EE2500 / EE2514 Resit coursework part A Analogue Electronics,
Aug 2015
(a) (i) Which region is the transistor in Figure Q1(a) operating
in? [1 mark]
(ii) Design the circuit in Figure Q1(a) to obtain a current ID
of 80 Find the value required for R and find the dc voltage VD. Let
the NMOS transistor have Vth = 0.6V, nCox = 200 A/V2, L = 0.8 m and
W = 4 m. Neglect the channel-length modulation effect (i.e. = 0).
[3 marks]
+1.8V
R
VD
ID
Figure Q1(a)
(b) The NMOS and PMOS transistors in the circuit of Figure Q1(b)
are matched with kn
= kp = 1mA/V2 (where kx = xCoxW/L) and Vthn = Vthp = 1V.
Assuming = 0 for
both devices, find the drain currents iDn and iDp as well as the
voltage vo for:
(i) vi = 0 V [4 marks] (ii) vi = +2.5 V [4 marks] (iii) vi =
-2.5 V [2 marks]
10k
2.5V
-2.5V
vi vo
iDp
iDn
QP
QN
Figure Q1(b)
(c) Draw an inverting amplifier with two separate input
resistors connected to two different input voltages V1 and V2.
Write the output expression for the circuit,
assuming all resistor values are equal to R. What is this
circuit typically called?
[3 marks]
(d) (i) If a single input amplifier with a closed-loop gain |G|
= 50 and a non-feedback
resistor equal to 1 k is needed to amplify a signal from a
grounded voltage source
with an output impedance of 2 k, would you choose an inverting
amplifier or a
non-inverting amplifier design? Why? What is the input impedance
of the other
amplifier? [2 marks]
(ii) What should be the value of the feedback resistor in each
case? How would you
implement it (approximately) using resistor values from the
E24
