Single Stage Amplifiers

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Single Stage Amplifiers

• Subho Chatterjee
• Advanced VLSI Design Lab
• IIT Kharagpur

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Some Fundamental Issues

• Large Signal and Small signal analysis.
• The i/p o/p characteristic is approximated as
  
• y(t) a0a1x(t)
• a0 is the operating(bias) point
• a1 is the small signal gain
• CONDITION a0gtgta1x(t)

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MOS Transistor
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Ids vs Vds

Long Channel
Short Channel
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MOSFET Operating Regions

• Strong Inversion VGS gt VT
• Linear (Resistive) VDS lt VDSAT
• Saturated (Constant Current) VDS ? VDSAT
• Weak Inversion (Sub-Threshold) VGS ? VT
• Where VDSATVGS-VT

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Transistor in Linear Region
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Transistor in Saturation
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Current Equations
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Parameters
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Small Signal Model
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Single Stage Amplifier Contents

• Fundamentals
• Basic Amplifiers Low Frequency Analysis
• Basic Amplifiers High Frequency Analysis

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Fundamentals

• DC Operating Point Load line
• MOSFET intrinsic Capacitances

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DC Operating Point Load Line
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AMPLIFICATION
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High Freq. Small Signal Model
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MOSFET Intrinsic Capacitances
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Single Stage Amplifiers CS, CD, and CG Stage
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Common Source Stage Voltage Gain
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Loads for basic amplifiers

• Diode Connected Load

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Loads for basic amplifiers

• Source degeneration

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Cascode Stage

• Small Signal Analysis
• Rout

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Common Drain Stage (Buffer)
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Common Gate Stage (Low Input Impedance)
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Summary
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Loads for basic amplifiers
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Basic Amplifiers High Frequency Analysis
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Frequency Analysis
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Frequency Analysis

• Bode Plot

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Bandwidth Comparison
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• THANK YOU!