband VCO is connected to a second directional coupler, a second microwave amplifier, the broadband double-balance frequency mixer and a low-pass filter sequentially; the low-pass filter is connected to the phase discriminator, such that a closed ring is formed; the phase discriminator is connected to a second loop filter; the second loop filter is connected to the second branch of a single-pole double-throw switch; an FPGA is respectively connected with the DDS and the single-pole double-throw switch; the circuit forms a frequency synthesis circuit; and a phase-locked loop lock protection circuit is connected to the synthesis circuit. According to the invention, the DDS is used as a broadband phase-locked loop reference signal; the comb spectrum generator is used as a offset source; and thus, the frequency synthesizer, which is low in circuit complex degree, wide in frequency band, high in frequency resolution, low in phase noise and low in spurious suppression, can be realized.

Description

technical field [0001] The invention belongs to frequency synthesizers, in particular to a high-performance broadband microwave frequency synthesizer for error-proof locking. Background technique [0002] In order to realize a high-performance broadband microwave frequency synthesizer, it is necessary to adopt a variety of frequency synthesis methods to realize it. In the past, wideband microwave frequency synthesizers always made trade-offs among key indicators such as output bandwidth, frequency resolution, spurious suppression, phase noise, and circuit complexity, and it was difficult to fully consider all indicators. In addition, broadband and high-resolution frequency synthesis circuits generally require a phase-locked loop anti-error lock circuit. The traditional phase-locked loop anti-error lock circuit adopts the method of preset voltage, which is realized by using the digital-to-analog converter to output the corresponding preset voltage to the voltage control term...

AI Technical Summary

Problems solved by technology

This anti-error lock circuit has the following defects: First, because the voltage control sensitivity of the broadband VCO is very high, generally about 500MHz / V, the output frequency of the VCO is very sensitive to the tuning voltage, and the voltage-frequency characteristics between VCOs of the same type There are individual differences. Using the open-loop method of preset voltage to pull the VCO frequency has low precision and poor consistency, and sometimes it cannot even achieve the purpose of anti-error lock; secondly, the analog-to-digital converter that realizes the preset voltage output is a digital Devices, when digital devices are working, it is easy to cause interference to the phase-locked loop circuit with high electromagnetic environment requirements, affecting the spectral purity of the output signal

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