Integrated Tunable Cavity Gunn Oscillator for 60-GHz Operation in Image Line Waveguide

The design, construction, and experimental test results of a mechanically tunable Gunn oscillator using a recessed diode metal coaxial cavity coupled to an image line waveguide is described. The oscillator frequency was changed by about 10-percent by varying the bias post length into the coaxial structure. The oscillator is designed so that both the Gunn diode and resonant cavity can be quickly replaced to provide extended frequency coverage and efficiency. This Gunn diode oscillator has provided up to 15-mW CW power at 60 GHz with 10-percent tuning range.     

Characteristics of a GaN-based Gunn diode for THz signal generation

A generalized large-signal computer simulation program for a Gunn oscillator has been developed.The properties of a Gunn diode oscillator based on the widely explored GaN,are investigated using the dev...     

A 40-GHz Digital Distribution Radio with a Single Oscillator

New 40-GHs band digital radio equipment is described. In the equipment we adopted a new circuit configuration consisting of a single IMPATT diode oscillator which functions as both transmitter frequency converter and receiver load oscillator simultaneously. The principal system design factors, a unique IMPATT diode oscillator mount configuration and test results are described. The compact radio equipment is designed so that it ensures excellent cost performance for communication systems in local trunk service, even in short hop applications resulting from rainfall attenuation to the new band.     

Mixed tunneling and avalanche mechanisms in p-n junctions and their effects on microwave transit-time devices

Analytical models of dc and small-signal characteristics for Read-type diode structures are given which incorporate both tunneling and avalanche mechanisms. A "dead-space" analysis is shown to be fundamental to accurate models of thin generation regions. Pure tunneling and pure avalanche appear as the two limiting cases of the general models. In the pure tunneling limit, the diode oscillator will operate in the tunnel transit-time (TUNNETT) mode. The TUNNETT oscillator would be attractive for low-noise and medium power and efficiency applications. For diode structures which operate between the pure TUNNETT and IMPATT modes, there exists a noise performance-output power tradeoff. Computer solutions of the analytical models, for specific diode structures and operating conditions, are given, and the results are discussed and compared with experimental results whenever possible.     

Investigations on optically controlled millimeter wave Gunn oscillators

There is a growing interest in optically controlled millimeter wave oscillators. In this paper, we have investigated the external-circuit impedances of an optically controlled millimeter wave subharmonic Gunn diode oscillator, which is illuminated by GaAs/GaAlAs laser beam. The variation of the external-circuit impedances looking outward from the Gunn diode with respect to the optical injection plasma density are calculated based on a field analysis method. The results give some useful conclusions for optically controlled millimeter wave Gunn diode oscillator design. Experimentally an optical tuning frequency shift of 7MHz is achieved at W-band.     

Nonlinear Behavior and Bias Modulation of an IMPATT Diode Oscillator

Experimental results of the nonlinear behavior of an IMPATT diode oscillator under free-running and bias-modulated conditions are presented and correlated with theoretical results. Amplitude and frequency behavior of a free-running IMPATT diode oscillator such as: 1) power-frequency characteristic, 2) jump and hysteresis, 3) temperature dependence, 4) harmonic content, and 5) electronic tuning characteristics are discussed. The bias-modulation properties and their relation to the free-running behavior are described. The effects of the operating point, external Q, and injection locking on the modulation properties are presented.     

Process-Dependence of the Even-Order Nonlinearity in Anti-Parallel Diode Pair Mixers

Diode mismatch in an anti-parallel diode mixer can generate a product at the second-harmonic of the local oscillator frequency. This product is referred to as the virtual local oscillator leakage. Variability in the fabrication process results in diode mismatch and is noticeable as an asymmetry in the current-voltage characteristics. Its impact on the virtual local oscillator leakage is analyzed by studying two populations of circuits with different diode sizes, fabricated using a six inch Gallium Arsenide heterojunction bipolar transistor process. Each population contained thirty circuits, within the same quarter-wafer.      

Analysis of bias-pin resonator diode mounts for millimeter-wave oscillators

Using microstrip antenna theory and an approximate model for an IMPATT diode, a theoretical analysis is carried out to determine variation in oscillator output power with diode contact point, for a bias-pin resonator circuit. The results compare favorably with experimental values previously published and indicate that, under some conditions, oscillator power output may be increased through use of an off-center diode contact point.     

