Multipath recycling method for transconductance enhancement of folded cascade amplifier

A multipath recycling method to enhance transconductance of the folded cascode amplifier is presented in this paper. The proposed method utilizes two idle paths to conduct small signal current, which leads to significant enhancement of transconductance compared to conventional folded cascade structure. Moreover, the improved performance is almost at no expense of power dissipation. The proposed multipath recycling and the conventional amplifiers are all designed in UMC 0.18 μm CMOS technology. Simulation results demonstrate that the transconductance of the proposed amplifier is improved by 450% and dc gain enhances 16 dB when compared with the folded cascode counterpart.     

A transconductance enhanced recycling structure for folded cascode amplifier

This letter is to present a transconductance enhanced recycling structure for folded cascode amplifier. The proposed structure introduces a positive feedback path to achieve a significant boost in transconductance without increasing power or area consumption. A folded cascode amplifier using the proposed structure was implemented in SMIC standard 65 nm CMOS process. Simulation results show that the proposed amplifier achieves 400% improvement in gain-bandwidth and 16.6 dB boost in DC gain compared to the conventional folded cascode.     

A power-efficient improved recycling folded cascode amplifier

An improved recycling folded cascode amplifier for wide-bandwidth ΣΔ modulator is presented in this article. The proposed amplifier introduces internal positive-feedback pairs to achieve a significant boost in transconductance and DC gain without increasing power or area budget. The proposed recycling folded cascode amplifier was implemented in SMIC standard 65?nm CMOS process. Compared to other recycling folded cascode structures, simulation results show that the proposed amplifier achieves the enhancement of gain-bandwidth and DC gain with the best figure-of-merits.     

Double recycling technique for folded-cascode OTA

Presented is a double-recycling folded cascode (DRFC) operational transconductance amplifier (OTA), demonstrating another phase of significant performance enhancement over the existing folded cascode, recycling folded cascode and improved recycling folded cascode counterparts. Theoretical treatments and computer simulations under the same 65 nm CMOS technology justify fairly the merits of the proposed DRFC OTA.     

A very high-frequency CMOS complementary folded cascode amplifier

A wide-band, fast settling CMOS complementary folded cascode (CFC) transconductance amplifier for use in analog VLSI high frequency signal processing applications is introduced. The superior performance of the CFC architecture over that of the folder cascode (FC) or mirrored cascode (MC) approaches for VLSI amplifiers is demonstrated. The symmetrically configured complementary input stage provides a wide common-mode input voltage range. The amplifier performs as an operational transconductance amplifier (OTA) and displays a first-order dominant pole when loaded by a shunt capacitor. The transconductance amplifier is small in area (0.016 mm²), and well suited for high frequency analog signal processing applications. Simulation and experimental results demonstrate a DC gain of approximately 50 dB, with a 0.1% settling response of under 10 ns for loads varied from 0 to 2 pF     

Adaptive double recycling folded cascode amplifier

Analog Integrated Circuits and Signal Processing - A new structure for improving the performance of recycling folded cascode (RFC) operational transconductance amplifier (OTA) is presented. The...     

Novel low-voltage ultra-low-power DVCC based on floating-gate folded cascode OTA

In this paper a novel low-voltage ultra-low-power differential voltage current conveyor (DVCC) based on folded cascode operational transconductance amplifier OTA with only one differential pairs floating-gate MOS transistor (FG-MOST) is presented. The main features of the proposed conveyor are: design simplicity; rail-to-rail input voltage swing capability at a low supply voltage of ±0.5 V; and ultra-low-power consumption of mere 10 μW. Thanks to these features, the proposed circuit could be successfully employed in a wide range of low-voltage ultra-low-power analog signal processing applications. Implementation of new multifunction frequency filter based on the proposed FG-DVCC is presented in this paper to take the advantages of the properties of the proposed circuit. PSpice simulation results using 0.18 μm CMOS technology are included as well to validate the functionality of the proposed circuit.     

