Effects of CW interference on phase-locked loop performance

This paper focuses on the modeling and analysis of phase-locked loops in the presence of continuous wave (CW) interference such that the operating vulnerability to CW jamming and interference can be accessed. The loop phase error is characterized, and the conditions under which the loop remains locked in frequency to the desired carrier are presented. Analysis is conducted for arbitrary offsets of carrier and interferer signal frequencies relative to the quiescent voltage-controlled oscillator (VCO) frequency. The results show that loop performance depends not only on the frequency difference between the desired signal and interferer, but also on the frequency offset between the quiescent VCO oscillation and desired carrier. The vulnerability of the loop to the presence of interference increases if interferer and desired signal spectral locations are in opposite sides of quiescent VCO frequency     

Current-conveyor-based single-element-controlled and current-controlled sinusoidal oscillators

A new single-element-controlled sinusoidal oscillator circuit that incorporates two second generation current conveyors (CCIIs), two grounded capacitors and two resistors is presented and analysed. The circuit is beneficial to monolithic integrated circuit implementation by the use of grounded capacitors. In addition, a new current-controlled sinusoidal oscillator using only two second generation current controlled conveyors (CCCIIs) and two grounded capacitors can be achieved by replacing CCIIs and resistors series at X terminals with CCCIIs. The oscillators provide extremely low passive ω₀-sensitivities and good frequency stability. Moreover, the oscillation frequencies of the CCII-based and the CCCII-based oscillators can be controlled, respectively, by a grounded resistor and by an external bias current. Experimental and SPICE simulation results that confirm the theoretical predictions are given.     

CW performance of vapor-grown GaAs transferred electron oscillators

The CW performance of GaAs transferred electron oscillators (TEO) is described. The TEO were fabricated from n⁺-n-n⁺epitaxial structures of GaAs grown from the vapor phase. The devices consisted of single mesas, 5-6 mil in diameter, on plated silver heat sinks. Fifteen devices were fabricated from three separate wafers and the results were very uniform. The dc to RF efficiency varied between 4 and 5.7 percent for the 15 devices packaged and tested. The best results were 350 and 390 mW of RF power with a conversion efficiency of 5.4 and 5.7 percent, respectively, at approximately 17.5 GHz from single 5.5-mil mesas. These data represent new highs in performance from single-mesa TEO at this frequency. The results indicate that vapor epitaxial growth procedures combined with a device fabrication scheme based on plated heat sink technology can yield reproducible TEO with RF powers greater than 250 mW at efficiencies greater than 5 percent. The results indicate also that the plated heat sink approach will be useful for other devices, such as IMPATTS, in which thermal considerations limit device performance.     

Direct direction measurements of noise in CW magnetrons

For some time the subject of noise generation in magnetrons has been under study in our laboratory. The unmodulated CW magnetron was chosen as the first subject for investigation, because some of the complications of pulsed or modulated tubes are thus avoided. Since any heterodyning method introduces the noise of another microwave oscillator, a method of direct detection has been employed. This method involves the use of a crystal-video receiver for both AM and FM detection.     

Noise loading performance of a phase-locked IMPATT oscillator for multichannel FM signals

Results of a noise loading test for an IMPATT oscillator which is phase-locked to an external FM driving signal [1] are discussed. Amplification (the ratio of power output of the oscillator to power input of the driving signal) of about 15 dB could be obtained for 960 telephone message channels.     

Design of active inductor-based current-controlled oscillators using gm/Id methodology

This paper presents a novel design procedure based on gm/Id methodology to achieve a trade-off between tuning range, phase noise and output swing of active-inductor-based current-controlled oscillators (CCOs). It is shown that equations for the phase noise and corner frequency of the selected CCO configuration are related to the gm/Id parameters. In accordance with the above relations, the designed CCO is simulated using 0.18 µm TSMC CMOS technology parameters. The simulation exhibits a tuning range of 432 MHz to 3.54 GHz, a phase noise in the range of −84 dBc/Hz to −104.6 dBc/Hz at 1 MHz offset from carrier and a figure of merit of 178.4 dB in 1.453 GHz.     

CW operation of a cleaved-coupled-cavity array of phase-locked GaAlAs lasers

Tunable single-longitudinal-mode operation has been obtained at power levels up to 50 mW from a continuously operating cleaved-coupled-cavity array of phase-locked diode lasers. In addition, conversion of a multilobed to a single-lobed radiation pattern was observed as a function of current supplied to the control segment of the coupled cavity.     

