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Building a Microwave Frequency Synthesizer— Part 2: Component Selection
Abstract
s discussed in the previous article, a frequency synthe- sizer can be thought of as a black box containing various components (e.g., oscillators, phase detec- tors, frequency dividers, multipliers, mixers, amplifiers, etc.), which being properly connected, translate an input reference signal to a number of output fre- quencies. The synthesizer implementation as well as its ultimate performance depends heavily on characteristics of the individual components used in the design. Although there is no set definition for the term "compo- nents" (they can be actually complex conector- ized modules), in this article we will mostly refer them as surface-mount parts, which can be placed on a printed circuit board. The char- acteristics and behavior of the main synthe- sizer parts are reviewed from the perspective of their use in practical synthesizer designs.
... í µí± flicker is the flicker noise transition frequency of the reference oscillator and determined by its output stage component. A high-Q and low flicker corner, low PN silicon bipolar TCXO is preferred [14, 15] (our TCXO flicker corner is 80 Hz [16]). LPBW controls the dynamic and noise traits of the loop as well as spur attenuation and is usually set from tens to hundreds of kHz. ...
A nontrivial phase noise analysis method is proposed for frequency synthesizer of a passive millimeter-wave synthetic aperture interferometric radiometer (SAIR) imager for concealed weapon detections on human bodies with high imaging rates. The frequency synthesizer provides local oscillator signals for both millimeter-wave front ends and intermediate frequency IQ demodulators for the SAIR system. The influence of synthesizer phase noise in different offset frequency ranges on the visibility phase errors has been systematically investigated with noise requirements drawn, and the integrated RMS phase error could represent uncorrelated phase noise effects in the most critical offset frequency range for visibility error control. An analytical phase noise simulation method is proposed to guide synthesizer design. To conclude, the phase noise effects on SAIR visibility errors have been concretized to noise design requirements, and good agreements have been observed between simulation and measurement results. The frequency synthesizer designed has been successfully in operation in BHU-2D-U system.
This paper presents X-band dual output frequency synthesizer locked to a single crystal reference with improved lock time and phase noise. Lock time is critical in certain EW and radar applications like pulse to pulse hopping etc. Phase noise manifests itself in three ways in radar systems it limits the resolution of a radar system, In a communication system it limits the sensitivity of a communication system and lastly in any digital system phase noise causes jitter.
We demonstrate regenerative divide-by-two (halver) circuits with very low phase modulation (PM) noise at input frequencies of 18.4 GHz and 39.8 GHz. The PM noise of the 18.4 to 9.2 GHz divider pair was L(10 Hz)=-134 dB below the carrier in a 1 Hz bandwidth (dBc/Hz) and L(10 MHz)=-166 dBc/Hz, and the PM noise of the 39.8 GHz to 19.9 GHz divider pair was L(10 Hz)=-122 dBc/Hz and L(10 MHz)=-167 dBc/Hz.