Wide-range tuning of solid-state microwave oscillators

Equations are derived that give the electronic tuning range of solid-state microwave oscillators in terms of the Q factor of the tuning device and the available power output. For currently available varactors the tuning range is severely limited by the Q factor but some exchange of power output for the tuning range is possible. It is shown that series tuning is superior to shunt tuning.     

Properties of diode laser pumps for high-power solid-state lasers

Diode lasers used to pump high average power solid-state lasers typically have broad spectral width so that most of the pump light is not at the peak of the gain medium's absorption feature. However, the long absorption length in these lasers enables even weakly absorbed light to pump efficiently. The result is that high absorption efficiency and improved pump distribution uniformity are possible when using realistic pump diodes. In addition, both quantities are nearly independent of the pump center wavelength.     

Injection locking of microwave solid-state oscillators

Injection locking of microwave solid-state oscillators is discussed, based on the familiar theorem that the total impedance times the current is equal to the applied voltage. Both quasi-static and dynamic analyses of the locking range, large-signal injection, locking stability, and AM and FM noise are given, and recent experimental work is reviewed briefly. No applications of injection locking are discussed in detail.     

Injected signal characteristics of high-power avalanche diode oscillators

Efficient injection locking results and other injected signal characteristics of high-power avalanche diode oscillators are presented. An injection locking figure of merit as high as 0.145 has been obtained.     

Avalanche effects in bulk InP microwave diode oscillators

An association with current runaway of nontransit frequency oscillations in bulk InP oscillators is plausibly interpreted as an avalanche generation process.     

Magnetic frequency tuning of the microwave Gunn diode oscillator

It has been found experimentally that the oscillation frequency of a Gunn diode placed in the low-dimensional resonance system “metal pin-closely set short-circuiter” can be effectively controlled by magnetic field applied in the normal direction with respect to the waveguide wide wall.     

Electronic tuning effects in the read microwave avalanche diode

Read's theory of the negative-resistance avalanche diode has been examined in detail for the small-signal case. The space-charge wave approach has been used in the analysis leading directly to a simple equivalent circuit and a general expression for the small-signal impedance which includes the significant design and operating parameters. The theory indicates that strong tuning effects will occur through variation of the dc avalanche current. This has been verified experimentally.     

Effect of varactor Q-factor on tuning sensitivity of microwave oscillators, including reverse tuning

It is shown how the effect of resistive losses in a varactor diode can drastically affect the tuning characteristics of millimetre-wave oscillators and can even cause the oscillator to tune in the reverse direction.     

Heat-sink temperature distribution of the annular solid-state microwave diode

It is shown that the heat-sink thermal conductance for an annular diode is more than twice that of a circular diode with equal area. Moreover, the annular diode radial temperature distribution at the diode/heat-sink interface is found to be considerably more uniform.     

变容管电调微波带通滤波器

本文叙述采用梳状线结构的变容管电调微波带通滤波器的设计理论和方法。推导出梳状线带通滤波器的输入、输出耦合网络的参数条件,以补偿带通滤波器的谐振器之间电磁耦合随不同调谐频率的变化;并给出使带通滤波器的绝对带宽或通带回波损耗在调谐频率范围内变化最小时,梳状线谐振器的电长度应满足的相应条件,由此来保证电调带通滤波器在较宽的调谐频率范围内具有较高的通带回波损耗,且保持带通滤波器的响应形状和绝对带宽基本不变。此外,还讨论了由电调变容管的Q值引起的带通滤波器的通带有功损耗问题。文中给出了具体的设计公式。最后,给出了一个L波段变容管电调带通滤波器的研制实例和测试结果。     

Frequency-stable tunnel diode oscillators

From a linear analysis of a tunnel diode loaded with a transmission line, it is shown that oscillations highly stable in frequency are possible. Preliminary experimental results are in agreement with the theory. Stability on the order of one part in 10/SUP 5/ is easily attained.     

大功率激光二极管阵列光束整形技术

大功率激光二极管阵列相比于同等功率的激光器有着优越的高性能和可靠性,在军事、工业、医学、航空航天等领域有着广阔的应用前景.具体应用中,大功率激光二极管阵列的光束整形技术扮演着一个重要角色.丈中提出折反光束整形系统,把线光束整形为方形或者圆形,利用此系统把20mm线光束整形为5mm×5 mm的方形光斑,软件模拟结果证明设计方法的正确性和可行性.     

