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Analog Integrated Circuits
Analogue filter
MOS transistor
Basic analogue stages
CMOS opamp
Course Analog Integrated Circuits Libor RUFER & Salvador MIR


Description

Aims

The objective of the course is to show the physical background and the approaches that are used in the design of microelectronic circuits.

The objectives of this course are to:

  • Understand the solid state behaviour of basic components of integrated circuits.
  • Understand the concept of electronic components modelling.
  • Understand the principles of basic analogue stages used in integrated circuits.

The course suits especially well for students who aim for R&D tasks.

Contents

The course gives an introduction to microelectronic circuits, design of basic building blocks and their applications. Following issues will be discussed:

  • Analogue signals and systems
  • MOS transistor
  • Basic analogue stages
  • CMOS operational amplifier


Introduction

Analogue integrated circuits have always been a key part of modern communications devices and other applications where miniaturization, low cost and low power dictate an integrated circuit solution. Analogue circuits, unlikely to digital circuits, are dealing with signals free to vary from zero to full power supply voltage. This course will deal with integrated circuits (ICs) components that are networks of interconnected components manufactured on a single wafer of semiconducting material. Most integrated circuits provide the same functionality as "discrete" semiconductor circuits at higher levels of reliability and at a fraction of the cost. Usually, discrete-component circuit construction is favoured only when power dissipation levels are too high for integrated circuits to handle. This course is concentrating solely on MOS circuits, which represent more than 99% of the digital IC market today. One part of this course is devoted to the foundations of signal processing and filtering that are very important in the current trend towards analogue/digital, i.e., mixed-mode signal processing on a chip.


Prerequisite


Course Tasks

Task 1: Analogue filter

Design a second-order band-pass filter using Multiple Feedback (MFB) topology.
Required filter characteristics are as follows:

Centre frequency fm = 1 kHz
Quality factor Q = 10
Gain Am = -2

Assume a capacitor value of C = 100 nF and find the values of resistances for the filter implementation.

Task 2: MOS transistor

Investigate the basic physical factors that determine and limit the performance of MOS transistors and other MOS structures.
Understand the basic characteristics and models of MOS transistors.

Task 3: Basic analogue stages

Consider a differential-input, single-ended-output MOS gain stage shown in the following figure:

 

Suppose the following dimensions and parameters of the MOS structure:

      All transistors have the same gate width to length ratio W/L = (100 μm) / (1.6 μm),

      Mobility of electrons near the silicon surface μn = 0.05 m2V-1s-1,

      Gate capacitance per unit area Cox = 1.9 10-3 pF μm-2,

      Transistor threshold voltage Vtn = 0.8 V,

      Small-signal drain-source resistance rDS = 8 106 L / ID,

      Bias current Ibias = 200 μA.

 

  1. Find the output impedance rout.
  2. Find the gain from the differential input Vin to the output Vout.

Task 4: CMOS opamp

Consider the two-stage circuit architecture for CMOS operational amplifier. Discuss its overall gain, and investigate its frequency response. Describe its possible frequency compensation. Finally show the basic circuits using an operational amplifier in a negative feedback configuration.
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