Characteristics of an electrometric amplifier using a varactor diode

An analysis method of an electrometric amplifier using two pumped low-reverse-current silicon diodes is described. First, a mathematical model representing the i(v) characteristic near the zero, where the surface effects are the most important, is proposed. Then, from this general model, both input resistance and amplifier-sensitivity coefficients are calculated.     

Four-element varactor diode loaded polarisation-agile microstripantenna array

A square, varactor diode-loaded polarisation-agile microstrip patch, radiating either circular polarisation (left or right hand) or linear polarisation (in two orthogonal planes) is described. A linear array comprising four such patches has been designed. Measurements show, when operated in circular polarisation, axial ratios better than 0.5 dB and, in linear polarisation, cross-polar levels better than -20 dB     

Capacitance of a hyperabrupt tuning varactor diode

The voltage variable capacitor has been used in tuning circuits for some time. The hyperabrupt varactor diode is fabricated to yield an especially steep capacitance-voltage characteristic under reverse bias conditions. An analysis of this diode yields an analytical expression for capacitance versus applied reverse bias which agrees remarkably well with the experimentally determined C-V curves.     

1.9 GHz low loss varactor diode pre-distorter

Pre-distorters implemented at circuit level using series diodes have a high loss. The method presented here combines source/load second harmonic control with a parallel connected varactor diode. A reduction of 15 dB in the spectral regrowth at 1.9 GHz is achieved with a low loss of 2 dB due to the varactor diode     

1.6 GHz VCO with on-chip inductor and varactor diode

Using the base-emitter junctions of a bipolar transistor as a varicap diode and an on-chip spiral inductor, a fully integrated bipolar LC VCO realised in an industrial bipolar technology is presented     

基于GaAs变容二极管的电调滤波器芯片设计

介绍基于GaAs变容二极管工艺的电调滤波器芯片的研究与设计,包括变容材料制备、二极管模型建立以及电路设计。设计数款电调滤波器,工作频段范围覆盖1~19 GHz。测试结果显示,电调滤波器具有超过一个倍频程的调谐范围,器件击穿电压大于+30 V。本文选取中心频率为2~5 GHz可调的一款电调滤波器进行详细介绍,控制电压范围为0~15 V,插入损耗在10 dB左右,输入和输出驻波(电压驻波比)均优于1.8。设计的系列化电调滤波器具有一致性高、小型化、低成本和免调试等优势,拥有良好的应用前景。     

Transient response of new type of varactor diode having multilayer structure

The transient response of a new type of varactor diode consisting of a semiconductor multilayer structure has been calculated by 2-dimensional time-dependent computer simulation. The simulated results show that the transient time of such a diode is somewhat larger than that of the conventional one with the same material parameters and diode dimensions.     

Design consideration of monolithic millimeter-wave barrier varactor diode frequency multiplier arrays

A new device structure for highly efficient frequency tripling in the millimeter and submillimeter wavelength regions is presented. The Barrier-Intrinsic-N⁺ (BIN) diode structure [1,2] is modified for highly efficient millimeter- and submillimeter-wave frequency tripling device to be employed into the monolithic back-to-back diode frequency tripler array. The modified BIN diode structures have series resistances of a few ohms and cut-off frequencies in the terahertz range. The modified BIN diode structures have weaker C-V nonlinearities than the BIN diode structure does, however, the modified BIN structures have much higher intrinsic cut-off frequencies than does the BIN counterpart. The C-V nonlinearity, capacitance ratio, breakdown voltage, series resistance and cut-off frequency of this new device structure will be discussed in this paper. In addition, the calculated high-frequency performance of this device using a large-signal nonlinear circuit model will be presented in this paper. The operation and performance of the monolithic diode-grid frequency tripler arrays employing large numbers of the modified BIN diodes will also be discussed in this paper.     

Large-area varactor diode for electrically tunable, high-power UHF bandpass filter

An electronically tunable, high-power, UHF (225-400-MHz) bandpass filter which utilizes large-area, high-capacitance varactor diodes has been designed and tested. The varactor diodes with 100-V breakdown potential, uniform impurity density in the active layer and 400-pF capacitance at -8-V bias are used as the tuning elements of the filter. The diodes are fabricated from epitaxial layers grown on high-conductivity silicon substrates. The epitaxial layers include an n⁺transition layer between the substrate and n-type active layer to minimize the growth defects in the n layer which reduce the breakdown potential to a fraction of the theoretical value. Measurements in a test cavity at 151 MHz indicate a diode Q of 190 at -8-V bias. Input power levels of 1-5 W can be accommodated across the tuning range. Insertion loss varies from 4 to 7 dB and intermodulation products are suppressed 30 dB or more for two input tones of 1 W each. This filter exhibits an order-of-magnitude improvement in power-handling capability over present state-of-the-art filters.     