Large signal design of broadband monolithic microwave frequencydividers and phase-locked oscillators

This paper presents a design method for phaselocked devices such as frequency dividers or injection-locked oscillators. The method requires a full nonlinear analysis of the circuit. This analysis relies upon harmonic balance techniques and is suitable for monolithic circuits simulation. First, a modified formulation of the general harmonic balance equation is proposed which includes the presence of probes. These probes allow us to suppress the degenerated solution of the HB equation in autonomous cases. Moreover, a global stability analysis of phaselocked regimes is carried out. It provides invaluable information on the nonlinear behavior of the device. In particular, synchronization bandwidths as well as power ranges for which the circuit can be synchronized are obtained from the stability loci drawn in the parameter space. All these features have been used to design a broadband monolithic frequency divider, and the simulated and experimental results have been compared with very good accuracy. Therefore, the method proposed is a very useful tool for the design of potentially unstable circuits     

Low-noise operation of CW GaAs avalanche diode oscillators

Previous pulsed low-noise measurements of avalanche oscillators have now been extended to CW devices having GaAs vapor-grown p-n junctions. The best AM noise-to-signal ratio observed was -140 dB, which is about 15 dB better than previously measured for GaAs avalanche diode oscillators.     

Direct frequency modulation with CW Gunn and IMPATT oscillators

Demodulation of frequency-modulated signals has been carried out with frequency-locked CW Gunn and IMPATT oscillators. The process utilized the coupling between the bias current or voltage, respectively and the frequency deviation of the locked oscillator. A full characterization of this coupling is presented. An incremental model of the large-signal oscillator behavior is developed and shown to be in good agreement with the linear and nonlinear behavior of the demodulator.     

Transient dynamics of CW intracavity singly resonant opticalparametric oscillators

We study the transient dynamics of CW intracavity, singly-resonant optical parametric oscillators (ICSROs). Relaxation oscillations of the 1064-nm pump light are measured, in both the presence and absence of parametric conversion, in a periodically poled LiNbO₃ (PPLN) CW ICSRO pumped intracavity to a Nd:YVO₄ laser. The presence of parametric conversion is shown to significantly increase both the damping times and oscillation frequencies of the dynamics; at three times the parametric oscillator threshold, these take values of 200 μs and 2 MHz, respectively. Oscillation frequencies are shown to be in good agreement with theoretical values. The influence of energy diffusion and thermal lensing are analyzed to account for discrepences between measured and theoretical damping times. We discuss the implications of the dynamic behavior to the stable-power operation of CW ICSROs     

A survey of CW and pulsed Gunn oscillators by computer simulation

A computer simulation survey has been carried out on X-band CW and pulsed Gunn oscillators with a variety of contact conditions. It is shown that devices with a large cathode doping notch will have a nearly constant bias voltage-frequency product for optimum RF power generation. Such a relationship is not clear for devices with a smaller notch that is large enough to cause optimum injection of dipolar space charge. For both types of device there is an optimum ratio of transit frequency and cavity controlled frequency for optimum RF power generation. Several other detailed features of operation that cannot be explained by instantaneous-domain-formation models are dealt with, including the frequency dependence of the device conductance and capacity under conditions of optimum efficiency, and the bias current-voltage characteristics.     

Noise measurements of microwave local oscillators

A method for measuring the spectral distribution of amplitude fluctuations and frequency fluctuations in microwave oscillators is described. The method provides for evaluation of (1) amplitude fluctuations in terms of signal to noise ratio; (2) frequency fluctuations in terms of two parameters: (a) rms deviation; (b) rms rate of change of deviation. In addition, the method permits estimation of the correlation between these two noise components. Some typical results of measurements are described, and certain implications of the effects of system parameters on interpretation of these results are considered. For a specific system, two measurements are shown to be sufficient to determine the effect of frequency noise on system performance.     

Modeling of longitudinally pumped CW Ti:sapphire laser oscillators

Longitudinal pumping of CW Ti:sapphire oscillators is considered to predict the power output of such oscillators using folded, astigmatically compensated cavities. The model predicts how the oscillator performance is affected by the selection of Ti³⁺ concentration, material figure of merit, rod length, and pump and cavity mode waists. Experimental results for broadband CW oscillators pumped by CW argon ion lasers are reported, and these are shown to be in excellent agreement with theory. Nearly 30% slope efficiency is achieved with a four-mirror folded cavity and even higher efficiencies are predicted for optimized pumping     

Observation of sustained self-pulsation in CW operated flaredY-coupled laser arrays

The time evolution of the near-field radiation patterns of CW operated inphase locked flared `Y' coupled diode laser arrays has been observed with a streak camera. The arrays exhibit sustained self-pulsation at frequencies as high as 4 GHz     

Noise spectra of a CW silicon TRAPATT oscillator

Noise measurements on a double-sided silicon TRAPATT oscillator have been made and show that the noise is comparable to that of the silicon IMPATT oscillator.