EE 308 - Quiz 2 Prep

Push-pull amplifier uses one npn and one pnp. The dead zone of this amplifier is approximately that many mili-volts:

1.4 mV

High-gain Amplifier consists of two CE stages connected in a cascade - the output of the first feeds the input of the second. Which of these CE stages is more likely to feature emitter degeneration?

2nd one

The load of a CC amplifier is 3 kΩ. If the biased current is 1mA, the maximum output swing (with no clipping) is:

3V

This amplifier type might experience cross-over distortion:

CC (or push-pull, honestly not sure)

This single-transistor amplifier is best characterized as a transconductor:

CE

These single-transistor amplifiers must be cascaded to produce a circuit that behaves as a VoltageControlled-Voltage-Source:

CE-CC

This single-transistor amplifier has Current Gain of approximately unity:

Common Base

This single-transistor amplifier has Voltage Gain of approximately unity:

Common Collector

These single-transistor amplifiers have large (compared to 1/gm) output resistance:

Common Emitter, Common Base

These single-transistor amplifiers have large (compared to 1/gm) input resistance:

Common Emitter, Common Collector

A CMRR can be defined for this type of an amplifier:

Differential Amplifier

To create differential-input transconductor these types of circuits are needed:

Differential amplifier (2 CE's), Current Mirror, CC

Two-stage (Miller) integrator is constructed using: actively-loaded BJT diff. pair with a tail current of 25 µA, a capacitor with value 50pF, and a CE stage. The frequency of the RHP zero is 10-times larger than the unity-gain frequency of the integrator. The bias current of the CE stage is approximately that many µA:

Ibias = 125uA

The differential-input linear range of a BJT differential pair is approximately that many mili-volts:

Lin Range = 26 mV

An op-amp uses two-stage (Miller) integrator. The integrator consists of an actively-loaded BJT diff. pair with a tail current of 25 µA, capacitor with value 50pF, and a CE stage. The slew rate of this opamp is no larger than:

SR <= 0.5V/us

A transconductor is another "name" for this type of a dependent source:

VCCS

The advantage of a push-pull CC over a "regular" CC is:

can source/sink current when requested, not limited by bias current

To construct "Sziklai pair" these type of devices are needed. Mark all that apply.

devices of complementary polarity (1 npn and 1 pnp)

To construct "Darlington pair" these type of devices are needed. Mark all that apply.

devices of same polarity (2 npns or 2 pnps)

Op-amp with GBW of 2MHz implements a non-inverting amplifier with gain of 25 mV/mV. The 3- dB corner frequency of this amplifier is approximately that many kHz

f3dB = 80 kHz

Gm-C integrator is constructed using actively-loaded BJT diff. pair with a tail current of 25 µA and capacitor with value 50pF. The unity-gain frequency of this integrator is approximately that many kHz:

fu = 1.5 MHz

MOSFET-based differential pair has tail current of 100µA; the gate overdrive of each device is 250mV. The transconductance, that relates id to vin(dm), has this approximate value:

gm(MOS) = 0.2 mA/V

It is claimed that an amplifier behaves as a VCVS. This therefore must be true regarding its input and output impedances:

high rin, small rout

The so-called coupling and by-pass capacitors determine this frequency:

lower cut off frequencies

CE amplifier has gm(eff) of 20 mA/V and β of the BJT is 50. The amplifier input resistance is no larger than:

rin <= 2.5k

The load of a CC amplifier is 10 kΩ (>> 1/gm). If the β of the BJT is 100, then the input resistance of the CC circuit must be on the order of:

rin = 1M

CC amplifier drives 10kΩ and exhibits input resistance of 500 kΩ. If a load of 15kΩ is presented, the input resistance of this same CC circuit will become approximately:

rin = 750k

The "small-signal" behavior of a BJT in forward-active, can be characterized by the following resistive quantities: rπ, ro and 1/gm. For any practical device, this one is the largest:

ro

The output resistance of a simple current mirror is 150kΩ. Two resistors of equal value are inserted in the emitters. If the voltage drop over these resistors is 75mV, the output resistance of the modified topology is approximately:

rout(eff) = 583k

These are (some) of the similarities between CE amplifier and CB amplifier:

rout, magnitude of Av (gain)