An integrated wide-band varactor-tuned Gunn oscillator

A report is made of a thin-film varactor-tuned Gunn effect oscillator in X band employing unencapsulated diodes. The Gunn device, which is an inverted mesa type, is mounted off the substrate on a copper header and this arrangement can dissipate 7 W without the Gunn device suffering thermal damage. The varactor is a beam-lead silicon p⁺nn⁺IMPATT diode connected in series with the Gunn device. A circulator is integrated with the oscillator to provide load isolation, and tuning ranges in excess of 2 GHz are reported. Good agreement exists between calculated and measured values of oscillator tuning range.     

Method of improving tuning range obtained from a varactor-tuned Gunn oscillator

The letter proposes that the technique of reactance compensation, previously applied successfully to improve the bandwidth of parametric amplifiers, can be applied to varactor-tuned oscillators, such as Gunn oscillators, with significant improvement in the electronic-tuning range.     

High-performance millimetre-wave suspended stripline Gunn VCO

A novel millimetre-wave integrated circuit Gunn voltagecontrolled oscillator (VCO) has been developed with high output power using suspended stripline. An output power of 100 to 150mW has been achieved at frequencies between 33 and 42 GHz. A varactor diode was mounted in alignment and in close proximity to the Gunn diode to achieve an electronic tuning range of 300 MHz     

Q band (38 GHz) varactor-tuned Gunn oscillators

Broadband varactor-tuned Gunn oscillators for Q band operation have been designed. One version using a reduced-height waveguide cavity has an electronic bandwidth of 1.18 GHz. Another using a coaxial cavity has a bandwidth of 3.05 GHz.     

Variable-length Gunn oscillator

By optically controlling the position of extinction of a domain in a Gunn-effect oscillator, it has been possible to measure the domain transit time and the threshold electric field as a function of active sample length. The device resistivity profile can be obtained simultaneously.     

YIG-tuned Gunn effect oscillator

A mechanical cavity of coaxial or waveguide type is generally used as a resonator of a Gunn oscillator. Reported here is the use of a resonator consisting of a ferrimagnetic sample instead of the mechanical cavity to obtain the electrically tunable Gun oscillator. The coupling between the Gunn diode and the the ferrimagnetic resonator was experimentally observed and oscillation frequency from 3.2 GHz to 2.4 GHz was obtained proportionally to the applied dc magnetic field.     

A figure of merit for a varactor-tuned microwave oscillator

This note derives a figure of merit for a varactor tuned microwave solid state oscillator. Thu figure of merit is in terms of electronic tuning range and power output normalized to the available power from the untuned oscillator. This enables the varactor which will give the required combination of thorns parameters to be specified in terms of y and f _c.

The figure of merit also shows that a varactor with a large value of the product yf _c maximizes the figure of merit.     

Gunn effect swept frequency oscillator

An X-band swept frequency oscillator using a Gunn diode and a ferrite phase shifter is described. Sweep widths of 800 MHz and sweep rates up to 400 Hz with less than 3 dB power variation have been obtained.     

New digital phase-lock system for millimetre-wave Gunn oscillatorsused in radioastronomy

A new digital phase-lock system for the frequency stabilisation of millimetre-wave Gunn oscillators is described. The phase-locked loop circuit is built around a new GaAs phase/frequency comparator type 16G044 developed by Gigabit Logic Inc. The digital loop is much simpler, is more reliable, and outperforms its classical analogue counterpart, especially in frequency-agile applications     

Ferrimagnetically tunable Gunn effect oscillator

A very wide frequency tuning (5.8 to 13.0 GHz) of the Gunn effect oscillator is described, in which the properties of the ferrimagnetic resonator sphere are used as a tuning element. The circuit employed to accomplish this tuning, the power profile, and the tuning curve are also presented.     

Broadband varactor-tuned GaAs f.e.t. oscillator

A broadband varactor-tuned GaAs f.e.t. oscillator (7.4 to 13.1 GHz) is presented, together with measured and predicted performance characteristics. The circuit uses tuning in series with both the gate and the source leads of the device to maintain optimum oscillation conditions across the band.     

An electronically tuned Gunn oscillator circuit

A novel waveguide Gunn oscillator circuit is described that permits wide-band mechanical and electronic (varactor) tuning. A feature of the circuit is that a circuit model can be devised that accurately predicts the oscillator characteristics and that, therefore, can be used to formulate a realistic oscillator design procedure.     

Millimeter-wave Gunn oscillator in series operation

The feasibility of series operation of a Gunn-diode oscillator in a millimeter-wave range is demonstrated. Oscillator output power and its dc-to-RF conversion efficiency can both be increased substantially by operating two Gunn diodes in series. Output power from two diodes in series operation is higher than twice the output power obtained from one individual diode. We report that the pulsed output power from two GaAs Gunn diodes in series operation reaches 4.4 W at a frequency of 33.2 GHz.     

Frequency-shift-keyed pulse retiming with Gunn oscillator

Step-recovery diodes are used in order to produce retiming signals for a Gunn-effect f.s.k. pulse regenerator, suitable for microwave pulse communication systems at very fast bit rates.     

Sheet Gunn oscillator and thermal considerations

CW operation of a sheet Gunn oscillator is reported. The advantages of the sheet structure for CW operation are pointed out. Also, curves for determining the temperture of the device at thresold are presented as a function of the device parameters.     

Gunn oscillator with one electrode split

Experimental results for a Gunn oscillator with one split electrode are reported. Frequency tuning and phase locking have been obtained by applying a signal between the splits of the electrode.     

Wideband tunable mm-wave Gunn oscillator design

A new method of design of mm-wave Gunn oscillators has been developed and tested. The method utilises the fact that high frequency GaAs Gunn diodes work in the harmonic mode for transmission whilst allowing tuning at the fundamental. Hardware for wide frequency coverage (30 GHz centred at about 85 GHz) is described with experimental results.     

Optoelectronic oscillator employing reciprocating optical modulator for millimetre-wave generation

An optoelectronic oscillator that employs a reciprocating optical modulator is demonstrated. By giving positive optoelectronic feedback to the modulator, the reciprocating modulation in the modulator effectively multiplies the fundamental oscillation frequency by several times. A 52.8 GHz millimetre-wave signal is generated by self-oscillation.     

Design of a new low-phase-noise millimetre-wave quadrature voltage-controlled oscillator

This paper presents a new circuit topology of millimetre-wave quadrature voltage-controlled oscillator (QVCO) using an improved Colpitts oscillator without tail bias. By employing an extra capacitance between the drain and source terminations of the transistors and optimising circuit values, a low-power and low-phase-noise (PN) oscillator is designed. For generating the output signals with 90° phase difference, a self-injection coupling network between two identical cores is used. The proposed QVCO dissipates no extra dc power for coupling, since there is no dc-path to ground for the coupled transistors and no extra noise is added to circuit. The best figure-of-merit is ?188.5, the power consumption is 14.98–15.45 mW, in a standard 180-nm CMOS technology, for 58.2 GHz center frequency from 59.3 to 59.6 GHz. The PN is ?104.86 dBc/Hz at 1-MHz offset.