Microwave Frequency More High Frequency Doubling With Low Phase Noise Source Study

Frequency synthesizers are key parts of the decision to the performance ofelectronic systems.With the development of national defense, aerospace and wirelesscommunications technology, frequency synthesizers’ performance of pase noise,spurious, resolution and frequency hopping speed is required more and more by theelectronic systems. So that high performance frequency synthesizers has become aresearch hotspot.This paper introduces the design of a microwave multi-frequencies high-ordermultiplier which is the key part of a wide band, low phase noise and low spurious highperformance frequency synthesizer, including tow parts of the L-band and C-band,downconverting frequency in the phase-locked loop circuit, to realize the wideband andultra-low phase noise. This paper first introduces several common frequency synthesizertechnologies, compares and analyses the characteristics of the various methods, andchooses and decides the system solution according to the specifications. The L-bandmultiplying frequency source is implemented by the way of extracting the amplifer’sharmonics. While the C-band frequency source is realized by comb-generator. In themultiplier circuit this paper describes the design of the comb-generator, simulates andanalyzes the various factors that affect the performance of comb-generator. In thefrequency selecting and amplifying circuits, the design of SIR filter and the way toeliminate amplifer’s self oscillation is descrbed in detail. Since these two modules areused in the PLL circuit which will filter out spurious by loop filter, so that in this paperthe spurious suppression is not the key indicator, rather than the phase noise.The test results show that the output frequencies’ power of L-band frequencymultiplying source is13dBm, power flatness is1.5dB, and the phase noise is betterthan-120dBc/Hz@10kHz. When use a100M crystal which phase noise is better than-160dBc/Hz@10kHz, the C-band frequency multiplying source’s phase noise will betterthan-120dBc/Hz@10kHz.