CC and CB amplifiers The dc current gain of an emitter follower is: 0 1 dc Dependent on r'e The output voltage of an emitter follower is:

CC and CB amplifiers

• The dc current gain of an emitter follower is:
• 0
• 1
• ßdc
• Dependent on r'e

• The output voltage of an emitter follower is:
• In phase with vin
• Much greater than vin
• 180˚ out of phase
• Generally much less than vin

• An emitter-follower buffer is generally used when:
• RG << RL
• RG = RL
• RL << RG
• RL is very large

• For maximum power transfer, a CC amplifier is designed so:
• RG << zin
• zout >> RL
• zout << RL
• zout = RL

• If a CE stage is directly coupled to an emitter follower:
• Low and high frequencies will be passed
• Only high frequencies will be passed
• High-frequency signals will be blocked
• Low-frequency signals will be blocked

• An emitter follower circuit always makes the source resistance
• ß times smaller
• ß times larger
• Equal to the load
• Zero

• The amplifier configuration that produces a 180˚ phase shift is the:
• CB
• CC
• CE
• All of the above

• The ac emitter resistance of an emitter follower
• Equals the dc emitter resistance
• Is larger than the load resistance
• Is ß times smaller than the load resistance
• Is usually less than the load resistance

• A common-base amplifier has a voltage gain that is
• Much less than one
• Approximately equal to one
• Greater than one
• Zero

• An application of a common-base amplifier is when:
• Rsource >> RL
• Rsource << RL
• A high current gain is required
• High frequencies need to be blocked

• A common-base amplifier can be used when
• Matching low to high impedances
• A voltage gain without a current gain is required
• A high-frequency amplifier is needed
• All of the above

Frequency Effects

• In a BJT amplifier circuit, C'e is the same as
• Cbe
• Cib
• Cibo
• Any of the above

• In a BJT amplifier circuit, increasing the value of Cin and Cout will:
• Decrease at low Av at low frequencies
• Increase Av at low frequencies
• Decrease Av at high frequencies
• Increase Av at high frequencies

• Input coupling capacitors in FET circtuis
• Are normally larger than in BJT circuits
• Determine the high-frequency cutoff value
• Are normally smaller than in BJT circuits
• Are treated as ac opens

• On FET data sheets, Coss is
• Equal to Cds + Cgd
• Equal to Cgs - Crss
• Equal to Cgd
• Equal to Ciss - Crss