ELEC 320, Fall 2006
Prof. Rich Kozick

## Homework 4

Date Assigned: Monday, September 4, 2006
Date Due: Wednesday, September 6, 2006 (Homework 3 is also due on this day)

1. Reading: Please continue to study Chapter 1 in the Lathi text. Pay special attention to the following: what is a signal, what is a system, continuous-time versus discrete-time, and what does it mean for a system to be linear, time-invariant, and causal.

2. Suppose you need to design a filter for a voltage signal that has the form

v(t) = 0.05 cos(200 t) + 10 cos (20,000 t) volts

The signal component at frequency 200 rad/s is the desired signal, while the component at 20,000 rad/s is an undesired interference signal. The filter should pass the 200 rad/s component with near unity gain, and the interference at 20,000 rad/s should be attenuated by the filter so that its amplitude is at least 10 times smaller than the desired signal amplitude.
What order filter is required to achieve this? Explain your reasoning.

3. (a) Specify a circuit that performs as a band-stop filter. You do not have to analyze the cutoff frequency or do a full Bode plot, but explain why it operates as a band-stop filter.

(b) For each filter given in Problem 5 of Homework 3, review the filter type (low-pass, high-pass, band-pass, or band-stop) and determine the filter order (first-order or second-order).