Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

MOS Small-Signal Model: Simplifying Analog Circuit Analysis

In course

EE-320: Analog IC design

Introduction to the design of analog CMOS integrated circuits at the transistor level. Understanding and design of basic structures. ...

Description

This lecture covers the small-signal model of MOS devices, focusing on simplifying calculations around the operating point. It explains how this model can be derived for MOSFETs biased in the saturation region, including the linear resistor and capacitances involved. The lecture also discusses the small-signal model with body effect, highlighting the impact of varying voltages on the behavior of MOS devices.

Instructor

Mahsa Shoaran

Official source

Ontological neighbourhood

Physics

Condensed matter physics: Solid-state physics

Related concepts (25)

Threshold voltage

The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency. When referring to a junction field-effect transistor (JFET), the threshold voltage is often called pinch-off voltage instead.

MOSFET

The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal-insulator-semiconductor field-effect transistor (MISFET) is a term almost synonymous with MOSFET.

Small-signal model

Small-signal modeling is a common analysis technique in electronics engineering used to approximate the behavior of electronic circuits containing nonlinear devices with linear equations. It is applicable to electronic circuits in which the AC signals (i.e., the time-varying currents and voltages in the circuit) are small relative to the DC bias currents and voltages. A small-signal model is an AC equivalent circuit in which the nonlinear circuit elements are replaced by linear elements whose values are given by the first-order (linear) approximation of their characteristic curve near the bias point.

Field-effect transistor

The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source. FETs are also known as unipolar transistors since they involve single-carrier-type operation.

Semiconductor device

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum (typically liberated by thermionic emission) or as free electrons and ions through an ionized gas.

Related lectures (58)

Review of BJT and MOS

Provides a detailed review of Bipolar Junction Transistor (BJT) and Metal-Oxide-Semiconductor (MOS) devices.

Small-Signal Model: MOS Capacitances

Covers the small-signal model of MOS devices and signal amplification in analog circuits.

Second order effects: Body Effect and Channel-Length Modulation

Explores the impact of Body Effect and Channel-Length Modulation on MOSFET performance.

Second order Effects: Body Effect and Channel-Length Modulation

Explores the Body Effect, Channel-Length Modulation, and Subthreshold Conduction in MOSFETs, crucial for circuit design.

MOS Transistor Operation: Triode vs Saturation