Semiconductors 23

basis of operation for all oscillators

overcome the losses of their feedback resonator circuit

3 main ideal requirements for an oscillator too operate
correctly

1. Regenerative Feedback

2. Initial Trigger

3. av/Av = 1

What type of output signal does a negative feedback produce

180 degrees out of phase with input

Barkhausen criterion states that: Ideally, sustained oscillation
takes place only when

av (attenuation factor)/ Av (voltage gain)= 1

The reduction of the amplitude of a given signal is known as

Attenuation

What are crystals mostly known for

Stability

The Colpitts oscillator with an added capacitor in it's feedback network is known as

Clapp

The functioning of a relaxation oscillator is based upon

Charge/ Discharge

Op-amp based oscillators are usually limited too frequencies below 1 MHz due to what

Too much frequency drift, and unstable

The fundamental frequency of a quartz crystal is determined by the
what?

Physical dimensions

A discrete LC amp that uses a pair of tapped capacitors and an
inductor too produce the regenerative feedback necessary for oscillations is known as a what

Colpitts

most common crystal used in oscillators

quartz

An oscillator that uses a transformer to achieve the 180 degree
voltage phase shift required for oscillation is known as

Armstrong

The negative feedback path in a Wein-bridge oscillator controls

ACL (Closed loop voltage gain)

The key to the operation of a crystal is the what effect

Piezoelectric effect

The circuit diagrams for Colpitts and Hartley oscillators are very
similar. How can they be distinguished

Feedback network uses tapped inductors and a single capacitor

What is an active filter

Tuned op amp

The initial roll off rate for a butterworth filter, compared to a
chebyshev filter is what

Butter worth is relatively flat

A pole is the term used for

RC Circuit

order is used
to identify the number of

Pole Filters

Which type of filter has a relatively flat response across it's pass
band

Butterworth

Of all the oscillator circuits, the most unstable is

Phase shift

A wien-bridge oscillator has two feedback paths

Positive (Non inverting), Negative (inverting)

A filter designed to block all frequencies that fall within it's bandwidth
is called what

Notch

The immunity of a filter to variations in gain when operated near it's
cutoff frequency is called

Damping

A multiple-feedback bandpass filter has two feedback networks which are what

Capacitive, Resistive

What is a pole

RC Circuit

drawback to a butterworth filter

Time delay

In terms of their frequency-response characteristics, what is the
difference between low-pass and high-pass active filter

A low-pass filter allows the lower frequencies to pass through while attenuating the high frequencies. A high-pass filter does the opposite

What is a crossover network

Circuit that splits audio signal

Describe a graphic equalizer

Circuit that lets you adjust amplitude of frequency ranges

What is the oscillator stability

the ability of an oscillator to maintain a consistent, fixed frequency over a given span of time

Why are phase-shift oscillators rarely used

Unstable

What is an oscillator

Circuit that produces a output waveform without an external signal

What is damping

Immunity to variations in gain

A Wien-bridge oscillator produces a total phase-shift of

0-360

n a phase-shift oscillator, the three RC circuits produce a combined
phase shift of what?

180