Eduqas A-Level Electronics Analogue systems overview quiz quiz

$+10$

$+11$

$-10$

$-11$

$+9$

$-9$

$-10$

$+10$

Approximately 0 V

The supply voltage

Half the supply

The input voltage

$0$

$+1$

$-1$

Infinite

$1.0\ \text{kHz}$

$340\ \text{Hz}$

$3.4\ \text{kHz}$

$34\ \text{kHz}$

It needs no power supply

It uses larger inductors

It always has a lower cut-off frequency

It can provide gain in the pass band

A comparator uses no (or positive) feedback and saturates to a rail; an amplifier uses negative feedback for a linear gain

A comparator uses heavy negative feedback for a precise linear gain; an amplifier instead runs open-loop and saturates hard to one of the supply rails

They are exactly the same circuit, just drawn and labelled differently on the schematic

An amplifier always runs from a much higher supply voltage than a comparator ever does

A much higher open-loop voltage gain than an ordinary plain comparator

Two switching thresholds that prevent chatter on noisy signals

A noticeably lower power consumption for the whole circuit

A smooth, fully linear output that follows the input voltage

The supply voltage

Half the supply

Zero

The sensor voltage

It amplifies the large common-mode level along with the small signal

It rectifies the bridge output signal before amplifying it

It has the lowest possible voltage gain of any op-amp circuit

It amplifies the difference signal while rejecting common-mode noise

Crossover distortion at the zero-crossing

Very low power efficiency compared with a Class A stage

It is completely unable to drive a loudspeaker load

It provides no voltage gain to the input signal at all

$8.0\ \text{V}$

$2.8\ \text{V}$

$0.5\ \text{V}$

$5.7\ \text{V}$