A novel twin-ridge-waveguide optical amplifier switch

A novel twin ridge-waveguide optical amplifier switch is reported. The technique of hydrogen passivation of acceptors has been applied to decrease the current spreading in the region between the ridges. The incorporation of a passive waveguide below the active waveguide leads to the result that using 1.53 μm TE polarized light, through and cross states, each with only 1 dB insertion loss, fiber-to-fiber, can be selected in a device of 360 μm length by varying the currents to each ridge with a total current of 140 mA. A minimum crosstalk of less than -33 dB was achieved when the cross state was selected. This is the first report of a twin ridge-waveguide amplifier switch with such a low-loss, low-polarization sensitivity, and low crosstalk     

A Novel On-Chip Amplifier for Fast I DD Current Monitoring

A novel circuit of the low-voltage application-specific amplifier is proposed and analyzed. A wide-band current amplifying cell is developed as a central part of the amplifier structure. The amplifier is designed for a built-in-current-sensor, on-chip circuitry used in high-frequency power supply current monitoring and test applications. It could be implemented with analog, digital, or mixed-signal cores in an integrated system-on-chip environment. The current amplifier has been fabricated in 0.13 and 0.18 μm CMOS technology processes with 1.2 and 1.8 V power supply, respectively. The impacts of technology scaling on amplifier's performances have been investigated as well. With sensitivity better than 500 nA, the 0.13 μm design achieves the gain-bandwidth product of 6.8 GHz, low frequency current gain of 48 dB, high linearity for the input current range of (?15 μA, 15 μA), and power consumption of 5.2 mW.     

一种新型开关电流余量放大器

提出了一种基于互补双极工艺的新型余量放大器。该余量放大器由电阻反馈阵列、开关电流阵列和互补双极运算放大器组成,采用了恒定共模电流的方式。相比于传统余量放大器,该余量放大器的时序更简单、精度更高。采用开关电流阵列来调整整个余量放大器的电流流向,采用带高增益放大器的电阻反馈阵列来产生相应的余量放大。在流水线模数转换器中,该余量放大器实现了分段放大功能。     

Effects of the collector current fall time on the class E tuned power amplifier

Presents the equations governing the operation of the amplifier when the collector current fall time during the on-to-off transition of the transistor is an appreciable fraction of the signal period. A current-source model of the transistor with a linearly decreasing collector current during the fall time is used. The following basic amplifier parameters are determined: the waveforms of the collector current, the collector-to-emitter voltage, the instantaneous power dissipated in the transistor, the optimum values of the load-network components, the output power, the power-output capability, and the collector efficiency. The decrease of the collector efficiency is e.g. 10 percent at 60/spl deg/ fall time. Experimental results are also given. The author shows the behavior of the class E amplifier at higher operating frequencies and provides more accurate circuit design procedure.     

A novel microphone preamplifier for use in hearing aids

A novel design for a microphone preamplifier for application in hearing aids is presented. The amplifier operates at a supply voltage of 1-1.3 V, the current drain is 70µA. The maximum sound level allowed is more than 105 dB SPL, with a typical noise level of 28 dB SPL. Instead of the usual voltage sensing, current sensing of the microphone is used. The amplifier consists of a fully balanced charge-to-current amplifier with no external components required. A semicustom version of the design has been integrated in a standard BIMOS process.     

Class-E amplifier with an inductive impedance inverter

A design procedure and experimental results are presented for a class-E amplifier with an inductive impedance inverter. Experimental waveforms and characteristics measured at 1 MHz with an IRF620 MOSFET are given for the amplifier, which can operate under zero-voltage switching conditions for load resistances ranging from a short circuit to an open circuit. As the load resistance is increased at a fixed frequency, (1) the output power decreases, (2) a maximum efficiency of 96% occurs for optimum operation, (3) the peak values of the transistor voltage and the transistor current decrease, (4) the normalized peak values of the transistor voltage decrease, and (5) the normalized peak values of the transistor current increase     

一种基于低压差线性稳压器的放大器设计

设计了一种静态电流约为0.6μA的运算跨导放大器电路,并已经成功地应用于一款超低静态电流的新一代低压差线性稳压器芯片中。此放大器的突出优点是与Foldback过流保护电路融合在一起,使得芯片不需要专门的限流模块,大大减少了器件与电流支路,极大地提高了电流利用率,实现了超低功耗。     

Gain stabilisation of parametric amplifiers

A method of stabilising the gain of a parametric amplifier from the pumped conduction current of a varactor diode is described. Long-term stabilities of 0.1dB/week have been achieved on a 13dB-gain amplifier with diode currents of less than 1 ?A.     

