Circuit Analysis and Optimization

Integrated MOS Amplifier

1st Laboratory Session (4 meetings) on April 7, 2014

Integrated MOS amplifiers are probably the most common and highly important devices in majority of analog- or mixed-signal integrated circuits. Wherever analog signals are in place, an OPAMP (OPerational AMPlifier) plays key rule in amplifying, filtering, and further signal processing. In this session, you will learn how to use SpiceOPUS to simulate the overall electrical behaviour of such circuit, including operating point, DC charasteristics (differential gain, common mode gain), AC charasteristics (gain, phase, bandwidth, margins), transient - time-domain characteristics and noise. As a professional analog circuit designer, you will probably use methods of this session on a regular basis.

First things first - SpiceOPUS and netlists.

In the beginning, you will learn how to describe a circuit in a Spice-friendly input format. Circuit is typically described in a form of a file, called netlist. The structure of a file is like follows:


        Circuit name
        circuit_description
        .control
        NUTMEG_commands
        .endc
        .end

The first line (Circuit name) is never interpreted. circuit_description is the actual description of circuit topology and parameters. You will practise this part on the first meeting. .control is a command, that tells Spice that circuit description is over. NUTMEG_commands are commands that execute various types of analysis. .endc tells Spice that command block has ended, and .end marks the end of a netlist.
Since the first session is about MOS amplifier, lets take a look on how a single MOS transistor is being described in a netlist. For example, this is how transistor M4 is correctly described:


	m4 (net003 inn net002 vss) nmosmod w=7.353e-5 l=2.370e-6 m=2

Your first task will be to encode the whole OPAMP circuit in this manner. You will also add power supply and signal-source elements to bring this circuit into life.

OP Analysis

Operating Point (OP) Analysis is the most basic simulation of a circuit behaviour. You will learn how to check if the circuit is alive using OP analysis.

DC Analysis and Plotting of Simulation Results

Direct Current (DC) Analysis is a set of multiple OP analyses, but with some altering parameters. Let's say you want to inspect the dependance of ouput voltage to the changes on input differential voltage or even power supply - you can use a DC analysis to do that.

In order to better understand and imagine the simulation results, you will learn how to plot, interpret and visualise using SpiceOPUS.

AC Analysis

NOISE Analysis

20 dB Amplifier Using Integrated OPAMP - Various Analyses

Lines, Atennuators, Sub-circuits

2nd Laboratory Session on April 2, 2014

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About the course

This is an intermediate level course about blablabla... This is a compulsory course in the 1. semester of the Master’s degree curriculum “Electronics”. The aim is to introduce students to the theoretical background of analog circuit simulation. The course also involves laboratory work in the advanced field of circuit simulation and optimization with SPICE OPUS.

Staff

Lecturer:

prof. dr. Árpád Bürmen

Teaching Assistant:

as. Žiga Rojec

Required knowledge

Basics of Electromagnetics Physics Mathematics I, II, III