Post on 04-Feb-2016
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BJT DC BIASING
For the BJT to be biased in its linear or active operating region, the following must be true:• The base-emitter
junction must be forward-biased
• The base-collector junction must be reverse-biased
Operation in cut-off, saturation and linear regions of the BJT characteristics are provides as follows:
1. Linear-region operation: Base-emitter junction forward biased Base-collector junction reverse-biased
2. Cutoff-region operation: Base-emitter junction reverse biased
3. Saturation-region operation Base-emitter junction forward biased Base-collector junction forward biased
FIXED-BIAS CIRCUIT
FORMULAS INVOLVEDBase-emitter Base-collector
EXAMPLE 1
Determine the following for the fixed-bias configuration.
a) IBQ and ICQ
b) VCEQ
c) VB and VC
d) VBC
EMITTER-STABILIZED BIAS CIRCUIT
Contains an emitter resistor to improve stability level over that of the fixed-bias configuration.
BASE EMITTER LOOP
COLLECTOR-EMITTER LOOP
EXAMPLE 2For the emitter bias network, determine:
a) IB
b) IC
c) VCE
d) VC
e) VE
f) VB
g) VBC
VOLTAGE-DIVIDER BIAS
Determine the dc bias voltage VCE and the current IC.
COLLECTOR FEEDBACK
BASE-EMITTER LOOP
COLLECTOR-EMITTER LOOP
EXAMPLE 4
Determine Ic and VCE
EMITTER-FOLLOWER CONFIGURATION
EXAMPLE 5
Determine IE and VCE
COMMON-BASE CONFIGURATION
EXAMPLE 6Determine:
a. IE
b. IB
c. VCE
d. VCB