Amplification Factor 𝝁

Introduction of Field Effect Transistors Distinction between a BJT and FET Junction Field Effect Transistor (JFET) N Channel JFET Summary of JFET Operation Mutual or Transfer Characteristic of n-channel JFET Amplification Factor 𝝁 Definition of Parameters p-Channel JFET

Introduction of Metal Oxide Semiconductor Field Effect Transistor - Mosfet Terminals in MOSFET Physical structure of MOSFET MOSFET Working Operation Summary of Operation MOSFET - N Type MOSFET Operation How does Drain current flow MOSFET operation More about Threshold Voltage Current vs Voltage Characteristics - Derivation Non Ideal Current -Voltage Effects or Second Order Effects Short Channel Effects MOSFET Device Capacitances MOSFET Large and Small signal Model pMOSFET Small SIgnal Model To use MOSFET device as a Capacitor nMOSFET as Capacitor- Working

Single Stage Amplifiers Common Source CS Stage with Diode-Connected Load Circuit to measure the Equivalent Resistance Common Drain Stage or Source Follower Common Gate Amplifier Large Signal Behavior Calculation of Input Resistance of a Common Gate Stage

Inverter with Enhancement n- Type MOS as Load Inverter with Linear Enhancement Type Load

Amplification Factor 𝝁

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Amplification Factor 𝝁

Another parameter of importance is called the Amplification factor and is represented by the symbol 𝝁

This is obtained from the plot drawn between the VDS and VGS(negative value) keeping the value of the Drain current ID constant.

Figure 10: Amplification Characteristic

The Amplification factor 𝝁 represents the maximum amount of amplification the JFET can produce.

Relationship between the Amplification Factor 𝝁, Transconductance gm and Drain Resistance rd:

From equation (1), it may be noted that i_D is the instantaneous value of the Drain current, v_DS is the instantaneous value of Drain - Source Voltage and v_GS is the instantaneous value of the Gate - Source voltage.

It may be noted here that the word instantaneous value represents the variable DC value.

It may also be observed from the equation (1) that the total variation in the value of the Drain current i_D is the sum of the variations in v_DS and v_GS.

Ilustration:

For this look at the equation (2).

Here

v_DS → Variable DC

V_DS → Pure DC

v_ds → Pure AC

Expand the equation (1) using Taylor's expansion, we get

From (3) note the following:

∆v_DS → Small change in v_DS

∆v_GS → Small change in v_GS

∆ i_D → The corresponding change in i_D

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Amplification Factor 𝝁

Field Effect Transistors

Field Effect Transistors

Metal Oxide Semiconductor Field Effect Transistor - Mosfet

Metal Oxide Semiconductor Field Effect Transistor - Mosfet

Amplifiers

Amplifiers

Inverters

Inverters

Amplification Factor 𝝁