MOSCAP compensation of three-stage operational amplifiers: Sensitivity and robustness, modeling and analysis (original) (raw)
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2014 22nd Iranian Conference on Electrical Engineering (ICEE), 2014
a new single Miller Capacitor frequency compensation scheme for three stage amplifier is proposed. In conventional three-stage amplifier a differential feedback, from output of the second and the third stage is added to output of the first stage, which significantly improves Phase Margin and decreases compensation capacitor to less than 2% of the load capacitor value. Analyses show that the stability can be perfectly ensured. A three-stage amplifier has been simulated with and without a differential feedback in a 0.18µm CMOS .The proposed amplifier driving a 100pF capacitance load, achieved 1.39MHz gainbandwidth product and 90° Phase Margin with a 1.8V supply. An amplifier based on conventional nested Miller compensation (NMC) can just achieve less than 0.23MHz GBW with the same load, while using more than 100pF as compensation capacitor. So this method shows an improvement of a factor of 6 in GBW and reduction of a factor of 50 in the size of compensation capacitor. It is a suitable strategy for ON-CHIP compensation in comparison to other methods.
IJERT-Employment Compensation Capacitor to Improve Two Stage CMOS Operational Amplifier Design
International Journal of Engineering Research and Technology (IJERT), 2015
https://www.ijert.org/employment-compensation-capacitor-to-improve-two-stage-cmos-operational-amplifier-design https://www.ijert.org/research/employment-compensation-capacitor-to-improve-two-stage-cmos-operational-amplifier-design-IJERTV4IS040882.pdf This paper exhibits a decently characterized system for the design of two stage CMOS operational amplifiers according to given specifications. In order to achieve design operates at this limitation and analyze the effect of various aspect ratios on the characteristics of this operational amplifiers (Op-Amp), by CMOS technology. This paper focused on Employed Compensation capacitor to improved CMOS (Op-Amps) design work. Both the theoretical calculations and computer aided simulation analysis have been given in details. Design has been carried out in T-Spice as tool. The results accomplished by the simulation justify the given parameters and are very acceptable.
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A design procedure for an operational amplifier using indirect compensation is presented in this paper. Indirect compensation has inherent benefits in regards with power to speed trade-off. The technique has been seldom used in the past because a clear methodology for designing such an amplifier has not been provided. This paper develops the mathematical and analytical insight for designing an operational amplifier with this technique. The paper also provides a design strategy and an example to illustrate the use of the proposed design procedure.
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Analog Integrated Circuits and Signal Processing
This study describes a new and simple frequency compensation for three stages amplifiers based on revered nested Miller compensation (RNMC) structure. Using only one and small compensation capacitor reduced circuit complexity and die area while shows better performance compared to RNMC. Also the proposed method is unconditional stable due to cancellation of second dominant pole by a zero. Ample simulations are performed using HSPICE and TSMC 0.18 lm CMOS technology to verify robustness of presented circuit. Simulation results show 114 dB, 6.66 MHz and 360 lW as DC gain, GBW and power consumption respectively.
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COMPUTATIONAL RESEARCH PROGRESS IN APPLIED SCIENCE & ENGINEERING (CRPASE), 2020
CMOS operational amplifiers (Op-amp) are present integral components in various analog circuit systems. Adding frequency compensation elements is the only critical solution for avoiding Op-amp instability. This article presents a designed two-stage CMOS Op-amp using a miller capacitor, a nulling resistor, and a common-gate current buffer for compensation purposes. All the design parameters of the proposed Op-amp were determined based on the corresponding equations of gain, slew rate, phase margin, power dissipation, etc. In order to verify the parameter values, the developed Op-amp circuit was simulated in HSPICE, possessing two critical characteristics: Op-amp with miller capacitor and a robust bias circuit. Afterwards, the expected values from the theoretical section were compared with simulation results thus proving that the advanced method in this paper was validly designed and implemented. This technique promises a real-world scale Op-amp with high unity-gain, excessive input common-mode range voltage, reasonable gain bandwidth, and a practicable slew rate.