SMDP Instructional Enhancement Programme: 13-24 Nov. 2006
Nagendra Krishnapura ([email protected]) 13 Nov. 2006
1kΩ
1kΩ 1pF
+ -
Vs +
- Vout
Figure 1:
1. (a) Compute the transfer function Vout(s)/Vin(s) of the circuit in Fig. 1 analytically.
(b) Simulate the circuit from 10 MHz to 10 GHz and plot a) the magnitude and phase response, b) Input referred noise spectral density, c) output noise spectral density.
(c) Find the 3dB bandwidth of the circuit.
(d) Run a transient simulation with a 0.5 V peak sinusoid at the 3 dB bandwidth and plot the output. Are the magnitude and phase consistent with what was computed in (b)?
50fF 25Ω 25Ω 50fF
37.5Ω
port1 port2
Figure 2:
2. Simulate and plot the s-parameters of the circuit in Fig. 2 in a 50Ωsystem.
-0.9V +0.9V
Vpsin(2πfint)
2kΩ 2kΩ
1mA
W/L W/L W/L=10(2.5µ/0.18µ) fin=127MHz
Figure 3:
3. (a) Plot the magnitude and phase response of the circuit in Fig. 3.
(b) Plot the input referred and output noise spectral densities
(c) Simulate the circuit with a 127 MHz si- nusoid with peak values of 50 mV and 200 mV. Take the DFT of the output with 1024 points and determine the 2ndand 3rd harmonic distortion in each case.
L1
L2 C
+ -
vx gmvx +
- Vin
Zin
L1 = 12nH L2 = 4nH C = 0.25pF gm = 3.125mS Iout
Figure 4:
4. (a) Compute the input impedance Zin(s) of the circuit in Fig. 1 analytically. Com- 1
2
pute the frequencyf0 at which the input impedance is real and the input impedance atf0. CalculateIout(s)/Vin(s).
(b) From ac simulations determine the fre- quency at which the input impedance is real, and the input impedance at that fre- quency. Compare the answers with analyt- ical calculations. Simulate the frequency responseIout(s)/Vin(s).
