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ECE 340 ELECTRONICS I. MOS APPLICATIONS AND BIASING. MOSFET REGIONS OF OPERATION. CUT OFF LINEAR, OHMIC, TRIODE SATURATION. CUT OFF REGION OF OPERATION. LINEAR, OHMIC, TRIODE REGION OF OPERATION. SATURATION REGION OF OPERATION. MOSFET CHARACTERISTICS. 1.5mA. I D. 1.0mA. v GS3.
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ECE 340ELECTRONICS I MOS APPLICATIONS AND BIASING
MOSFET REGIONS OF OPERATION • CUT OFF • LINEAR, OHMIC, TRIODE • SATURATION
MOSFET CHARACTERISTICS 1.5mA ID 1.0mA vGS3 Linear, Ohmic, Triode ROP Saturation ROP vGS2 0.5mA vGS1 Cutoff ROP 0mA 0V 2V 4V 6V 8V 10V 12V vDS
MOSFET BIASING • SELECTION OF GATE TO SOURCE VOLTAGE • PRODUCES DC DRAIN TO SOURCE VOLTAGE • PRODUCES DC DRAIN CURRENT • DEFINES REGION OF OPERATION
DC LOAD LINE • INPUT DC BIAS EQUATION • OUTPUT DC BIAS EQUATION • LINEAR EQUATION WITH SLOPE DETERMINED BY EXTERNAL RESISTORS
VDD ID ID RD RD + + VDS VDD VDS VGG + + - - VGS VGS VGG - - RS RS MOSFET BIAS CIRCUIT
INPUT EQUATION • SETS OR SELECTS DC GATE TO SOURCE VOLTAGE • SETS OR SELECTS DC DRAIN CURRENT • CONSTRUCTED BY PERFORMING KVL ON INPUT PORTION OF THE CIRCUIT
OUTPUT EQUATION • SELECTS OR SETS DC DRAIN TO SOURCE VOLTAGE • SELECTS OR SETS DC DRAIN CURRENT • CONSTRUCTED BY PERFORMING KVL ON OUTPUT PORTION OF THE CIRCUIT
LOAD LINE EQUATION • USED TO SELECT BIAS PARAMETERS VGS, VDS, AND ID.
ID 1.5mA vGS3 1.0mA Linear, Ohmic, Triode ROP Saturation ROP LOAD LINE vGS2 0.5mA vGS1 Cutoff ROP 0mA 0V 2V 4V 6V 8V 10V 12V vDS
BIASING CIRCUITS • USED TO ESTABLISH - VGG (GATE VOLTAGE) - ID (DRAIN CURRENT) -VDS (DRAIN TO SOURCE VOLTAGE) • USES ONE OR TWO POWER SUPPLIES
VDD ID RD RS VSS USING TWO POWER SUPPLIES + VDS -
VDD IX ID IX ID R1 RD R1 RD + + VDD IG = 0 IG = 0 VDS VDS + + - + + - VGS VGS - - VGG R2 RS VGG R2 RS - - USING ONE POWER SUPPLY