General stabilization techniques for microwave oscillators

A general stabilization technique is proposed to suppress undesired spurious oscillations in microwave oscillators. The purpose is to eliminate these oscillations while maintaining the oscillation frequency and amplitude of the originally-unstable solution. The main advantage of the technique is its wide generality of application, not restricted to low-frequency spurious oscillations. It has been tested on an unstable 18-GHz push-push oscillator that has been manufactured and measured, with very good agreement with the simulation results.     

Laser diode high-power picosecond pulses

A Finnish research group from the University of Oulu has developed a new type of laser diode structure, which allows high-power picosecond optical pulses to be obtained as a result of the direct current pumping.This is a short news story only. Visit www.three-fives.com for the latest advanced semiconductor industry news.     

Millimeter-wave pulsed IMPATT diode oscillators

Double-drift silicon IMPATT diodes were fabricated for pulse source application at 35, 94, and 140 GHz. The diodes were operated with 300 ns pulsewidth and a 1.5 percent duty cycle. All sources exhibited a change in output frequency of >1 percent throughout the duration of the pulsewidth with <1 dB peak power variation. Peak pulse output power levels of 10, 2, and 0.7 W were achieved in each of the three frequency bands, respectively.     

Photo-injection p-i-n diode switch for high-power RF switching

The high RF power-switching properties of the photo-injection p-i-n switch (PIPINS), an optically controlled RF switch, are investigated. Proper functioning of a PIPINS as a low insertion-loss RF switch requires that it operates as a photoconductor, where the photo-injected charge is much greater than the RF sweep out charge. Insertion loss using 650-mW optical power was <0.4 dB at RF (VHF-UHF) power in excess of 200 W, and devices successfully standoff 200-W incident RF power with the series isolation being determined by the device capacitance (e.g., 225 fF). PIPINS hot-switching measurements are reported for the first time, with output RF power up to 180 W at low duty cycle, rise times of 1 ps, and fall times for a series shunt switch of ≈2.5 μs. The RF power for hot switching a PIPINS is limited by a latch-on effect, which is dependent on a variety of parameters, including duty cycle and repetition period, consistent with thermally generated carriers contributing to the latch-on effect. The switching properties of PIPINS make them a candidate for high RF power applications such as reconfigurable antennas, where electromagnetic isolation of the switch and control lines are critical     

Low-loss p-i-n diode for high-power MIC phase shifter

Low-loss p-i-n diodes designed for installation in an MIC 3-bit F-band phase shifter have been fabricated from bulk-grown silicon wafers with deep-diffused contact layers. The breakdown potential of these diodes exceeds 1000 V. The p-i-n diodes have a series resistance of 0.24 Ω at a forward current of 50 mA and have aQof 800 at -40-V bias. Each diode in a 180° bit phase shifter can handle 3.5-kW peak power. The 3-bitF-band phase shifter constructed with six p-i-n diodes can sustain 5-kW peak power (50-µs pulse, 0.8-percent duty cycle). The phase shifter has an average loss of 1 dB under 50-mA forward bias and -40-V reverse bias.     

Varactor characteristics, oscillator tuning curves, and AM-FM conversion

A simple analysis relates the small-signal specification of a varactor's capacitance to an oscillator's tuning curve. The notion of an effective capacitance across the amplitude of oscillation is introduced. The analysis also explains how the varactor converts AM noise on the oscillation into FM, which is phase noise. The analysis is experimentally validated.     

Equivalent actions of high-power microwave and video pulses with different polarities on semiconductor diode structures

The energy, power, and temperature characteristics of semiconductor p-n junction structure and the structure with a Schottky barrier are simulated under the actions of a high-power microwave and video pulses with different polarities. The results of simulations are presented. The temperature fields are comparatively analyzed using the numerical model of drift-diffusion thermal approximation and the interval estimates of the energy equivalence under the actions of pulses of different types.     

Magnetic tuning of coaxial IMPATT oscillators

Frequency tuning of an IMPATT coaxial microwave oscillator, using variation of susceptibility of a 5 Oe linewidth y.i.g. sphere, is described. A deviation sensitivity of 2MHz/Oe is determined experimentally. Qualitative explanation is offered for the discrepancy between this value and the theoretically predicted sensitivity.