Common gate

Common gate

Common gate refers to a type of single-transistor FET amplifier where the input signal is applied to the source terminal, the output is taken from the drain terminal, and the gate terminal is connected to a constant voltage. This configuration ensures proper operating conditions and produces output voltage at the drain terminal. The common gate amplifier has a low input impedance, making matching easier and ensuring stable performance without neutralization. Additionally, the common gate transistor increases the input-output reverse isolation, gain, and stability of the amplifier.From: Comprehensive Dictionary of Electrical Engineering [2019], MOS Amplifier Design Methodology for Optimum Performance [2020], Fet Technology and Application [2020], Design and Analysis of 30 GHz CMOS Low-Noise Amplifier for 5G Communication Applications [2023]

Electronic Circuits

View Chapter

Purchase Book

Published in Dale R. Patrick, Stephen W. Fardo, Electricity and Electronics Fundamentals, 2020

Dale R. Patrick, Stephen W. Fardo

The common-gate FET amplifier is similar in many respects to the common-base bipolar transistor circuit. The input signal is applied to the source-gate and the output appears across the drain-gate. The common-gate amplifier is capable of voltage gain but has a current gain capability that is less than 1. JFETs, E-MOSFETs, and D-MOSFETs may all be used as common-gate amplifiers.

Where Small-Signal FETs Are Found

View Chapter

Purchase Book

Published in Edwin S. Oxner, Fet Technology and Application, 2020

Edwin S. Oxner

The common-gate amplifier offering a low input impedance makes matching easier and ensures stable performance without neutralization. Unfortunately, the lowest noise figure is not always accompanied by the highest gain.

MOS Amplifier Design Methodology for Optimum Performance

View Article

Journal Information

Published in IETE Journal of Research, 2020

Abir J. Mondal, Paromita Bhattacharjee, Pinaki Chakraborty, Bidyut K. Bhattacharyya

Unlike the other single-stage amplifiers, the common gate (CG) stage portrayed in Figure 5 has its gate biased at a desired potential ensuring proper operating conditions, accepts the input signal at its source terminal, and produces output voltage Vout at drain terminal. Figure 6 represents the schematic of a cascade of a CS and CG stage called cascode amplifier. Here, the change in overdrive voltage, Vin-Vth1 is converted into a small signal drain current Id using M1. Thereafter, Id is routed through load resistor Rd by M2 to produce an output voltage Vout at the drain terminal of M2.

Explore chapters and articles related to this topic

Electronic Circuits

Where Small-Signal FETs Are Found

MOS Amplifier Design Methodology for Optimum Performance