Comparison of Indirect Optical Injection-Locking Techniques of Multiple X-Band Oscillators

Experimental results of indirect optical injection-locking of two X-band FET oscillators are presented. An S-band master source is used to synchronize both oscillators simultaneously, with 18-MHz locking range using the fiber-optic link nonlinearity. The source of the optical link nonlinearity is traced to the laser diode by interferometric measurement. Both the laser diode and the FET oscillator nonlinearities can be exploited to achieve frequency multiplication of the master oscillator signal. The merits of these different methods are evaluated based on the locking range and the FM noise level of the injection-locked oscillator.     

Circuits for High-Efficiency Avalanche-Diode Oscillators

This paper describes and analyzes the circuits which have been used successfully for TRAPATT oscillator studies. The results lead to a better understanding of the TRAPATT oscillator and yield a simple model of the oscillator which is useful for circuit design. The circuit characteristics of an experimental TRAPATT oscillator are determined from measurements on the circuits and from equivalent circuit model calculations. The following conclusions can be drawn from the analysis. First, the avalanche diode requires sufficient capacitance near the diode to sustain the high-current state required for TRAPATT operation. Secondly, at a distance from the diode corresponding to approximately one half-wavelength at the TRAPATT frequency the transmission line containing the diode should be terminated by a low-pass filter. The function of the filter is to pass the TRAPATT frequency and to provide a shorting plane for the harmonics of that frequency. Finally, on the load side of the filter, tuning for the TRAPATT frequency is required. The model of the circuit described above suggests a simple explanation of the diode-circuit interaction in a TRAPATT oscillator. Simplified waveforms suggested by the model have been used to calculate power out-put, efficiency, dc voltage change, and RF impedance for the oscillator. The results agree within a few percent with those obtained for an experimental oscillator. An important conclusion of the analysis is that the high-efficiency operation of avalanche diodes at frequencies in the UHF range can be explained by the TRAPATT theory, even though the trapped-plasma or low-voltage state may last only 1/20th of the oscillation period.     

Direct optical frequency modulation and injection locking of resonant tunnel diode oscillator

Preliminary results indicate that a resonant tunnel diode (RTD) oscillator can be optically tuned, frequency modulated, and injection locked. Experiments were performed in which a 2.8 GHz RTD oscillator was frequency modulated from DC to 100 MHz and injection locked over a 150 kHz bandwidth with a laser diode via fibre optics.<>     

A Stabilized MIC Oscillator Using a Germanium Avalanche Diode (Short Papers)

A stabilized X-band oscillator using a germanium avalanche diode in a microwave integrated circuit (MIC) is proposed. The stabilization is achieved by coupling a transmission cavity to the resonant cavity in which an avalanche diode is embedded. A mode-jumping problem inherent in a coupled-cavity oscillator was solved coupling a third varactor-embedded low-Q cavity to the transmission cavity. As a result, single-mode oscillation in an MIC oscillater was successfully obtained. Varactor tuning can also be realized with as small a change in output power as 7 percent for a tuning range of 30 MHz. The experimental results and the theoretical analysis of the new stabilized oscillator are given.     

Computer simulation of Adler's generalized equation for the interaction of oscillators with injected signals

A computer simulation that solves Adler's generalized equation describing the interaction of an injected signal with a free running oscillator is presented [1]. The simulation, performed on a digital computer, offers the advantage of a fast turn-around, great flexibility, and a high degree of accuracy. In contrast to analog computer simulations, no scaling is required. The simulation is demonstrated by determining the injection locking properties of an avalanche diode oscillator and of a pulsed magnetron with injected CW signals. The results concerning avalanche diode oscillator injection locking are in good agreement with other computational methods reported in current literature. The injection locking simulation of pulsed magnetrons, the results of the simulation, appear to confirm experimental data reported in the literature.     

Calculation of external circuit impedances of mm-wave oscillator cavities by a rigorous field analysis method

This paper presents a generalized field analysis method for calculating the external circuit impedances looking outside from the active devices of some millimeter wave oscillators. For a simple oscillator model with a radial disc and a diode existing in a rectangular waveguide, the numerical results are in agreement with the experimental data. Impedance characteristics for several different oscillator configurations are given, and some useful conclusions for oscillator design are derived.     

