Novel m.o.s. differential amplifier for sampled-data applications

A novel form of differential amplifier is reported which employs a simple, capacitive input differential circuit in place of the conventional differential pair and current source. The amplifier is especially suitable for monolithic integration in an m.o.s. technology, and generates a time-multiplexed, sampled data output signal compatible with many current signal processing techniques.     

二极管型非制冷红外探测器的前端电路设计

设计了一种二极管型非制冷红外探测器的前端电路,该电路采用Gm-C-OP积分放大器的结构,将探测器输出的微弱电压信号经跨导放大器(OTA)转化为电流信号,再经电容反馈跨阻放大器(CTIA)积分转化为电压信号输出。该OTA采用电流反馈型结构,可以获得比传统OTA更高的线性度和跨导值。输入采用差分结构,可以有效地消除环境温度及制造工艺对探测器输出信号的影响。电路采用0.35 m CMOS工艺进行设计并流片,5 V电源电压供电。Gm-C-OP积分放大器总面积0.012 6 mm2,当输入差分电压为0~5 mV时,测试结果表明:OTA跨导值与仿真结果保持一致,Gm-C-OP积分放大器可实现对动态输入差分信号到输出电压的线性转化,线性度达97%,输出范围大于2 V。     

A differential-input,differential-output current mode operational amplifier

A current operational amplifier with differential input and differential output is described. The amplifier is based on the parallel connection of a CCII+ current conveyor and a CCII? current conveyor followed by a differential output transconductance gain stage. The performance of the amplifier is analysed and experimental results obtained from an implementation using standard operational amplifiers and current mirrors realized using transistor arrays are presented and compared to the theoretical analysis. It is concluded that the static small signal open loop gain and the frequency response matches the performance of conventional voltage operational amplifiers. The input offset and bias errors and the common mode rejection are shown to be strongly dependent on the matching accuracy of the current mirrors used in the conveyors. The proposed configuration can easily be integrated into a monolithic amplifier in either CMOS or bipolar technology.     

微电容超声换能器的前端专用集成电路设计

针对微电容超声换能器(CMUT)微弱电流信号检测的要求,设计了一种用于CMUT的前端专用集成电路——运算放大器(OPA)电路。运算放大器电路采用两级放大结构,第一级采用全差分折叠-共源共栅结构,输出级采用AB类控制的轨到轨输出级,在运算放大器电路反相输入端和输出端通过一个反馈电阻实现CMUT电流信号到电压信号的转换。采用GlobalFoundries 0.18μm的标准CMOS工艺进行了仿真设计和流片,芯片尺寸为226μm×75μm。仿真结果表明,运算放大器的开环增益为62 dB,单位增益带宽为30 MHz,在3 MHz处的输入参考噪声电压为2.9μV/Hz^1/2,电路采用±3.3 V供电,静态功耗为11 mW。测试结果表明仿真与实测结果相符,该运算放大器电路能够实现CMUT微弱电流信号检测功能。     

Rail-to-rail BiCMOS operational amplifier using input signal adapters with floating outputs

An operational amplifier with rail-to-rail input and output voltage range in 0.6 μm BiCMOS technology is presented. Two simple input signal adapters with floating outputs serving as pre-stages are introduced. They are followed by a differential amplifier. The adapters translate the input signals into a floating level within the operating region of the differential amplifier, enabling rail-to-rail operation. An inverter-based simple rail-to-rail class AB output stage has been used. With a single supply of 1.5 V, the proposed rail-to-rail operational amplifier achieves 72 dB DC open-loop gain, 2.54 MHz unity-gain frequency, 62° phase margin, 2.5 V/μs slew rate, and 147 μW power consumption.     

基于集成运放的信号发生器设计与仿真

信号发生器在电子电路实验和设备检测中具有十分广泛的用途。本文介绍了一种基于LM301集成运放信号发生器的设计方法,其中信号产生电路模块由积分器和比较器构成,并利用差分放大器的差模传输特性对信号变换,从而输出三角波、方波和正弦波。最后通过Protel99对电路进行仿真,仿真结果表明所设计电路完全满足设计要求。本设计具有输...     

Prediction of Gain Expansion and Intermodulation Performance of Nonlinear Amplifiers

A mathematical model for the input‐output characteristic of an amplifier exhibiting gain expansion and weak and strong nonlinearities is presented. The model, basically a Fourier‐series function, can yield closed‐form series expressions for the amplitudes of the output components resulting from multisinusoidal input signals to the amplifier. The special case of an equal‐amplitude two‐tone input signal is considered in detail. The results show that unless the input signal can drive the amplifier into its nonlinear region, no gain expansion or minimum intermodulation performance can be achieved. For sufficiently large input amplitudes that can drive the amplifier into its nonlinear region, gain expansion and minimum intermodulation performance can be achieved. The input amplitudes at which these phenomena are observed are strongly dependent on the amplifier characteristics.     