New type of varactor diode having strongly nonlinear C/V characteristics

Experimental studies of a new type of varactor diode consisting of a semiconductor multilayer structure have been performed. It is shown that such a varactor diode has much stronger nonlinearity in capacitance variation with applied bias voltage than does the conventional varactor, which will enable efficient generation of millimetre waves by direct frequency multiplication of high order.     

面向毫米波应用的平面肖特基二极管及其大信号模型

A GaAs-based planar Schottky varactor diode （PSVD） is successfully developed to meet the demand of millimeter-wave harmonic generation. Based on the measured S-parameter, I-V and C-V characteristics, an accurate and reliable extraction method of the millimeter-wave large signal equivalent circuit model of the PSVD is proposed and used to extract the model parameters of two PSVDs with Schottky contact areas of 160 μm2 and 49 μm2, respectively. The simulated S-parameter, I-V and C-V performances of the proposed physics-based model are in good agreement with the measured one over the frequency range from 0.1 to 40 GHz for wide operation bias range from -10 to 0.6 V for these two PSVDs. The proposed equivalent large signal circuit model of this PSVD has been proven to be reliable and can potentially be used to design microwave circuits.     

Determination of the constants of the capacitance/voltage law of a varactor diode

A graphical method is proposed for finding the constants, including the stray capacitance, of the capacitance/voltage relationship of a varactor diode.     

一种指数掺杂的砷化镓平面肖特基变容二极管的设计与制作

利用标准微电子工艺研制出了一种可以应用于微波倍频电路中的肖特基势垒变容二极管,采用平面结构的制作工艺,克服了传统制作工艺的不易集成的缺点.并且在N型层的掺杂浓度呈指数规律,使变容管的变容比高于传统的均匀掺杂结构,有利于提高倍频电路的工作频率和输出功率.采用台面隔离工艺以形成分别用于制作肖特基接触和欧姆接触的两个台面.经...     

GaAs varactor diode for u.h.f. t.v. tuners

The design and fabrication of a GaAs varactor diode for u.h.f. t.v. tuners were carried out using a GaAs double epitaxial layer. The capacitance ratio of diode. C3/C25, is 6.0 and the series resistance at 470 MHz is 0.24 ?. These characteristics are much better than those of an Si diode and well satisfy the requirements for t.v. tuners.     

W-band monolithic frequency doubler using vertical GaAs varactor diode with n/sup +/ buried layer

A W-band monolithic frequency doubler was designed and fabricated using a vertical GaAs varactor diode that has an n/sup +/ buried layer and uses a mesa isolation process. An output power of 30 mW was obtained from this chip at 93 GHz with a conversation efficiency of 12%. This is believed to be the first reported W-band monolithic varactor diode frequency doubler.<>     

A metal-oxide-semiconductor varactor

CMOS technology scaling opens up the possibility of designing variable capacitors based on a metal oxide semiconductor structure with improved tuning range and quality factor. This is due to an increase in the oxide capacitance and a reduction in the parasitic resistance. A prototype metal-oxide-semiconductor (MOS) variable capacitor of 3.1 pF nominal value has been realized in a 0.35-μm standard CMOS process. A factor two capacitance change has been achieved for a 2-V variation of the controlling voltage. The varactor Q ranges from 17 to 35, at 1.8 GHz     

Large-signal varactor measurements

A simple method of measuring the large-signal parameters of a varactor diode for parametric-amplifier and harmonic-generator applications is described. These large-signal parameters and the conventional small-signal parameters are used to calculate the performance of the diodes in an X-band parametric amplifier. The practical performance of the amplifier shows very good agreement with the large-signal parameters.     

High-sensitivity MOS varactor

A simple method of realizing high-sensitivity capacitors is proposed. The analysis of the new structure proposed and the experimental results on devices fabricated are presented.     

Millimetre-wave varactor multipliers

Results are presented of measurements on frequency doublers in the millimetre-wave region employing unencapsulated silicon varactor diodes types ZC103 and ZC70D and a gallium-arsenide/phosphor-bronze point-contact varactor.