【作者】 胡磊；

【导师】 曾云；

【作者基本信息】 湖南大学 ， 微电子学与固体电子学， 2008， 硕士

【摘要】 本文概述了电流反馈型运算放大器(CFOA)的发展历史,现状和趋势。阐述了CMOS集成电流反馈型运算放大器的优势和特点,对CMOS工艺下的金属场效应晶体管(MOSFET)的影响因素进行了分析,指出CMOS工艺下的MOSFET相比衬底PNP型BJT的CFOA更容易集成在CMOS电路中。详细的分析了CFOA的结构、原理以及电流反馈型运放相对于电压反馈型运放的优点,即与增益无关的带宽和无限大的转换速率,并分析CFOA的二级效应对整个电路的影响。设计确定了各子电路从而得到了最终的整体电路。通过大量文献中对CFOA的分析,得知电路中的两个缓冲器是整个电路的核心器件。采用一种结构新颖的缓冲器结构,很好的消除了CFOA在正向输入端和反向输入端的静态电压差;采用甲乙类的输入结构和推挽式的输出结构,有利于电路在低压低功耗的环境下工作;使用有源电流镜结构,降低了偏置电压,并大大的节省了整个芯片所占的面积。与相关文献相比,在工艺相同的情况下此电路具有更高的精度。采用0.6μm工艺模型利用HSPICE进行仿真,电路由正负1.5V直流电压提供偏置,Cc=5pf ;Rc=50kΩ;Cout=1pf。整个电路功耗为2.26mW,输入电阻约为4.5kΩ,相位裕度为53.5度,缓冲器补偿电压误差为3mV,带宽为5MHz,CMRR和PSRR+分别为27dB和11dB,开环增益为100dB。基于本文中的CFOA设计了一种应用在CMOS图象传感器中的ADC,电路仿真表明相对与类似结构的电压反馈型运放来说电流反馈型运放提高了ADC的速度,增加了电路的带宽,也降低了功耗。证明它可以广泛应用于低电压、低功耗、高速和高频电路中。基于CFOA设计了乘法器和除法器等基本的运算电路,并将其应用到积分器、滤波器和振荡器中。更多还原

【Abstract】 The developing history, present situation and trends of Current-feedback Operational Amplifier (CFOA)was summarized in this paper. The dominance and properties of the CMOS integrated CFOA were also described.The influencing factor of subthreshold MOSFET based on CMOS process were analyzed ,and pointed out that the MOSFET based on CMOS process was easier to be integrated in CMOS circuit than BJT transistors. Detailedly narrate the structure, theory of CFOA,and its abstract virtue against Voltage-feedback Operational Amplifier(VFOA),namely the frequent-independent bandgap and infinite Slew Rate.Analyzed the second-order effects.Design CMOS sub-circuits and thus the whole structure.Through analysis of lots of literature related to CFOA,the two buffers are the key cell in the CFOA structure.In this paper,we proposed a brand-new buffer that eliminates the voltage gap between positive and negative input of the amplifier in static condition;besides,we adopted rail-to-rail input and push-pull output structure,both of them were perfect choice of low power and low voltage enviroment;the active current mirror which decrease the operating voltage and area of the whole circuit was also used in the structure.Compared with CFOA that proposed in previous literature,this circuit possess higher SNR and precision,lower power dissipation.We simulated the CFOA circuit with simulation tool of Hspice, applyed 0.6μmCMOS process parameters(low Vth): its negative and positive supply were -1.5V and +1.5V respectively, Cc=5pf; Rc=50kOhm; Cout=1pf. Its power consumption was 2.262mW; and its input resistor was 4.5k Ohm, phase degree was 53.5o , the disparity between the two inputs was 3 mV, the bandgap was 5MhZ, open-loop gain was 100dB, and its CMRR and PSRR+ are 27dB and 11dB respectively.We designed an Analog-to-Digital Converter(for CMOS Image Sensor)based on CFOA,observed from simulation the ADC based on CFOA possessed a higher speed,broader bandgap against its counterparts based on VFOA.It also showed that this circuit adopted to low voltage, low power, high speed,high frequency circuits.Based on CFOA,we proposed operational circuits,such as multiplier and dividor;integrator;filter; oscillator.更多还原