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Active Filter Design Using Operational Transconductance Amplifiers: A Tutorial
 IEEE Circuits and Device Magazine
, 1985
"... Basic properties of the Operational Transconductance Amplifier (OTA) are discussed. Applications of the OTA in voltagecontrolled amplifiers, filters, and impedances are presented. A versatile family of voltagecontrolled filter sections suitable for systematic design requirements is described. The ..."
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Cited by 36 (4 self)
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Basic properties of the Operational Transconductance Amplifier (OTA) are discussed. Applications of the OTA in voltagecontrolled amplifiers, filters, and impedances are presented. A versatile family of voltagecontrolled filter sections suitable for systematic design requirements is described. The total number of components used in these circuits is small, and the design equations and voltagecontrol characteristics are attractive. Limitations as well as practical considerations of OTA based filters using commercially available bipolar OTAs are discussed. Applications of OTAs in continuoustime monolithic filters are considered.
Power Analysis and Optimal Design of Opamps for Oversampled Converters
 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II
, 1999
"... In this paper, we address three issues related to the design of opamps for oversampled converters: the theoretical minimumpower bound for an ideal opamp, the best opamp choice in terms of power dissipation, and the best design strategy to reduce power dissipation. To be able to do so, we develop a ..."
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Cited by 3 (0 self)
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In this paper, we address three issues related to the design of opamps for oversampled converters: the theoretical minimumpower bound for an ideal opamp, the best opamp choice in terms of power dissipation, and the best design strategy to reduce power dissipation. To be able to do so, we develop a model that captures the dynamics of the integrator inside the modulator. Based on this model, power dissipation for various opamp topologies is computed and compared with each other. We show that classA opamps can consume one to six times the current consumed by an idealized classAB opamp, though the savings for practical classAB opamps is likely to be lower. For highresolution applications, classA topologies are most optimal, while for lower resolution lower power applications, classAB opamps may be more suitable. We further demonstrate a design strategy with the help of an example that can be used to minimize the power dissipation for classA opamps.
Design of LowPower Analog Drivers Based on SlewRate Enhancement Circuits for CMOS LowDropout Regulators
"... Abstract—Lowpower analog driver based on a singlestage amplifier with an embedded currentdetection slewrate enhancement (SRE) circuit is presented. By developing a systematic way to design both the response time and optimal sizing of driving transistors in the SRE circuit, the SRE circuit can be ..."
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Cited by 1 (0 self)
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Abstract—Lowpower analog driver based on a singlestage amplifier with an embedded currentdetection slewrate enhancement (SRE) circuit is presented. By developing a systematic way to design both the response time and optimal sizing of driving transistors in the SRE circuit, the SRE circuit can be controlled to turn on or turn off properly. In addition, the analog driver only dissipates low static power and its transient responses are significantly improved without transient overshoot when driving large capacitive loads. Implemented in a 0.6 m CMOS process, a currentmirror amplifier with the currentdetection SRE circuit has achieved over 43 times improvement in both slew rate and 1 % settling time when driving a 470pF load capacitor. When the proposed analog driver is employed in a 50mA CMOS lowdropout regulator (LDO), the resultant load transient response of the LDO has 2fold improvement for the maximum loadcurrent change, while the total quiescent current is only increased by less than 3%. Index Terms—Amplifiers, analog driver, lowdropout regulator (LDO), slew rate, slewrate enhancement (SRE) circuit, transient responses. I.
Low Voltage High Gain Linear Class AB CMOS OTA with DC Level Input Stage
"... Abstract—This paper presents a lowvoltage lowpower differential linear transconductor with near railtorail input swing. Based on the currentmirror OTA topology, the proposed transconductor combines the Flipped Voltage Follower (FVF) technique to linearize the transconductor behavior that leads ..."
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Abstract—This paper presents a lowvoltage lowpower differential linear transconductor with near railtorail input swing. Based on the currentmirror OTA topology, the proposed transconductor combines the Flipped Voltage Follower (FVF) technique to linearize the transconductor behavior that leads to classAB linear operation and the virtual transistor technique to lower the effective threshold voltages of the transistors which offers an advantage in terms of low supply requirement. Design of the OTA has been discussed. It operates at supply voltages of about ±0.8V. Simulation results for 0.18µm TSMC CMOS technology show a good input range of 1Vpp with a high DC gain of 81.53dB and a total harmonic distortion of40dB at 1MHz for an input of 1Vpp. The main aim of this paper is to present and compare new OTA design with high transconductance, which has a potential to be used in low voltage applications. Keywords—Amplifier class AB, current mirror, flipped voltage follower, low voltage. W I.
Special Papers MOS Operational Amplifier Design— A Tutorial Overview
"... AbstractThis paper presents an overview of current design techniques for operational amplifiers implemented in CMOS and NMOS technology at a tutorial level. Primary emphasis is placed on CMOS amplifiers because of their more widespread use. Factors affecting voltage gain, input,noise, offsets, comm ..."
