Abstract
This paper describes the design and implementation of low phase noise 10-MHz crystal oscillators [using stress compensated (SC) cut crystal resonators] which are being used as a part of the chain of a local oscillator for use in compact atomic clocks. The design considerations and phase noise measurements are presented. The design includes a low-noise transformer coupled differential amplifier, spurious resonance rejection filter, and electronically tuned phase shifter. Phase noise measurements demonstrate a performance of -122 dBc to -123 dBc/Hz at 1-Hz offsets and -148 dBc/Hz at 10-Hz offsets. The phase noise at 1-Hz offset is very similar to the phase noise produced by the low-noise version of a doubled 5-MHz BVA resonator-based oscillators (model number 8607) previously produced by Oscilloquartz. The noise floor of the oscillators presented in this paper is around -161 dBc/Hz. These designs can be used as the reference oscillator to control the timing of many modern electronics systems.
Highlights
T HE phase noise and jitter in oscillators set the ultimate performance limits in communications, navigation, radar, and precision measurement and control systems
In this paper, which is a significant extension of a paper submitted to the joint EFTF–IFCS 2007 Conference [19] and the 2017 IFCS Conference [16], we present the detailed design information for all the elements required for an ultralow phase noise 10-MHz crystal oscillator
It can be seen that the oscillator shows the excellent phase noise performance down to 1-Hz offset frequency
Summary
T HE phase noise and jitter in oscillators set the ultimate performance limits in communications, navigation, radar, and precision measurement and control systems It is, important to develop simple, accurate linear theories which highlight the underlying operating principles and to present circuit implementations based on these theories. The quoted phase noise for the low-noise version of the BVA oven-controlled crystal oscillator (OCXO) 8607 oscillators in previous data sheets at 1-Hz offset is −130 dBc at 5 MHz and −122 dBc/Hz at 10 MHz. The phase noises of the oscillators described in this paper, which use standard SC cut resonators, are very similar to the doubled 5-MHz output (+6 dB) and directly to the 10-MHz output.
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