Microwave regenerative frequency dividers with low phase noise

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.     

Phase noise performance of analog frequency dividers

The phase noise performance obtainable using silicon and GaAs-based TTL (transistor-transistor logic) and ECL (emitter-coupled logic) logic level digital frequency dividers is discussed. Measurement of the spectral performance of two types of analog dividers is reported: a parametric divider using varactor diodes and a regenerative-type divider incorporating a double-balanced mixer in the oscillator feedback circuit. Both dividers were configured for divide-by-two operation at VHF. Evaluation indicates the regenerative divider is capable of providing much lower phase noise than conventional digital logic level devices. The regenerative divider can be successfully operated over bandwidths in excess of an octave, and the design lends itself to small (i.e. TO-8) modular package implementation. Operating frequencies are bounded only by the range of the mixer and RF amplifier utilized and, as such, should extend from HF through microwave.     

Modeling phase noise in frequency dividers

A theory for modeling noise in frequency dividers and the measurements to support the theory are presented. The most complete measurements were made on ECL (emitter-coupled logic) dividers for which the primary noise contributions were from additive output noise and sampled additive input noise. Output phase power spectral density due to the latter varies as the square of the input frequency and is inversely proportion to the output frequency. The third most significant contributor was sampled output noise. A summary of available noise data is also given.     

Conjugate regenerative dividers

We discuss a novel design of a self-starting regenerative divider that permits division by 3, 4, 5, 6... instead of the usual 2. This is accomplished by having the loop oscillate simultaneously at two harmonically related conjugate frequencies, e.g., at /spl nu//4 and 3/spl nu//4. A prototype of the divide-by-four circuit has been constructed for an input frequency of 400 MHz. This divider exhibits very low phase noise, l (1 kHz) = -162 dBc/Hz and l (100 kHz) = -170 dBc/Hz, which is approximately 9 dB lower than that of its constituent parts. Simple modifications of the feedback loop of this circuit enabled it to divide by 3, 5, and 8. Operation at higher division ratios appears feasible under certain conditions.     

Phase noise performance of microwave analog frequency dividers: application to the characterization of oscillators up to the millimeter-wave range

The phase noise performance of two different microwave analog frequency dividers is characterized and compared with the values obtained using simple theories of noise in injection-locked systems. The direct measurement of the divider noise with a low phase noise synthesizer is not accurate enough, and the residual noise technique is used. The noise levels observed using this technique, between -120 and -155 dBc/Hz at a 10 kHz offset frequency, demonstrate that this divider noise is much lower than the phase noise of most microwave free running oscillators, even if this noise is still high with respect to the residual noise of amplifiers realized with the same active devices. The down conversion of microwave sources up to 40 GHz, is proposed as an application example.     

New types of transformer frequency dividers

Conclusions The dividers described above can be made for dividing high voltages (2–3.5 kV) over a wide frequency range (20 Hz–200 kHz). The divider with its variable input resistance provides a convenient and rapid reading of the input voltage for a known output voltage and, owing to this, it can be used in thermoelectric voltage comparators.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 59–61, January, 1972.     

Transistorized regenerative frequency divider

Summary Regenerative transistorized frequency dividers have a highly-stable phase characteristic with the supply voltage and ambient temperature varying over wide ranges. The above divider is not inferior in its phase stability to highly stable tube frequency dividers.The use of transistors and miniature components makes it possible to produce economical, reliable and small frequency dividers for quartz clocks. The lower power consumption of transistorized dividers makes it possible to feed them from storage batteries of a relatively small capacity.In transistorized circuits it is advisable to use inductive phase shifters for varying the quartz-clock readings.     

采用SCFL的GaAs双模高速分频器

介绍了三种ＧａＡｓ双模高速分频器的设计,分别讨论了双模分频器的工作原理及三种电路的逻辑设计,以及基于源耦合场效应管逻辑的电路结构,并给出了三种电路的模拟结果。     

Phase noise in capacitively coupled micromechanical oscillators

Phase noise in capacitively coupled microresonator-based oscillators is investigated. A detailed analysis of noise mixing mechanisms in the resonator is presented, and the capacitive transduction is shown to be the dominant mechanism for low-frequency 1/f-noise mixing into the carrier sidebands. Thus, the capacitively coupled micromechanical resonators are expected to be more prone to the 1/f-noise aliasing than piezoelectrically coupled resonators. The analytical work is complemented with simulations, and a highly efficient and accurate simulation method for a quantitative noise analysis in closed-loop oscillator applications is presented. Measured phase noise for a microresonator-based oscillator is found to agree with the developed analytical and simulated noise models.     

Phase noise in surface-acoustic-wave filters and resonators

Measurements of the phase noise modulation imparted on UHF carriers by surface-acoustic-wave (SAW) filters and resonators have been made using an HP 3047 spectrum analyzer. Three different types of SAW phase noise were observed. One type can be explained by temperature fluctuations. It is characterized by a spectral density of phase fluctuations which decreases as 1/f(2). The predominant noise mechanism in most SAW devices has a 1/f spectral density. The source of this noise is unknown, but it appears to be associated with both acoustic propagation and transduction. In filters fabricated on lithium niobate substrates, a third noise mechanism is evidenced. This mechanism produces nonstationary noise bursts that appear to originate in the transducer region. Experiments have been carried out on substrate materials, transducer metallizations, and over acoustic path lengths. The means by which low-frequency fluctuations are mixed to the carrier frequency have been studied.     

Measurement of the instantaneous frequency instability of laser radiation by frequency noise filtration

Measurement Techniques -     

Phase noise measurements in dual-mode SC-cut crystal oscillators

This paper describes the phase-noise characteristics and the analysis model of an SC-cut dual-mode oscillator. The C mode phase-noise sideband levels of -124 dBc at 10 Hz and -154 dBc at 10 kHz have been demonstrated using a dual-mode oscillator that simultaneously excited the C and B mode of a 10-MHz, third overtone, SC-cut crystal resonator. Based on Leeson's model, a phase-noise analysis model for dual-mode oscillators has been proposed also. Actual phase-noise levels of the C mode in dual-mode oscillation corresponded well to results calculated from the proposed model.     

Short time measurement of frequency and amplitude in the presenceof noise

A method for the measurement of amplitude and frequency of sinusoidal signals in the presence of noise during a few periods is proposed. The method presented gives one the possibility to make measurement of frequency and amplitude of sinusoidal signals without noise during a very short time (less than a half period) and in the case of signals corrupted by noise (during only two periods) with sufficiently acceptable results. The theoretical basis, several measurement algorithms and selected results of computer simulation are presented. The performance is compared to that of known methods     

On the 1/f frequency noise in ultra-stable quartz oscillators

The frequency flicker of an oscillator, which appears as a 1/f3 line in the phase noise spectral density, and as a floor on the Allan deviation plot, originates from two basic phenomena, namely, (1) the 1/f phase noise turned into 1/f frequency noise via the Leeson effect, and (2) the 1/f fluctuation of the resonator natural frequency. The discussion on which is the dominant effect, thus on how to improve the stability of the oscillator, has been going on for years without giving a clear answer. This article tackles the question by analyzing the phase noise spectrum of several commercial oscillators and laboratory prototypes, and demonstrates that the fluctuation of the resonator natural frequency is the dominant effect. The investigation method starts from reverse engineering the oscillator phase noise in order to show that if the Leeson effect was dominant, the resonator merit factor Q would be too low as compared to the available technology.