应用于神经信号再生系统的跨导放大器

采用华润上华0.6μm标准CMOS混合信号工艺设计了一种应用于植入式神经信号再生系统的跨导放大器.该放大器采用全差分结构以获得高输出摆幅,利用源反馈技术改善线性度,并设计了共模反馈电路以稳定共模输出电压.该跨导放大器工作在5V的电源电压下,具有0.55 S的跨导增益和100 kHz的3 dB带宽,可以满足系统的需要.     

电流激励神经信号再生电路

介绍了一种电流激励神经信号再生电路,该电路由探测电路和激励电路组成。探测电路由全差分运算放大器和仪表放大器组成。全差分运算放大器从神经元上端探测并放大神经信号,仪表放大器对信号进一步放大。最后激励级的跨导放大器将电压线性的转化为电流。电路采用CSMC0.5μmCMOS工艺设计,芯片版图尺寸为0.93mm×0.60mm。芯片的仿真结果为：在±2.5V供电电压下,功耗为8.1mW,输出电流最高可达0.357mA,输出电阻为152kΩ,总谐波失真小于1.9%。     

一种高线性宽带CMOS全差分放大器

设计了一种高线性度的宽带CMOS全差分放大器,输入级采用带有电阻共模负反馈的差分电路,输出级则由推挽跨导运算放大器及其反馈环路组成.采用输入级源退化电阻及输出级负反馈技术,使得差分输出峰峰值为1 V时三阶谐波失真达到-60 dB.同时利用反馈环路中反馈电容的欠阻尼滞后补偿作用,使放大器的带宽增大了15%.测试结果表明,在0.25 μmCMOS工艺下,该放大器-3 dB带宽达到150 MHz,噪声系数小于14 dB.     

一种低电压低功耗Class-AB运算跨导放大器

提出了一种新型Class-AB全差分运算跨导放大器(OTA).该OTA基于一种结构简单的电压缓冲器,在大信号非线性工作时,能够输出不受静态偏置电流限制的瞬态电流,提高了摆率和建立速度;同时,该结构还能够增强直流增益、增益带宽积等小信号特性,适合于低功耗开关电容电路的应用.另外,该OTA结构简单,适合于低电压工作.采用0.18μm CMOS工艺进行仿真,结果表明,该OTA结构能够在1V电源电压下工作.     

基于高性能升压转换器的跨导误差放大器

在分析峰值电流模式升压转换器原理的基础上,设计了一种结构新颖,高精度高性能跨导误差放大器。提出了将具有动态电流自补偿功能的基准电压电路复用为误差放大器输入级的新方法,克服了传统外接基准电压时误差放大器易受干扰和基准电路设计复杂的缺点,提高了误差信号精度和放大器跨导。设计了输出电阻可调电路,简化了补偿网络设计。电路用0.6μmBiCMOS工艺实现,测试表明:3V输入电压,1.2MHz工作频率下,误差放大器开环电压增益57dB,跨导322μS,输入偏置电流小于50nA;升压转换器输出电压15V,输出纹波小于5mV。     

一种可编程高线性CMOSOTA的设计

采用SMIC 0.18 μm工艺,±0.9 V电源电压,提出了一种可编程高线性全对称伪差分 CMOS OTA 电路.提出的伪差 分输入级电路基于基本伪差分(PD)结构并采用 HD3 前馈技术消除三阶谐波失真,输出级采用可编程电流放大器实现.使用 Cadence 软件的 Spectre 仿真器进行电路仿真可得,Gm值三个...     

全摆幅运算放大器的设计

设计了一种全摆幅输入的运算放大器。通过恒定跨导结构实现互补输入差分对共模输入电压在轨到轨范围内对恒定跨导的控制。设计中在输出结构里使用了电流求和电路,以达到输出信号相加,实现单端输出的功能。采用Spectre进行仿真,电源电压5V时,低频增益84dB,单位增益带宽12MHz。     

线性可调全差分OTA的实现

为了解决CMOS OTA跨导增益不能线性调节的问题,本文采用AB电流镜对NMOS和PMOS差分对管实现的基本OTA进行电流偏置,从而实现了一个跨导增益可以宽幅线性调节的全差分CMOS OTA电路。提出的OTA能够通过调节外部电流Iadj实现线性调节跨导增益,其误差小于2%,外部电流Iadj的调节范围为-40 A~40 A。OTA的差分输入电压摆幅为200mVp-p,输出电流的非线性度小于1.2%。电路的性能通过PSPICE仿真得到了验证。     

