Non-Ideal Op-Amp Circuit Analysis

2010 ◽  
Vol 47 (1) ◽  
pp. 73-85
Author(s):  
Wuqiang Yang
Keyword(s):  
Input Impedance ◽  
Dynamic Behaviour ◽  
Open Loop ◽  
Loop Gain ◽  
Output Impedance ◽  
Circuit Performance ◽  
First Order ◽  
Op Amp ◽  
Op Amps ◽  
The Ideal

Op-amps are commonly used by instrumentation engineers. In the ideal case, the open-loop gain of an op-amp is regarded as infinite, the input impedance as infinite, and the output impedance as zero. In many cases, however, it is necessary to estimate the performance of an op-amp circuit with consideration of non-ideal parameters, and therefore it is necessary to analyse the non-ideal characteristics of the op-amp circuit. This paper discusses the effect on circuit performance of non-ideal parameters, i.e. finite open-loop gain, finite input impedance and non-zero output impedance of op-amps. A concept ‘loop gain’ is introduced and the dynamic behaviour, i.e. the frequency response, is analysed based on a first-order dynamic model.

CASCADABLE ALL-PASS AND NOTCH FILTER CONFIGURATIONS EMPLOYING TWO PLUS-TYPE DDCCs

2011 ◽  
Vol 20 (02) ◽  
pp. 329-347 ◽  
Author(s):  
SUDHANSHU MAHESHWARI ◽  
JITENDRA MOHAN ◽  
DURG SINGH CHAUHAN
Keyword(s):  
Input Impedance ◽  
Notch Filter ◽  
Second Order ◽  
Output Impedance ◽  
High Input ◽  
Notch Filters ◽  
High Input Impedance ◽  
Pspice Simulations ◽  
First Order ◽  
Theoretical Results

In this paper, twelve new circuit configurations for realization of first-order, second-order voltage-mode all-pass and notch filters with high input impedance and low output impedance are presented. The proposed circuit configurations use two plus type DDCCs, and two impedances. The circuits use one grounded capacitor and two grounded resistors for realizing first-order all-pass filters, and two grounded capacitors and two resistors for realizing second-order all-pass/notch filters. High input impedance and low output impedance of the configuration enable the circuits to be cascaded without additional buffers. As an application, a quadrature oscillator is realized. The theoretical results are verified with PSPICE simulations using 0.5 μm CMOS parameters.

Gallium-Arsenide JFET Op-Amp with High Open-Loop Gain

2021 ◽  
Author(s):  
N. N. Prokopenko ◽  
V. E. Chumakov ◽  
I. V. Pakhomov ◽  
A. V. Bugakova ◽  
D. Yu. Denisenko ◽  
...  
Keyword(s):  
Gallium Arsenide ◽  
Open Loop ◽  
Loop Gain ◽  
Op Amp

HISTORY AND PROGRESS OF THE KERWIN–HUELSMAN–NEWCOMB FILTER GENERATION AND OP AMP REALIZATIONS

2008 ◽  
Vol 17 (04) ◽  
pp. 637-658 ◽  
Author(s):  
AHMED M. SOLIMAN
Keyword(s):  
Q Factor ◽  
Spice Simulation ◽  
Gain Bandwidth ◽  
Circuit Performance ◽  
High Q ◽  
Op Amp ◽  
Op Amps ◽  
Compensation Methods ◽  
History Of ◽  
Finite Gain

The history of Kerwin–Huelsman–Newcomb (KHN) second-order filter is reviewed. A generation method of the KHN filter from passive RLC filter is presented. Two alternative forms of the KHN circuit using operational amplifier are reviewed. The effect of finite gain-bandwidth of the op amps is considered and expressions of the actual ω0 and Q are given. Two KHN circuits with inherently stable Q factor are also included. Two new partially compensated inverted KHN circuits are introduced. Active compensation methods to improve the KHN and the inverted KHN circuit performance for high Q designs are summarized. Spice simulation results are given. The progress of the KHN realizations using the current conveyor is also summarized briefly.

scholarly journals Super-Gain-Boosted AB-AB Fully Differential Miller Op-Amp with 156dB Open-loop Gain and 174MV/V MHZ pF/μW Figure of Merit in 130nm CMOS Technology

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Anindita Paul ◽  
Jaime Ramirez-Angulo ◽  
Alejandro Diaz Sanchez ◽  
Antonio J. Lopez-Martin ◽  
Ramon G. Carvajal ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Cmos Technology ◽  
Open Loop ◽  
Loop Gain ◽  
Fully Differential ◽  
Op Amp

A Study on Loop Gain Measurement Method Using Output Impedance in DC-DC Buck Converter

2018 ◽  
Vol E101.B (9) ◽  
pp. 1940-1948 ◽  
Author(s):  
Nobukazu TSUKIJI ◽  
Yasunori KOBORI ◽  
Haruo KOBAYASHI
Keyword(s):  
Measurement Method ◽  
Buck Converter ◽  
Loop Gain ◽  
Output Impedance ◽  
Gain Measurement