InGaP/GaAs heterojunction bipolar transistor and RF power amplifier reliability

Electrothermal stress on advanced InGaP/GaAs heterojunction bipolar transistors (HBTs) was carried out experimentally. It showed a long-term stress-induced base current instability and a decrease in the DC current gain. A class-AB RF power amplifier (PA) was also considered to study the stress effect on the amplifier’s RF performance. The SPICE Gummel–Poon (SGP) model parameters were extracted from the pre- and post-stress HBT data and used in Cadence SpectreRF simulation. The amplifier’s post-stress RF characteristics, such as the output power and power-added efficiency (PAE), remained almost unchanged even though the post-stress HBT’s DC current gain had dropped to 73.6% of its initial value.     

一种高可靠电流灵敏放大器设计

提出了一种带反馈放大器的电流灵敏放大器 ,将用于放大的 NMOS管同时作为位线多路选择器( MU X) ,与一般的电流灵敏放大器相比 ,延迟时间更短 ,而且更适于低电源电压工作。同时分析了阈值电压失配对电流灵敏放大器的影响 ,结果表明 ,失配不仅可能增大灵敏放大器时延 ,甚至造成误放大 ;带反馈放大器的电流灵敏放大器能够有效地抑制阈值失配的影响 ,其性能和可靠性良好。     

Radiation from a microstrip amplifier

A full-wave method is presented to investigate radiation from a microstrip amplifier. The spectral-domain dyadic Green's function, which takes into account both radiation and surface waves, is used to formulate an integral equation. The method of moments is then employed to find the current densities in microstrips and, subsequently, the scattering parameters of the amplifier. The radiated space and surface waves that are launched from the amplifier can be further expressed in terms of the dyadic Green's function and current densities. To verify the numerical results of scattering parameters and far-field radiation patterns, a UHF-band microstrip amplifier matching with single stubs has been implemented and measured. The comparison between simulation and measurement shows excellent agreement.     

High-current resolution broad-band SQUID amplifier suitable for TEScalorimeter

A superconducting quantum interference device (SQUID) amplifier has been developed as a current detector with both high-current resolution and broad bandwidth for a transition edge sensor calorimeter. The amplifier is a two stage SQUID (TSS) that consists of an input-SQUID with a 38-turn input coil and a 100-serial SQUID array (100-SSA) output, and has been integrated on a 3 × 3 mm Si chip using Nb thin film fabrication technology. It is designed to increase the amplifier gain and maintain matching with the parameters of the calorimeter. To avoid flux trapping in the SSA, the washer coil of the dc-SQUIDs in the SSA was made with a narrow line width of 17.5 μm. We experimentally confirmed that the designed output voltage was achieved using a one-layer p-metal magnetic shield tube in the earth's magnetic field. The performance of the shielded TSS amplifier was evaluated in liquid helium. The TSS amplifier had a gain of 10 kV/A and an impedance of 0.07 Ω at 100 kHz. When a flux locked loop circuit was used to drive the amplifier, a current resolution of 1 pA/√Hz and a rise time of 1 μs were achieved     

A low-voltage sense amplifier with two-stage operational amplifier clamping for flash memory

A low-voltage sense amplifier with reference current generator utilizing two-stage operational amplifier clamp structure for flash memory is presented in this paper, capable of operating with minimum supply voltage at 1 V. A new reference current generation circuit composed of a reference cell and a two-stage operational amplifier clamping the drain pole of the reference cell is used to generate the reference current, which avoids the threshold limitation caused by current mirror transistor in the traditional sense amplifier. A novel reference voltage generation circuit using dummy bit-line structure without pull-down current is also adopted, which not only improves the sense window enhancing read precision but also saves power consumption. The sense amplifier was implemented in a flash realized in 90 nm flash technology. Experimental results show the access time is 14.7 ns with power supply of 1.2 V and slow corner at 125 ℃.     

A high efficiency PWM CMOS class-D audio power amplifier

Based on the difference close-loop feedback technique and the difference pre-amp, a high efficiency PWM CMOS class-D audio power amplifier is proposed. A rail-to-rail PWM comparator with window function has been embedded in the class-D audio power amplifier. Design results based on the CSMC 0.5 μm CMOS process show that the max efficiency is 90%, the PSRR is -75 dB, the power supply voltage range is 2.5-5.5 V, the THD+N in 1 kHz input frequency is less than 0.20%, the quiescent current in no load is 2.8 mA, and the shutdown current is 0.5 μA. The active area of the class-D audio power amplifier is about 1.47 × 1.52 mm2. With the good performance, the class-D audio power amplifier can be applied to several audio power systems.     

