Page 734 - SUBSEC October 2017_Neat

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02238020/CAPE SPEC/MS/2017

Question 2 KC UK XS

(a) output = V2 = - R2
V1 R1
2
= - 1 000 000 = -10 (1)
10 000

When V1 = 0.5V then V2 = 5V (1)
(b)
(i)
2
f(Hz) Log10f Log10A A
100 2.0 2.00 100
1000 3.0 2.00 100 2
10,000 4.0 1.94 87.0
33,000 4.5 1.75 56.0
100,000 5.0 1.32 20.9

Columns 2 and 4 -- all correct 2UK (-1 for each error)
Column 3 - all correct 2XS (-1 for each error)

(ii)
1

Band width = Range of operating frequencies for the

amplifier (1) OR

Range of frequencies for which the voltage gain does not

fall below a specified fraction of the nominal gain(1)
(iii)

Logarithmic scale more suitable for showing large range of 2
frequencies encountered with op-amps (horizontal scale)(1)

Logarithmic scale more suitable for showing large range of
gains encountered with op-amps OR

amplifiers widely used in audio applications and response of
the ear is logarithmic hence logarithmic gain scale (vertical
(c) scales)(1) 3

Drawing two accurate tangents (2)
(d) Read-off from intersection of tangents (1) 1
(i)

At intersection log10f BW = 4.2 hence BW = antilog104.2 =
15.85 kHz (1) 2
(ii)