A new technique for RF measurements using superconductors

The quantization of magnetic flux in a superconducting circuit can serve for the measurement of electrical quantities in the same way that we use the wavelength of light to measure length. We report a demonstration of this function in the measurement of attenuation ratio at a frequency of 30 MHz.     

一种快速测量晶体管共射极直流放大倍数(HFE)的方法

晶体管是一种常用的半导体分立器件,共射极直流放大倍数(HFE)是其重要的一个参数,定义为指定集电极和发射极之间的电压(Uce)下、指定集电极电流(Ic)时和基极电流(Ib)的比值.晶体管是电流控制型器件,为达到指定Ic,在测量时通常采用扫描法:逐步增加Ib,测量Ic的值,当到达指定值时停止扫描,计算比值.这种方法效率很低,本文介绍了一种快速测试的方法,借助ATE上参数测量单元(PMU)的加流功能,一次就可以快速测量出放大倍数.     

Analysis of DC and analog/RF performance on Cyl-GAA-TFET using distinct device geometry

In this paper, analysis of DC and analog/RF performance on cylindrical gate-all-around tunnel field-effect transistor (TFET) has been made using distinct device geometry. Firstly, performance parameters of GAA-TFET are analyzed in terms of drain current, gate capacitances, transconductance, source-drain conductance at different radii and channel length. Furthermore, we also produce the geometrical analysis towards the optimized investigation of radio frequency parameters like cut-off frequency, maximum oscillation frequency and gain bandwidth product using a 3D technology computer-aided design ATLAS. Due to band-to-band tunneling based current mechanism unlike MOSFET, gate-bias dependence values as primary parameters of TFET differ. We also analyze that the maximum current occurs when radii of Si is around 8 nm due to high gate controllability over channel with reduced fringing effects and also there is no change in the current of TFET on varying its length from 100 to 40 nm. However current starts to increase when channel length is further reduced for 40 to 30 nm. Both of these trades-offs affect the RF performance of the device.     

DC and RF performance of GaAs MESFET fabricated on silicon substrate using epitaxial lift-off technique

GaAs MESFETs have been fabricated on a silicon substrate using a molecular beam epitaxy grown film detached from its growth substrate and attached on a silicon substrate covered with a dielectric. The device processing is done on the silicon substrate. The MESFETs exhibit I/sub DSS/=130 mA/mm, g/sub m/=135 mS/mm and for 1.3 mu m gate length unity current gain cut-off frequency f/sub T/ of 12 GHz. Excellent device isolation with subpicoampere leakage currents is obtained.<>     

Highly linear and low noise 2.4 GHz RF front-end circuits using transformer and vertical NPN BJT

The proposed RF front-end circuits consist of a low noise amplifier using an on-chip transformer and a downconversion mixer using a parasitic vertical bipolar junction transistor and have been implemented in 0.18 mum deep n-well CMOS process. A gain of 33 dB, an IIP3 of -12 dBm, and a DSB noise figure of 4.5 dB have been achieved while consuming 5 mW from a 1.8 V supply     

射频集成电路的模拟技术

电路模拟是目前RF IC(射频集成电路)设计中主要的CAD工具，文章介绍了RF IC模拟的现状。首先简要叙述了电路稳态响应分析的试射法和谐波平衡法，这是RF IC模拟的基础技术。然后重点介绍了近年来出现的RF IC模拟中的一些新方法，包括基于Krylov子空间迭代的快速算法，包络法，多变量偏微分方程法等，指出了它们的各自的特点和适用的条件，最后讨论了今后的工作方向。     

Method to extract MOSFET substrate resistance using DC data of base resistance in parasitic BJT

A new DC method is proposed to extract the substrate resistance in MOSFETs by using current-dependent base resistance of parasitic lateral bipolar junction transistor without a complex RF extraction method. The extracted substrate resistance values using the new method match well with those using the RF one, verifying the accuracy of the new method.     