Optical level equalisation based on gain saturation in fibreoptical parametric amplifier

Optical level equalisation operation based on gain saturation in an optical fibre parametric amplifier is reported. The signal output has been measured as a function of the signal input in a fibre parametric amplifier, with the result that the signal gain saturates as the input power increases and the output power reached a maximum value at a particular input level. Utilising this gain saturation property, optical level equalisation has been demonstrated     

Signal-to-Intermodulation Noise in Biased Limiting Amplifiers

This paper summarizes 1) harmonic signal output for a variety of class C power amplifier models and 2) other biased amplifier configurations when the input consists of an arbitrary number of carriers plus noise; it also demonstrates signal suppression and/ or enhancement in the class C amplification process for several signal sets and amplifier models, and it develops expressions for output signal-to-intermodulation noise ratio if the input consists of a large number of equal amplitude carriers. Results are given in tabular form.     

基于锁相放大器的光纤电流互感器研究

为了测试光纤电流互感器中由于Faraday效应引起的旋转量,提出了采用锁相放大器处理信号的方法,改进了传统的将交流成分与直流成分相除的方法。系统将采集信号做单端电压输入测试和差分电压输入测试,并比较了单端输入与差分输入的测试效果,定性分析了输出幅值与被测电流的关系。测试结果表明,锁相放大器输出幅值与被测电流具有线l陛关系,且差分输入较单端输入幅值大、线性度好、对外界干扰抑制性强。其成果为进一步研究基于旋光效应的光纤电流互感器的应用奠定了基础。     

On the performance of the differential cascode amplifier

Analysis is made of the differential cascode amplifier stage, an amplifier made of a differential common-emitter input pair driving a differential common-base output pair referenced to the emitter potential of the input pair. The analysis shows the differential cascode amplifier to have one or more orders of magnitude increase in common-mode input resistance and common-mode rejection ratio compared to that of a conventional differential pair. Consideration is also given to the use of junction field-effect transistors for either pair in the differential cascode stage. The frequency response of the stage is studied, and a potentially troublesome common-mode complex pole pair is identified as the one disadvantage of the differential cascode circuit.     

GaAs laser amplifiers

Experimental results are presented on the operational characteristics of GaAs laser amplifiers very closely coupled to a laser oscillator. The separation between the oscillator and the amplifier was varied from 0.2 to 2.0 microns. The amplifiers were made by lapping one end at an angle of 10 to 15 degrees. This angle is several times larger than the critical angle for confinement of radiation in GaAs lasers that is estimated from experimental data to be between 2 and 3 degrees. The measured signal gain is a decaying function of input power and approaches a value of 2 to 4 for large input signals. A maximum amplifier gain of about 150 was obtained for an input signal of 2 mW/mil junction width (corresponding to an optical flux-density of about 8 kW/cm²incident on the input side of the amplifier). At this input power level, the output fluoresence is reduced by about 50 percent and the internal oscillatory modes of the amplifier are almost completely quenched. The ratio of the oscillator output actually coupled into the amplifier to the measured output from the oscillator was estimated from gain saturation measurements. It was found to be inversely proportional to the cleaved separation between the oscillator and the amplifier and was estimated as 0.5 and 0.07 for separations of 0.2 and 2 microns, respectively. The output quantum efficiency of the laser amplifier was demonstrated to be comparable to the output quantum efficiency of a single oscillator. Tests of a new structure for a low-noise, constant-gain laser amplifier are described.     

A Differential CMOS Current-Mode Variable Gain Amplifier with Digital dB-Linear Gain Control

A novel CMOS variable gain amplifier operating on current signals with a dB-linear gain control is presented. The gain control is achieved by multiplying a digitally synthesized exponentially varying control current signal by a differential input signal in the current domain. A current amplifier at the output sets the gain to the desired level. Current-mode operation allows for a reduced supply voltage by minimizing the voltage swing at the low impedance nodes of the circuit. Multiple circuit realizations for various blocks are presented allowing for designs meeting different constraints. Experimental realization of the variable gain amplifier shows the validity of the presented approach.     

Surface-acoustic-wave frequency-to-voltage converter

A frequency-to-voltage conversion technique is described by using a surface-acoustic-wave delay line with three interdigital transducers, one for input and two for output. Two output signals have a phase difference corresponding to different delay lengths, which are detected as a frequency-to-voltage converted signal via a differential amplifier. The operational principle as a discriminator is reported together with successful experimental results. This type of frequency-to-voltage converter is valid in a number of applications where high frequency is an important consideration.     