A wide-band high-voltage monolithic amplifier

A monolithic amplifier capable of 80-V swing and 1.7-V/NS slew rate has been fabricated using standard integrated circuit techniques. The amplifier is intended for capacitive loads such as in electrostatic deflection applications. The totem-pole technique is combined with active feedback to produce this large voltage swing without excessive power consumption. A new output circuit linked with a floating current source is used to supply large accurate positive and negative charging currents over a large dynamic range. The amplifier voltage range is extendable by increasing the degree of stacking in the totem-pole arrangement.     

峰值电流模DC-DC转换器中多功能误差放大器电路设计

提出了一种适合于峰值电流模DC-DC转换器的新型多功能误差放大器电路.与斜坡电压信号结合可实现软启动功能,实现了从启动阶段到稳定工作状态的平滑过渡,无扰动出现,并有效地消除了启动阶段的浪涌电流和电压过冲;同时还具有最大电流限制和模式切换功能.该误差放大器集成到一款峰值电流模升压型DC-DC转换器中,电路采用CSMC 0.5μm BCD工艺实现.仿真结果表明：3.5V的输入电压下,误差放大器消耗的静态电流为4.48μA,并且能够实现软启动、最大电流限制、模式切换功能.电路具有简单易实现,功耗低的特点.     

A feedforward technique with frequency-dependent current mirrorsfor a low-voltage wideband amplifier

A feedforward technique using frequency-dependent current mirrors for a low-voltage wideband amplifier is presented. In the conventional single-stage wideband amplifiers, the folded cascode structure is used. However, the common-gate transistor requires an additional V_{DS sat} and reduces the available output voltage range. In this study the cascode structure is avoided; instead, a frequency-dependent current mirror, whose input impedance becomes higher for a higher frequency, is used to form the feedforward path from the input of the current mirror with a feedforward capacitor. This technique is effective to improve a 100 MHz-1 GHz frequency characteristic of the amplifier. The amplifier has been fabricated using the standard 0.8 μm CMOS process. The phase margin is improved from 46-66° without sacrificing the unity gain frequency of 133 MHz compared with the amplifier without this technique. The amplifier operates at 2.5 V power supply voltage and consumes 12 mW     

Large-swing CMOS buffer amplifier

A circuit configuration for a CMOS buffer amplifier is described. The circuit, which is an enhancement of a previously reported buffer amplifier, features a large output voltage swing and a well-controlled quiescent current. A buffer amplifier of this type has been implemented in a 1.5-μm CMOS technology. The prototype occupies an area of 275 mil². It works with a 5-V supply and can drive more than 4.2 V (peak to peak) in to 300 Ω with a total harmonic distortion of less than 0.025%     

超磁致伸缩伺服阀用伺服放大器的设计及分析

为驱动超磁致伸缩伺服阀,结合超磁致伸缩执行器驱动电源与伺服阀用伺服放大器的性能要求设计了超磁致伸缩伺服阀用伺服放大器,并建立了其电路模型,仿真分析了功率运算放大器的开环增益对其输出性能的影响.仿真结果表明,在功率运算放大器开环增益大于80 dB时,电路特性可满足设计要求.在驱动负载为额定值时,测试结果表明,样机的输出电流线性度为3％;输出电流2A时,其阶跃响应的调节时间小于0.5 ms,幅频宽可达2 kHz;在驱动频率小于1 kHz时,输出电流失真小且无相位滞后.     

宽带单片低噪声放大器的增益温度补偿

分析了PHEMT的增益-温度特性和漏电流-温度特性,发现PHEMT增益和漏电流都是随温度的升高而降低,并发现了一定栅宽的PHEMT在大于某一频率时,其增益受温度变化较小的原因.提出了两种自动温度补偿的方法,并分析了每种方法的温度补偿原理.串联源电阻的温度补偿可使PHEMT的漏电流基本保持不变,在一定程度上能降低温度对增益的影响.而自动栅压温度补偿则是强温度补偿,它可随温度的升高,自动提高栅极电压,提高PHEMT的跨导,从而大大减少温度对增益的影响,达到温度补偿的目的.把这两种自动温度补偿的方法结合应用到宽带低噪声放大器中,发现补偿效果良好.试验发现温度补偿后,温度从-55℃~+85℃时和-55℃~+125℃时,放大器的增益在6GHz时的降差分别减小了60%和51%,较大地改善了放大器的温度-增益性能.