Phase-margin enhancement technique for recycling folded cascode amplifier

A novel circuit technique for enhancing the phase-margin of the recycling folded cascode amplifier is presented. Compared to the conventional recycling folded cascade, using a high-speed current mirror, the proposed amplifier offers the advantage of cancellation of the first non-dominant pole, allowing the phase-margin to be enhanced without affecting the bandwidth. The proposed amplifier was implemented in CSMC standard 0.18 μm CMOS process. Simulation results show that the phase-margin enhancement of 20° is achieved without limiting the bandwidth.     

适用于高阶∑△调制器的全差分运算放大器的设计

比较了增益自举式共源共栅、折叠式共源共栅和套筒式A／A类三种常用的运算放大器结构．提出了一种可用于各种高阶∑△调制器的全差分运算放大器。采用SIMC0．35μm标准CMOS工艺．完成了含共模反馈电路的全差分套筒式运算跨导放大器的设计。仿真结果表明放大器的直流增益为84．5dB,单位增益带宽为199MHz,相位裕度为51°,电路工作可靠,性能优良。     

改进型折叠式共源共栅运算放大器电路的设计

在套筒式共源共栅、折叠式共源共栅运放中,折叠式共源共栅运算放大器凭借较大的输出摆幅和偏置电压的较低等优点而得到广泛运用。但是,折叠式的这些优势是以牺牲较大的功耗、较低的电流利用率而换取的。本文以提高电流利用率为着手点设计了一种改进的折叠式共源共栅运算放大器,在相同的电压和负载下改进的折叠式共源共栅运算放大器能显著提升跨导、压摆率和噪声性能。仿真结果表明在相同功耗和面积的条件下,改进的折叠式共源共栅运算放大器的单位增益带宽和压摆率是折叠式共源共栅运放的3倍。     

Enhancing general performance of folded cascode amplifier by recycling current

A modification to the conventional folded cascode transconductance amplifier is proposed. The proposed amplifier has the benefit of achieving a given set of design specifications while consuming a fraction of the power compared to the conventional folded cascode. Moreover, the proposed modification is robust even for low voltage applications.     

Low power low noise high speed tunable CMOS radiation detection system

This paper presents a design of low power and low noise, high speed readout front-end system for semiconductor detectors. The architecture comprises a folded cascode charge sensitive amplifier with gain enhancement, a pole-zero cancellation circuit and a complex shaper circuit with Gm-C topology. A local feedback amplifier based on a wide swing gain boosting scheme with dc level shifting has been used. The system has been fabricated in a 0.13-µm CMOS technology with a single 1.2-V supply voltage. Experimental results show the flexibility of the system where the key parameters, such as decay time, charge gain and peaking time can be tuned. For a nominal peaking time of 150 ns the power consumption of the entire channel is less than 5 mW. A power consumption-low noise tradeoff will be considered to match a detector capacitance of 5 pF. The output pulse has a peak amplitude of 200 mV for a charge of 10 fC from the detector and achieves a linearity better than 1% up to an input charge range of 12 fC.     

1-V power supply CMOS cascode amplifier

We design a folded cascode operational transconductance amplifier in a standard CMOS process, which has a measured 69-dB DC gain, a 2-MHz bandwidth, and compatible input- and output voltage levels at a 1-V power supply. This is done by a novel, current driven bulk (CDB) technique, which reduces the MOST threshold voltage by forcing a constant current though the transistor bulk terminal. We also look at limitations and improvements of this CDB technique     

一款高性能共源共栅运算放大器设计

基于CSMC 0.5μm标准CMOS工艺,采用复用型折叠式共源共栅结构,设计一种折叠式共源共栅运算放大器。该电路在5V电源电压下驱动5pF负载电容,采用Cadence公司的模拟仿真工具Spectre对电路进行仿真。结果表明,电路开环增益达到了71.7dB,单位增益带宽为52.79MHz,开环相位裕度为60.45°。     

Fast-settling CMOS Op-Amp with improved DC-gain

In this paper a new operational amplifier is presented based on the conventional folded cascode Op-Amp structure. A new method of positive feedback is used to increase DC-gain. Contrary to conventional designs this method does not decrease the speed of the folded cascode Op-Amp in the closed loop configuration. Simplicity is the other advantage of the proposed Op-Amp in comparison with the conventional structures. In this method, DC-gain improves by adding only two devices to the folded cascode structure. The additional devices neither decrease the bandwidth nor increase the power consumption, to a great extent. Proposed structure has been simulated by HSPICE software using level 49 parameters (BSIM3v3) in a typical 0.35 μm CMOS technology. HSPICE simulation confirms the theoretical estimated improvements.     

