Multistage Amplifiers

2018 ◽  
pp. 181-243
Author(s):  
Amir M. Sodagar
Keyword(s):  
Multistage Amplifiers

A Note on the Stability of a Valve Amplifier

1929 ◽  
Vol 25 (4) ◽  
pp. 508-513 ◽  
Author(s):  
E. B. Moullin
Keyword(s):  
Natural Frequency ◽  
Frequency Instability ◽  
Oscillatory Circuit ◽  
Exact Condition ◽  
Multistage Amplifiers ◽  
The Stability

This paper considers the stability of a valve amplifier which has an oscillatory circuit in the grid and in the anode circuit. An exact condition for stability is obtained for circuits which have no resistance, and it is shown that when both circuits have the same natural frequency instability is then impossible if the anode inductance exceeds μ times the grid circuit inductance. This condition is believed to be new; in practice it is unnecessarily severe, but it is believed that stability should be sought by increasing the anode inductance and the grid circuit capacity. The stability of circuits which have resistance is too cumbersome to express generally, but it is discussed on broad principles; the stability and amplification of multistage amplifiers are also considered briefly. The following papers should be compared with the present one.

scholarly journals Recent Advances on the Design of High-Gain Wideband Operational Transconductance Amplifiers

VLSI Design ◽  
2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Rida Assaad ◽  
Jose Silva-Martinez
Keyword(s):  
High Frequency ◽  
High Gain ◽  
Feed Forward ◽  
Operational Transconductance Amplifiers ◽  
Miller Compensation ◽  
Multistage Amplifiers ◽  
Dc Gain ◽  
Folded Cascode ◽  
Transconductance Amplifiers ◽  
Better Than

Feed-forward techniques are explored for the design of high-frequency Operational Transconductance Amplifiers (OTAs). For single-stage amplifiers, a recycling folded-cascode OTA presents twice the GBW (197.2 MHz versus 106.3 MHz) and more than twice the slew rate (231.1 V/s versus 99.3 V/s) as a conventional folded cascode OTA for the same load, power consumption, and transistor dimensions. It is demonstrated that the efficiency of the recycling folded-cascode is equivalent to that of a telescopic OTA. As for multistage amplifiers, a No-Capacitor Feed-Forward (NCFF) compensation scheme which uses a high-frequency pole-zero doublet to obtain greater than 90 dB DC gain, GBW of 325 MHz and better than phase margin is discussed. The settling-time- of the NCFF topology can be faster than that of OTAs with Miller compensation. Experimental results for the recycling folded-cascode OTA fabricated in TSMC 0.18 m CMOS, and results of the NCFF demonstrate the efficiency and feasibility of the feed-forward schemes.

Impedance Adapting Compensation for Low-Power Multistage Amplifiers

2011 ◽  
Vol 46 (2) ◽  
pp. 445-451 ◽  
Author(s):  
Xiaohong Peng ◽  
Willy Sansen ◽  
Ligang Hou ◽  
Jinhui Wang ◽  
Wuchen Wu
Keyword(s):  
Low Power ◽  
Multistage Amplifiers

A reliable model for the compensation loop of multistage amplifiers at high frequency

Circuit World ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 268-278
Author(s):  
Hamed Aminzadeh
Keyword(s):  
Frequency Response ◽  
Feedback Loop ◽  
Closed Loop ◽  
Cmos Process ◽  
Frequency Compensation ◽  
Content Type ◽  
Multistage Amplifiers ◽  
Proposed Model ◽  
Reliable Model ◽  
Poles And Zeros

Purpose Multistage amplifiers require a reliable frequency compensation solution to remain stable in a closed-loop configuration. A frequency compensation scheme creates an inner negative feedback loop amongst different amplifying stages and shapes the frequency response such that an unconditionally stable single-pole amplifier results for closed-loop operation. The frequency compensation loop is thus responsible for the placement of the poles and zeros and the final stability of multistage amplifiers. An amplifier incorporating a sophisticated frequency compensation network cannot be, however, analyzed in the presence of a complex ac feedback loop. The purpose of this study is to provide a reliable model for the compensation loop of multistage amplifiers at the higher frequencies. Design/methodology/approach In this paper, the major part of the amplifier, including a two-port network comprising the compensation network, is characterized using a reliable feedback model. Findings The model integrates all the frequency-dependent components of the frequency compensation network, and it can evaluate the nondominant real or complex poles of an amplifier. Originality/value The reliability of the proposed model is verified through analysis of the frequency response of the amplifiers and by comparing the analytic results with the simulation results in standard CMOS process.

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