Electronics Circuit Design

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3. Cascade and Cascode configurations (12.2 -
12.5)

• Cascaded amplifiers
• Cascode amplifiers
• Darlington pair
• Feedback pair

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Cascaded amplifiers
Cascaded amplifiers consists of two or more
stages of the basic BJT and/or FET circuits each
of which utilize individual power supply VCC
Cascaded amplifiers are used to obtain higher
voltage amplification, or matching of the input
impedance with the transducer and matching the
output impedances with the loading of the
following stage.
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Example1
(a) Find re for both BJT
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(b) Find Rin, Ro, Av, and Ai of the cascade
amplifier
Input resistance 1
Output resistance 2
Voltage gain 1
Voltage gain 2
Voltage gain overall
Current gain
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Example2
(a) Find gm of the FET
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(b) Find AVT of the FET-FET cascade amplifier
Input resistance 1
Output resistance 2
Voltage gain 1
Voltage gain 2
Voltage gain overall
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Example3
(a) Find re of the BJT
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(b) Find gm of the FET
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(c) Find AVT of the BJT-FET cascade amplifier
Input resistance 1
Output resistance 2
Voltage gain 1
Voltage gain 2
Voltage gain overall
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Cascode amplifiers
Cascode amplifiers consists of two or more stages
of the basic BJT and/or FET circuits each of
which utilize single power supply VCC for both
stages
Cascaded amplifiers are used to obtain higher
voltage amplification, or matching of the input
impedance with the transducer and matching the
output impedances with the loading of the
following stage.
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Example4 (page 549 text)
(a) Find re
(b) Find Ro2, Rin, AVT, Ai
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Example4 (page 301 text)
(a) Find VGS and gm of FET
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(b) Find re
(c) Find Ro2, Rin, AVT, Ai
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Darlington pair
DC analysis of the Darlington pair
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AC analysis of the Darlington pair
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(No Transcript)
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Feedback pair
DC analysis of the Feedback pair
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AC analysis of the Feedback pair
Rin of the Feedback pair
Av of the Feedback pair
Ai of the Feedback pair
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Ro of the Feedback pair