基于有源镇流改善射频功率管的热稳定性

提出一种基于有源电路的基极镇流方案,用以解决射频功率晶体管的电流集中和热稳定性问题.采用传感器检测非均匀结温分布,后级相邻触发电路触发功率器件子单元基极和发射极之间的镇流MOS管,通过分流来缓解电流集中,进而完成器件子单元的过温保护.模拟结果表明,该方案可以有效地实现对功率器件的保护,与传统的无源镇流电阻方法相比,改进后的器件具有更优良的增益特性.单个有源镇流电路仅消耗功率6.5 mW,占用面积为2 530 μm2.     

应用于无线传感器网络的射频发射机电路

设计了符合工业无线传感器网络WIA-PA标准的发射机电路.采用中频转换电路控制模拟中频信号的偏置及幅度以满足混频器的输入范围.采用正交双平衡混频器结构进行上变频,通过在固定电容上串联可调电容,拓宽了混频器的选频范围.后级接可编程功率预放大器,产生差分的功率输出信号,以满足不同传输距离的要求.发射机电路在0.13 μm CMOS工艺下进行流片.通过与WIA-PA基带芯片联合调试,测试结果表明,设计的直接上变频发射机芯片的误差矢量幅度(EVM)小于13.5％,镜像抑制达到34 dBc,很好地满足了无线传感器网络节点的应用需求.     

First-order PMD monitoring for NRZ data using RF clock regeneration techniques

We propose and demonstrate two novel techniques for 10 Gb/s polarization-mode-dispersion (PMD) monitoring for NRZ signals that use a regenerated RF clock tone as a monitoring signal. Our techniques regenerate the RF clock tone that is usually absent after square-law detection in the electrical NRZ data spectrum (in the absence of dispersion). Our first technique uses a dispersive element in the monitoring tap-line to put the beat terms between the optical clock sidebands and the carrier in phase and thus regenerates the RF clock tone after detection. Our second technique involves the use of an optical filter that is centered at the bit rate frequency on either the upper or lower sideband of the optical spectrum, removing one of the sidebands and thus preventing the beating that normally cancels the RF clock tone. We show (theoretically, via simulation, and experimentally) the effect that PMD has on these regenerated RF clock tones. We also demonstrate PMD compensation at 10 Gb/s using these techniques for monitoring and show a 6-dB improvement in the 1% power penalty tail. Our techniques are simple, do not require modification at the transmitter, and can be applied to WDM systems via the use of a multichannel dispersive element or a tunable filter swept across all channels.     

模电教学中BJT与MOS的近似性分析

BJT 与MOS器件及电路是模电重要内容;教学中二者的电路模型与分析方法不一致,学生困惑于两套不同的器件及电路知识。本文在遵循器件及电路工作原理的基础上,首次将二者在小信号模型、电路参数、I-V方程、特性曲线、工作区间、指标计算上进行完整的近似性分析及一致性推导;在二者电路计算中,用三种单管单级放大器实例,阐述近似分析方法的便利性。本文是模电教学的有力补充。     

RF detector for on-chip amplitude measurements

A novel on-chip amplitude detector that allows for efficient debugging of complex RF circuits is proposed. The simplicity, low power consumption, flat frequency response, minimal loading of the tested circuit and possibility of multiplexing makes this detector suitable for on-chip RF amplitude measurements. Simulations and measurements confirm the detector operation.     

DC SQUID RF amplifiers

The noise and signal parameters of several types of RF amplifiers based on different SQUIDs with integrated and hybrid input coils were studied. A new type of multiloop DC SQUID with an integrated input coil and extremely low stray capacitances was designed. The inductance of a four-loop SQUID was 100 pH, the input coil inductance 1.3 nH, and mutual inductance 300 pH. The tuned integrated four-loop amplifier at 420 MHz had a noise temperature lower 0.5 K and a power gain of nearly 20 dB in a 60-MHz bandwidth. For the noise calibration of such amplifiers, SIS junctions were used as a shot noise source, or a cooled attenuator and a room temperature semiconductor noise source were used     

An investigation of the DC and RF performance of InP DHBTs transferred to RF CMOS wafer substrate

