op amp

 shr/p1

FACULTY OF ELECTRICAL & ELECTRONIC ENGINEERING
UNIVERSITI TUN HUSSEIN ONN MALAYSIA
BEL 30403

Operational Amplifier

1)

Design an inverting amplifier with a closed loop gain of AV = -5. Assume the op-amp is driven by a sinusoidal source, vS = 0.1 sin t volts, which has a source resistance of
RS = 1 kΩ and which can supply a maximum current of 5 µA. Assume that frequency
 is low, which means that any frequency effects can be neglected.

2)

An op-amp with a t-network is to be used as a preamplifier for a microphone. The maximum microphone output voltage is 12 mVrms and the microphone has an output resistance of 1 kΩ. The op-amp circuit is to be designed such that the maximum output voltage is 1.2 Vrms. The input amplifier resistance should be faily large, but all resistance values should be less than 500 kΩ.

R2

R3

R1

R4

V1

_
VO
+

3)

Design a summing amplifier to produce a specifiedoutput signal. The output signal generated from a BJT emitter-follower amplifier is vO1 = (5 – 0.5 sin t) V and the effective output resistance is Ro = 50Ω. Design a summing amplifier such that its output sinal is vo = 2 sin  V. One input to the summing amplifier is to be the output of the BJT emitter follower. (Assume that the frequency  goes very low, making the use of a coupling capacitor impractical).

4)

Determine a load current iL in a voltage-to-current conveter circuit as shown. Also find the output voltage vo.
10kΩ
10kΩ
-5 V

_ vo +
1kΩ
1kΩ

shr/1lat_opamp_bel30403 © 2012

100Ω

iL

 shr/p2

5)

Design a difference amplifier with a gain of 30 and minimum differential input resistance ri = 50k .

6)

Determine the range required for resistor R1 to realize a differential gain adjustable from 5 to 500 for the following instrumentation amplifier so that the difference amplifier gain is 2. Assume that resistance R1 is a combination of aa fixed resistance
R1f and a variable resistor