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AbstractThis paper presents an overview of current design techniques for operational amplifiers implemented in CMOS and NMOS technology at a tutorial level. Primary emphasis is placed on CMOS amplifiers because of their more widespread use. Factors affecting voltage gain, input,noise, offsets, common mode and power supply rejection, power dissipation, and transient response are considered for the traditional bipolarderived twostage architecture. Alternative circuit approaches for optimization of particular performance aapects are summarized, and examples are given. I.
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"... ,4mtract — MOS technology scaling requires the use of lower supply voltages. Analog circuits operating from a low supply and achieving a sufficiently farge dynamic range must be designed if analogidigital interfaces are to be implemented in scaled technologies. This paper describes a highperforman ..."
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,4mtract — MOS technology scaling requires the use of lower supply voltages. Analog circuits operating from a low supply and achieving a sufficiently farge dynamic range must be designed if analogidigital interfaces are to be implemented in scaled technologies. This paper describes a highperformance fifthorder lowpass switchedcapacitor filter operating from a single 5V supply. The filter uses a fully differential topology combined with inputtooutput class A B amplifier design, dynamic biasing, and switchedcapacitor commonmode feedback (CMFB). An experimental prototype fabricated in a 5 p m CMOS technology requires orlly 350 pW of power to meet the PCM channel filter requirements. Typical measured results are a dynamic range of 92 dB, a supply rejection (PSRR) of 40 dB over the entire Nyquist range, and a total harmonic distortion (THD) of – 73 dB for a 2V rms dlfferentiaf output signal. The chip active area is about 3900 milz.
October 20, 1998 5:14 Pm 1
"... In low power current mode signal processing circuits it is many times required to use current mirrors to replicate and amplify/attenuate current signals, and to clamp the voltage of nodes with high parasitic capacitances so that the smallest currents do not introduce unacceptable delays. The use of ..."
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In low power current mode signal processing circuits it is many times required to use current mirrors to replicate and amplify/attenuate current signals, and to clamp the voltage of nodes with high parasitic capacitances so that the smallest currents do not introduce unacceptable delays. The use of tunable activeinput current mirrors would meet both requirements. In conventional active input current mirrors stability compensation is required. Furthermore, once stabilized, input current cannot be made arbitrarily small. In this paper we introduce two new activeinput current mirrors that clamp their input node to a given voltage. One of them does not require compensation, while the other may require under some circumstances, but for both input current may take any value. The mirrors can operate with their transistors biased in strong inversion, weak inversion or even as CMOS compatible lateral bipolar devices. If biased in weak inversion or as lateral bipolars, the current mirror gain ...
To Apply These Results for Developing New Robust Nonlinear Control Laws Based on Dynamic Neural Networks.
"... In low power current mode signal processing circuits it is often necessary to use current mirrors to replicate and amplify/attenuate current signals and clamp the voltage of nodes with high parasitic capacitances so that the smallest currents do not introduce unacceptable delays. The use of tunable ..."
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In low power current mode signal processing circuits it is often necessary to use current mirrors to replicate and amplify/attenuate current signals and clamp the voltage of nodes with high parasitic capacitances so that the smallest currents do not introduce unacceptable delays. The use of tunable activeinput current mirrors would meet both requirements. In conventional activeinput current mirrors, stability compensation is required. Furthermore, once stabilized, the input current cannot be made arbitrarily small. In this paper we introduce two new activeinput current mirrors that clamp their input node to a given voltage. One of them does not require compensation, while the other may under some circumstances. However, for both, the input current may take any value. The mirrors can operate with their transistors biased in strong inversion, weak inversion, or even as CMOS compatible lateral bipolar devices. If it is biased in weak inversion or as lateral bipolars, the current mirror...
A Quad CMOS SingleSupply Op Amp with RailtoRail Output Swing
"... .&tract —The realization of a commercially viable, generalpurpose quad CMOS amplifier will be presented along with discussions of the tradeoffs involved in such a design. The amplifierfeatures an output swing that extends to either supply rail. Together witfs an input commonmode range that in ..."
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.&tract —The realization of a commercially viable, generalpurpose quad CMOS amplifier will be presented along with discussions of the tradeoffs involved in such a design. The amplifierfeatures an output swing that extends to either supply rail. Together witfs an input commonmode range that includes ground, the device is especially well suited for singlesupply operation and is fully specified for operation from 5 to 15 V over a temperature range of – 55 to + 12S”C. Unlike earlier designs that sacrificed performance in the areas of input offset voltage, offset voltage drift, input noise voltage, voltage gain, and load driving capability, this implementation offers performancethat equals or exceeds that of popular generafpurpose quads of bipolar or B1FET ’ construction. On a 5V supply the typicaf VO,is 1 mV, VO,drift is 1.3 pV/OC, lkHz noise is 36 nV/~Hz, and gain is one million into a 600Q load. This device achieves its performance through both circuit design and layout techniques a$ opposed to special analog CMOS processing, thus lending itself to use on system chips built with the latest digital CMOS technology. I.