DC instability of the series connection of tunneling diodes

An oscillator with a series connection of tunneling diodes produces significantly higher power than a single diode oscillator. However, a circuit with series-connected tunneling diodes biased simultaneously in the negative differential resistance (NDR) region of the I-V curve is dc unstable. This dc instability makes the series connection oscillator fundamentally different from a single diode oscillator. Associated with the dc instability are the phenomena of minimum oscillation amplitude and frequency. Due to the minimum oscillation amplitude, it is critical to provide the impedance match between the oscillator circuit and the series connection at the desired oscillation amplitude level. An in depth, comprehensive analysis of the dc instability is given here. Based on this analysis, a numerical procedure is developed to accurately predict the minimum oscillation amplitude and frequency. Time domain simulations which give further insight into series-connection oscillator behavior are discussed. The effect of increasing the number of diodes on the oscillator performance is explored as well. Based on numerical and simulation results, oscillators with several tunnel diodes connected in series were designed and tested. Experimental results that confirm the existence of the minimum oscillation amplitude are presented for oscillators with two, three, and four tunnel diodes     

Millimeter and submillimeter wave quasi-optical oscillator withGunn diodes

The grooved-mirror-type Fabry-Perot (GFP) oscillator was used for coherent power-combining of multiple elements in the millimeter- and submillimeter-wave region. The admittance of the Gunn diode in oscillation was measured experimentally in the millimeter-wave region to design the GFP oscillator. The gain characteristics of the diode were found at the frequencies from 42 to 48 GHz from the measured results. With this Gunn diode in the GFP resonator, oscillation was observed. The experimental results indicated that for impedance matching between the diode and the resonant cavity, the groove height must be adjusted     

新型偏置电路高稳定毫米波振荡器的研究

本文介绍了一种采用新型纵杆离心式偏置电路结构波导耿氏振荡器的设计过程和实验结果，研究结果表明，振荡器的频率稳定度可以明显提高，输出功率大，该振荡器结构简单，加工方便，成本低，抗震能力，可靠性高，具有较大的实用价值。     

The effect of operating parameters and oscillator characteristics upon the phase angle between a locked X-band Gunn oscillator and its locking signal

Experiments have been carried out to measure the phase angle between a locked negative-resistance (Gunn) oscillator and its locking oscillator. Phase angle has been measured as a function of ambient temperature, oscillator bias voltage, locking power, and the voltage applied to a varactor tuning diode coupled into the locked oscillator. Results indicate that given a knowledge of the oscillator characteristics and the operating conditions, it is possible to predict, with reasonable accuracy, the phase of the locked oscillator. The relative merits of various methods of phase control are discussed and it is concluded that the best method is to use a varactor diode coupled into the negative-resistance oscillator.     

Noise characteristics of GaAs and Si IMPATT diodes for 50-GHz range operation

Direct comparison of noise behaviors between GaAs Schottky-barrier junction and Si diffused p⁺-n junction diodes operating in the 50-GHz range is reported by using the same circuitry. In the oscillator operation, the GaAs diode exhibits excess "1/f^m" noise near carrier, whereas the Si diode shows flat spectrum. Far from the carrier, and AM-DSB-NSR of -133 dB in a 100-Hz bandwidth and an FM noise measure of 27.1 dB are observed for GaAs diodes. Corresponding values obtained for Si diodes are -125 and 36.2 dB, respectively. As a reflection amplifier, minimum noise figures of 27.5 and 38 dB are achieved for the GaAs and Si devices, respectively. These results indicate that the GaAs IMPATT is superior in noise behavior to the Si diode also in the 50-GHz frequency range by about 10 dB. It is emphasized that the noise induced in the bias circuit of the IMPATT oscillator is a replica of the sideband noise of the output power and can be used as an indicator to obtain a low-noise tuning condition of the oscillator.     

Noise effect in oscillators using multiple active devices connected in series or in parallel

The effect of noise in an IMPATT or Gunn diode oscillator on a phase or frequency fluctuation can be reduced when the oscillator is constructed of multiple diodes connected in series, compared with the oscillator using a single diode.