一种新型高速CMOS全差分运算放大器设计

设计了一种基于流水线模/数转换系统应用的低压高速CMOS全差分运算放大器。该运放采用了折叠式共源共栅放大结构与一种新型连续时间共模反馈电路相结合以达到高速度及较好的稳定性。设计基于SMIC 0.25μm CMOS标准工艺模型,在Cadence环境下对电路进行了Spectre仿真。在2.5V单电源电压下,驱动0.5pF负载时,开环增益为71.1dB,单位增益带宽为303MHz,相位裕度为52°,转换速率高达368.7V/μs,建立时间为12.4ns。     

Post-linearization with image rejection for high IIP3 and image-rejection ratio of a 17 GHz CMOS low noise amplifier

This study develops a post-linearization technique to simultaneously improve the input third-order intercept point (IIP3) and image-rejection ratio (IRR) of a 17 GHz low noise amplifier (LNA) in a 0.18 μm standard CMOS process. A third-order intermodulation distortion (IMD3) compensator constructed by a second-order notch filter was proposed to achieve both high linearity and image reject (IR) of the cascode LNA. The correlation between the post-linearization and IR techniques is analyzed and discussed. The measured LNA achieved a gain of 16.5 dB, a noise figure (NF) of 4.58 dB, an IIP3 of 0 dBm, and an IRR from 68 to 78 dB. The improvements of IIP3 and IRR are 11.7 and 46 dB, respectively, better than that of the LNA without the notch filter. The proposed IR LNA with total current dissipation of 4.8 mA under 1.8 V supply voltage and notch filter only dissipate a DC power of 2 mW.     

A BiCMOS wideband operational amplifier with 900 MHz gain-bandwidth and 90 dB DC gain

A fully differential operational amplifier has been designed and fabricated for a novel high resolution and high frequency analog-to-digital converter(>12-bit). The amplifier mainly consists of folded cascode structure with current source as output loads and common-mode feedback circuits. The technique of feedforward compensation is used in order to improve the settling time and gain bandwidth (GBW) of this amplifier. This amplifier is integrated in 0.8 mm BiCMOS process with an active die area of 0.1 mm². The DC gain of this amplifier is 90 dB. The GBW and phase margin of this amplifier is 900 MHz and 47°, respectively. The power dissipation is minimized by using BiCMOS technology and is about 25 mW for 2 pF load capacitance. This level of performance is competitive with CMOS and BiCMOS operational amplifier circuits previously reported by nearly two orders of magnitude.Ecole Polytechnique of the University of Montreal     

一种带有增益提高技术的高速CMOS运算放大器设计

设计了一种用于高速ADC中的高速高增益的全差分CMOS运算放大器。主运放采用带开关电容共模反馈的折叠式共源共栅结构,利用增益提高和三支路电流基准技术实现一个可用于12~14 bit精度,100 MS/s采样频率的高速流水线（Pipelined）ADC的运放。设计基于SMIC 0.25μm CMOS工艺,在Cadence环境下对电路进行Spectre仿真。仿真结果表明,在2.5 V单电源电压下驱动2 pF负载时,运放的直流增益可达到124 dB,单位增益带宽720 MHz,转换速率高达885 V/μs,达到0.1%的稳定精度的建立时间只需4 ns,共模抑制比153 dB。     

Leveraged Current Mirror Op Amp

A small change to the standard current mirror op amp configuration is shown to improve performance, with few, if any, disadvantages. Adding a pair of fixed current sources allows reduced operating-point current in the output stage, while the resulting leveraging effect increases slew rate. For equal total power dissipation, the new configuration improves DC gain and gain-bandwidth (GBW) over conventional current-mirror and folded cascode op amps, as shown by hand analyses and SPICE simulations. Also, because of increased input stage transconductance, the new configuration reduces thermal and flicker noise.