一种低功耗高线性度推挽跨导放大器

采用华虹NEC 0.35um BCD工艺,设计并实现了一种可作DC-DC转换器控制芯片内部误差放大器的CMOS跨导放大器,该跨导放大器采用源极电阻跨接式负反馈技术提高跨导的线性度、采用双折叠式差分对结构实现共模输入范围轨至轨(rail-to-rail)、采用低功耗偏置推挽(push-pull)输出结构提高输出驱动负载的能力,整体电路具有结构紧凑、功耗低、线性度高等特点。仿真结果表明:在5.25V电源电压下,驱动1pf负载,直流增益可以达到68.2db,功耗708uw,100kHz下跨导的三次谐波失真HD3达到-56db。     

跨导型运算放大器NE5517应用

<正> 我们通常见到的运算放大器电路,都是围绕电压输入一电压输出的常规型运放而设计的。而另一种类型的运放也常用于很多音频处理场合中,它采用电压输入→电流输出(跨导)形式工作,增益由外接控制端控制,这种器件称作跨导型运算放大器(OTA),NE5517就是一款这样的集成电路。图1为 OTA 的电路符号和工作时     

12位100MS/s ADC中采样/保持电路的分析与设计

设计了一种高性能的采样保持(S/H)电路,在1.8V的电源电压下,其性能满足12位精度、100MS/s转换速率的ADC的要求。设计中采用了一种新型的自举采样开关,提高了S/H电路的可靠性和线性度;对于高增益大带宽的运算跨导放大器OTA的带宽设计,在分析了主运放和辅助运放在带宽和相位裕度等方面的关系的基础上,提出了新的设计方法。仿真结果表明:S/H电路的差动输出摆幅达到了2V;对于输入为49MHz的正弦波,测得其信号噪声失真比达到了82dB,满足12位ADC的要求;整个电路的功耗约为20mW。     

A highly linear bulk-driven CMOS OTA for continuous-time filters

In this paper we present a bulk-driven CMOS triode-based fully balanced operational transconductance amplifier (OTA) and its application to continuous-time filters. The proposed OTA is linearly tunable with the feature of low distortion and high output impedance. It can achieve wide input range without compromising large transconductance tuning interval. Using a 0.18 μm n-well CMOS process, we have implemented a third-order elliptic low-pass filter based on the proposed OTA. Both the simulation and measurement results are reported. The total harmonic distortion is more than −45 dB for fully differential input signals of up to 0.8 V peak–peak voltage. A dynamic range of 45 dB is obtained under the OTA noise integrated over 1 MHz.     

Bulk-tuned Gm–C filter using current cancellation

A new approach for small transconductance (Gm) OTA designs, suitable for relatively low frequency filtering applications in the range of few kHz, is proposed. Small Gm values are achieved by a current cancellation technique, and are adjustable by bulk driving the MOS transistors of the input differential amplifier. The OTA design procedure takes into account Pelgrom׳s modeling of mismatch errors. A common-mode feedback control circuit based on floating gate common-mode voltage detector that shares the filter main capacitances is also presented. Experimental results obtained with a low-pass filter with tunable cutoff frequency implemented in a 0.35 μm CMOS process to verify the effectiveness of the design procedure have shown close agreement with the theory.     

A low-transconductance OTA with improved linearity suitable for low-frequency Gm-C filters

A fully differential operational transconductance amplifier is presented in this paper with enhanced linearity and low transconductance, suitable for low-frequency Gm-C filters. This paper also proposes a new common-mode feedback scheme that presents low sensitivity to large differential voltage swings at the OTA outputs. The proposed OTA was employed in the design of a fully-integrated Gm-C low-pass filter with a cutoff frequency of 30 kHz. The Gm-C filter was fabricated in a 0.35 μm CMOS technology and presented a THD at the output less than 1% for input signals with differential amplitudes up to 3.2 V.     