采用输入信号适配技术的BiCMOS运放

为了满足高性能开关电源中集成运放的应用需要,设计了一种结构简单且具有轨对轨输出的运算放大器.该运放基于0.5μm BiCMOS 工艺,采用浮动输出的输入信号适配器(ISAFO),将输入信号放大至差分输入级的工作区域,从而实现了轨对轨的运行.对所设计的运放进行了仿真分析,结果表明在工作电源电压为±0.75 V、外接100 kΩ电阻的条件下,该运放的直流开环增益达到了102 dB,单位增益-带宽为6.35 MHz,相位裕度为62.5°,而功耗仅约为150 μW.所设计的运放具有很宽的共模输入范围及较高的增益,所以特别适用于开关电源的误差放大器、过流、过压和过热保护模块中.     

一种适用于传感器信号检测的斩波运算放大器

提出一种适合传感器微弱信号检测应用的全差分低噪声、低失调斩波运算放大器。采用两级折叠共源共栅运放结构,基于斩波稳定及动态元件匹配技术,通过在运放低阻节点的电流通路上添加斩波开关的设计方式,增加了运放的输入信号带宽和输出电压摆幅。芯片采用TSMC 0.18μm 1P6MCMOS工艺实现。测试结果表明,在1.8V电源电压,25kHz输入信号和300kHz斩波频率下,斩波运放输入等效失调电压小于120μV,在10Hz～1kHz之间,输入等效噪声为5nV/Hz^1/2,最高开环增益为84dB,单位增益带宽为4MHz。     

A silicon-bipolar amplifier for 10 Gbit/s with 45 dB gain

A 10 Gbit/s limiting main amplifier for use in optical transmission systems was implemented in an advanced 0.4 μm silicon-bipolar technology. The device has one differential input and two differential outputs. It is mounted and bonded on a softboard carrier for all of the following measurements. The small signal differential gain is 45 dB and the bandwidth is 9 GHz. The output voltage is limited to 400 mV_pp differential at each output. The minimum input voltage for 1.10^-9 bit error ratio at a pseudo random word of length 2²³-1 was measured to be 2.25 mV _pp. The chip area is 1.8 mm×3.1 mm. The power dissipation is 400 mW at a single supply voltage of -4 V     

一种用于生物信号采集的CMOS全差分前置跨阻放大器设计

针对生物信号微弱、变化范围大等特点设计了一种用于检测微弱电流的全差分跨阻放大器(TIA)电路结构。不同于传统电路的单端输入,该结构采用高增益的全差分两级放大器实现小信号输入及轨到轨输出。基于CSMC 0.18μm CMOS工艺,采用1.8V电源电压对设计的电路进行了仿真,仿真结果表明:TIA输入电流动态范围为100nA^10μA,最大跨阻增益达到104.38dBΩ,-3dB带宽为4MHz,等效输入噪声电流为1.26pA/Hz。对电路进行跨阻动态特性仿真表明,在输入电流为100nA时,输出电压的动态摆幅达到3.24mV,功耗仅为250μW,总谐波失真(THD)为-49.93dB。所设计的高增益、低功耗、宽输入动态范围TIA适用于生物医疗中极微小生物信号的采集,可作为模块电路集成在便携设备中。     

Nonlinear Techniques for the Improvement of Signal-to-Noise Ratio

We propose a novel circuit for noise rejection, which is composed mainly of a linear amplifier, a nonlinear amplifier, and a filter. The input signal is applied to a linear amplifier, a bandpass limiter, and an envelope detector followed by a low-pass filter. The output of the lowpass filter is multiplied by the output of the bandpass limiter. The difference between the output of the multiplier and linear amplifier is the output of the proposed circuit. It is then indicated that the proposed circuit rejects noise, of which amplitude is narrow-band relative to the desired signal or noise phase.     

Extension of the common-mode range of bipolar input stages beyondthe supply rails of operational amplifiers and comparators

When the input voltage of an operational amplifier or comparator with a bipolar input stage exceeds the range of normal operation, the polarity of the output signal reverses and the input bias current increases to excessively large values. Saturation of the input transistors restricts the sensing of differential voltages to a common-mode (CM) range roughly between the positive and the negative supply rails. Input stage configurations that not only provide solutions to prevent the signal reversal and the excessive increase of input bias current, but also provide an extension of the CM range far beyond the supply rails, while the transconductance for differential input voltages remains constant, are described. Integrated implementations of the input stages realized a CM range reaching +15 V at a single supply voltage as low as 1 V, while the input bias current was limited to 6 μA