This paper investigated the DC and RF performance of the InP double heterojunction bipolar transistors (DHBTs) transferred to RF CMOS wafer substrate.The measurement results show that the maximum values of the DC current gain of a substrate transferred device had one emitter finger,of 0.8μm in width and 5μm in length,are changed unobviously,while the cut-off frequency and the maximum oscillation frequency are decreased from 220 to 171 GHz and from 204 to 154 GHz,respectively.In order to have a detailed insight on the degradation of the RF performance,small-signal models for the InP DHBT before and after substrate transferred are presented and comparably extracted.The extracted results show that the degradation of the RF performance of the device transferred to RF CMOS wafer substrate are mainly caused by the additional introduced substrate parasitics and the increase of the capacitive parasitics induced by the substrate transfer process itself.     

DC and RF performance of 0.25 μm p-type SiGe MODFET

The DC and RF performance of a 0.25 μm gate-length p-type SiGe modulation-doped field-effect transistor (MODFET) is reported. The hole channel consists of compressively strained Si_0.3Ge_0.7 layer grown on a relaxed Si_0.7Ge_0.3 buffer on a Si substrate. The combination of high-hole mobility, low-gate leakage current, and improved ohmic contact metallization results in an enhancement of the DC and RF performance. A maximum extrinsic transconductance (g(m_ext)) of 230 mS/mm was measured. A unity current gain cut-off frequency (fT) of 24 GHz and a maximum frequency of oscillation (f_max) of 37 GHz were obtained for these devices     

一种应用于DC/DC转换器的自举电路设计

设计了一种适用于DC/DC转换器的自举升压电路.采用该电路可将功率PMOS管替换为NMOS管.在相同尺寸条件下,NMOS管具有较小的导通电阻,从而提高DC/DC转换器的效率.电路基于华宏NEC的0.35 μm BCD工艺,利用Cadence中的Spectre进行了验证.并给出了该自举电路的设计思想、电路的工作原理,以及自举电容最小值的计算.当电源电压降至1.4 V,电路仍能保持正常工作.当自举电容为10 nF,电源电压为5 V,工作频率可高达2 MHz.     

小功率BJT管脚管型自动判别电路设计

本设计采用单片机AT89C2051作为中心控制单元,设计出了自动判别三极管管脚、类型的电路。该电路能迅速自动识别常见中小功率三极管的管型和管脚,并由相应的指示电路显示出判断结果。电路相对较简单,测试方便、快捷,测试结果准确,造价较低,功能扩展性强,升级方便。     

单板射频及射频/数字混合电路设计探讨

从工程应用角度,探讨了设计单板射频电路及射频数字混合PCB时需要注意的微波效应、布局、接地、滤波等信号传输和电磁兼容方面的问题,详细介绍了谐振器、耦合器、电容、印制天线、滤波器等各种印制微波效应,并有针对性地提出一些实用化的建议;同时,给出大量设计示例,供单板射频及射频数字混合PCB设计人员参考.     

Uncertainty charts for RF and microwave measurements

The scope of the calibration services for electrical quantities in the range of frequency from 0 to 100 GHz that are available from the National Bureau of Standards is discussed briefly in a historical context. Some plans for improved services that will be available in the near future are noted. Charts showing the variation of uncertainty with magnitude over the full range of the respective calibration services are presented.     

A digitally controlled DC/DC converter for an RF power amplifier

This paper describes design and implementation of a digitally controlled dc/dc converter that provides a dynamically adjustable supply voltage for a radio frequency power amplifier (RFPA). The techniques employed in the design include a combination of constant-frequency continuous conduction mode (CCM) and a variable-frequency discontinuous conduction mode to achieve very high converter efficiency over a wide range of output power levels. The variable-frequency converter control is accomplished using a current-estimator circuit, which eliminates the need for current sensing. A field-programmable gate array (FPGA)-based digital controller implementation allows programmability of the mode transition and other controller parameters. In the complete experimental system, which consists of the digitally controlled dc/dc converter and a class-E RFPA operating at 10GHz, experimental results show that the overall system efficiency is significantly improved over a wide range of RFPA output power levels.