OTA linearity enhancement technique for high frequency applications with IM3 below -65 dB

A technique to enhance the linearity of continuous-time operational transconductance amplifiers (OTA)-C filters working at high frequencies is proposed. Each OTA consumes 10.5 mW and the transconductance can be tuned from 70 to 160 /spl mu/A/V while the IM3 remains below -70 dB up to 50 MHz for a 1.3-V/sub pp/ differential input. For a 20-MHz low-pass second-order filter implementation, the measured IM3 with an input voltage of 1.3 V/sub pp/ is below - 65 dB. The supply voltage is 3.3 V. Experimental results of the circuit, fabricated in a standard CMOS 0.35-/spl mu/m technology, are presented.     

A Novel CMOS OTA Based on Body-Driven MOSFETs and its Applications in OTA-C Filters

The operational transconductance amplifier (OTA) is one of the most significant building-blocks in integrated continuous-time filters. Traditional OTAs suffer linearity reduction as a result of the MOSFET scaling trend. In this paper, a body-driven (BD) CMOS triode-based fully balanced OTA is proposed to achieve low distortion and linear frequency tuning. In contrast to the gate-driven based OTAs (that have the tradeoff of input and tuning range), BD-based OTAs operate under a wide input range over a large tuning interval. Common-mode (CM) feedforward and CM feedback schemes have been developed so that the CM voltage varies only 7 mV over a tuning range of 1.2 V = Vtune = 1.58 V. Using the 0.18-mum N-well CMOS process, a third-order elliptic low-pass filter is implemented with the aid of the proposed OTA. The total harmonic distortion ( is -45 dB for 0.8-V peak-peak (Vpp) fully differential input signals. A dynamic range of 45 dB is obtained with the OTA's noise integrated over 1 MHz.     

Feedforward-Regulated Cascode OTA for Gigahertz Applications

A very high-frequency operational transconductance amplifier (OTA) with a new feedforward-regulated cascode topology is demonstrated in this paper. Experimental results show a bandwidth of 10 GHz and a large transconductance of 11 mS. A theoretical analysis of the OTA is provided which is in very good agreement with the measured results. We also carry out a Monte Carlo simulation to determine the effect of transistor mismatches and process variations on the transconductance and input/output parasitic capacitances of the OTA. The linearity and intermodulation distortion properties of the OTA, which are of particular interest in microwave applications, are experimentally determined using a purpose-built single-stage amplifier. For high-frequency demonstration purposes we built a larger circuit: an inductorless microwave oscillator. The fabricated oscillator operates at 2.89 GHz and has a significantly larger output voltage swing and better power efficiency than other inductorless oscillators reported in the literature in this frequency range. It also has a very good phase noise for this type of oscillators: ${-}116$ dBc/Hz at 1-MHz offset.      

A novel CMOS operational transconductance amplifier based on a mobility compensation technique

This brief describes a new linear operational transconductance amplifier (OTA) and its application to a ninth-order Bessel filter. To improve the linearity of the OTA, we employ a mobility compensation circuit which combines the transistors operating in the triode and the subthreshold regions. The proposed technique enhances the linearity of the transconductance without loss of the input swing range. The proposed OTA shows /spl plusmn/0.5% Gm variation and the total harmonic distortion of less than - 60-dB over the input range of /spl plusmn/0.8-V. The ninth-order Bessel filter employing the proposed OTA has been implemented in a 0.35-/spl mu/m n-well CMOS process under 3.3-V supply voltage. It shows the cutoff frequency of 8 MHz and the power consumption of 65 mW.     

用于脑电信号记录的低噪声低功耗放大器

为了满足脑电信号(EEG)记录阵列的应用需求,设计了一种全差分的低噪声、低功耗放大器电路.该电路利用亚阈值区晶体管作为伪电阻,与输入电容和反馈电容形成高通通路,有效抑制了输入信号的直流失调电压,无需片外隔直电容,实现了电路的全集成.放大器中的跨导放大器(OTA)采用亚阈值晶体管进行设计,实现了较大的输出摆幅、良好的功耗和噪声性能.放大器电路采用SMIC 130 nm 1P8M混合信号工艺实现,芯片面积0.6 mm2.测试结果表明,在电源电压0.6V时,放大器可处理信号带宽为10 Hz～7 kHz,等效输入噪声的均方根值为3.976 μV,噪声有效因子为3.658,总功耗仅为2.4 μW.