0195136047.pdf

258 ANALOG BUILDING BLOCKS AND OPERATIONAL AMPLIFIERS

Booster

cylinder

Piston linked to steering

Mechanical

feedback

linkage arm

Fluid path for

one direction

Hydralic

pump

Control

valve

Steering

wheel

Frame

Figure 5.6.1Simplified representation of an automotive power-assisted steering system.

Problems

5.1.1(a) Determine the voltage atAin Figure P5.1.1.

(b) WithVi=10 V,R 1 =10 k,R 2 = 1000 ,

andA=100, find the currenti 2.

5.1.2Consider the circuit configuration shown in Figure

P5.1.2. LetVi=1V,R 1 = 1000 ,R 2 = 2000 ,

andA=3.

(a) Computei 2.

(b) IfR 1 changed to 500, recomputei 2.

5.1.3(a) Findvoutin the circuit shown in Figure P5.1.3.

(b) WithVi=2V,R 1 =R 2 = 2 .5k, R 3 =

5k, andA=100, findvout.

5.1.4Determine the Thévenin resistance viewed from

terminalsA–Bof the circuit of Figure P5.1.4 by

setting independent sources to be zero and apply-

ing a test voltage at terminalsA–B.

*5.1.5Show that any amplifier represented by the model

of Figure 5.1.1 of the text can also be represented

by the more general hybrid model of Figure P5.1.5.

Evaluate the four parameters of the hybrid model

(i.e.,ri,ro,hf,hr) in terms ofRi,Ro, andA.

R 1 R 2

A

i 1 Ai 1

i 2

+

−

Vi

Figure P5.1.1

R 1 v 1 Av 1 R 2 i 2 v 2

+

−

+

−

Vi

+

−

+

−

Figure P5.1.2