Improvement of Gain Accuracy and CMRR of Low Power Instrumentation Amplifier Using High Gain Operational Amplifiers

2020 ◽  
Vol 12 (3) ◽  
pp. 168-174
Author(s):  
Rashmi Sahu ◽  
Maitraiyee Konar ◽  
Sudip Kundu
Keyword(s):  
Low Power ◽  
Building Blocks ◽  
High Gain ◽  
The Other ◽  
Operational Amplifiers ◽  
Instrumentation Amplifier ◽  
Biomedical Signals ◽  
Op Amp ◽  
Op Amps ◽  
Multi Stage

Background: Sensing of biomedical signals is crucial for monitoring of various health conditions. These signals have a very low amplitude (in μV) and a small frequency range (<500 Hz). In the presence of various common-mode interferences, biomedical signals are difficult to detect. Instrumentation amplifiers (INAs) are usually preferred to detect these signals due to their high commonmode rejection ratio (CMRR). Gain accuracy and CMRR are two important parameters associated with any INA. This article, therefore, focuses on the improvement of the gain accuracy and CMRR of a low power INA topology. Objective: The objective of this article is to achieve high gain accuracy and CMRR of low power INA by having high gain operational amplifiers (Op-Amps), which are the building blocks of the INAs. Methods: For the implementation of the Op-Amps and the INAs, the Cadence Virtuoso tool was used. All the designs and implementation were realized in 0.18 μm CMOS technology. Results: Three different Op-Amp topologies namely single-stage differential Op-Amp, folded cascode Op-Amp, and multi-stage Op-Amp were implemented. Using these Op-Amp topologies separately, three Op-Amp-based INAs were realized and compared. The INA designed using the high gain multistage Op-Amp topology of low-frequency gain of 123.89 dB achieves a CMRR of 164.1 dB, with the INA’s gain accuracy as good as 99%, which is the best when compared to the other two INAs realized using the other two Op-Amp topologies implemented. Conclusion: Using very high gain Op-Amps as the building blocks of the INA improves the gain accuracy of the INA and enhances the CMRR of the INA. The three Op-Amp-based INA designed with the multi-stage Op-Amps shows state-of-the-art characteristics as its gain accuracy is 99% and CMRR is as high as 164.1 dB. The power consumed by this INA is 29.25 μW by operating on a power supply of ±0.9V. This makes this INA highly suitable for low power measurement applications.

Temperature control in a chemical reactor through variable area of the heat transfer surface. Experimental verification

1982 ◽  
Vol 47 (2) ◽  
pp. 446-453
Author(s):  
Josef Horák ◽  
František Jiráček ◽  
Libuše Ježová
Keyword(s):  
Batch Reactor ◽  
Exothermic Reaction ◽  
Chemical Reactor ◽  
Open Loop ◽  
Heat Transfer Surface ◽  
Laboratory Reactor ◽  
Hysteresis Control ◽  
Relay With Hysteresis ◽  
Rate Of Response ◽  
The Ideal

A possibility has been tested in the paper of the feed back control of temperature of the reaction mixture in a batch reactor with an exothermic reaction through the variable area of the cooling surface. The measurement were carried out in a laboratory reactor with a retractable cooler which was being immersed into the reaction mixture. The speed of motion of the cooler was sufficiently high permitting the process of immersion to be regarded as practically instantaneous. The aim of the control was to stabilize the set point temperature of the reaction mixture by a two-point controler. In dependence on the rate of response of the system to a change of the section variable either the ideal relay or the relay with hysteresis control algorithmus were used. The results of measurements showed that with the aid of a retractable cooler the temperature could be controlled safely even in those cases, in which the control by the variable flow rate of the coolant was unfeasible. The verification was carried out in the open-loop instable operating point of the reactor.

scholarly journals The Design of a Charge Pump Circuit and System with Input Impedance Modulation for a Flexible-Type Thermoelectric Generator with High-Output Impedance

Electronics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1212
Author(s):  
Kazuma Koketsu ◽  
Toru Tanzawa
Keyword(s):  
Input Impedance ◽  
Thermoelectric Generator ◽  
Charge Pump ◽  
Operating Voltage ◽  
Output Impedance ◽  
Two Phase ◽  
Pump System ◽  
High Output Impedance ◽  
A Charge ◽  
High Output

This paper describes a charge pump system for a flexible thermoelectric generator (TEG). Even though the TEG has high-output impedance, the system controls the input voltage to keep it higher than the minimum operating voltage by modulating the input impedance of the charge pump using two-phase operation with low- and high-input impedance modes. The average input impedance can be matched with the output impedance of the TEG. How the system can be designed is also described in detail. A design demonstration was performed for the TEG with 400 Ω. The fabricated system was also measured with a flexible-type TEG based on carbon nanotubes. Even with an output impedance of 1.4 kΩ, the system converted thermal energy into electric power of 30 μW at 2.5 V to the following sensor ICs.

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