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\begin{center} 
{\bf EE 322 } \\[.1in]
{\large \bf Lab 11:  Switched Capacitor Filters}
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In this lab we will use the Linear Technology LTC1060 (almost the same as
the Maxim MF10) Universal Dual Switched-Capacitor Filter to implement a
4-pole bandpass filter.  As usual, it will be advantageous to start the
filter design before coming to lab.

NOTE:  The LTC1060 has a maximum supply voltage of $\pm$~8~V.  Operate
the chip at $\pm$~5~V.  Adjust the supply voltages on your breadboard
now, and readjust back to $\pm$~15~V at the end of the lab.

\begin{enumerate}
\item Design a 4-pole Chebyshev type I bandpass filter with 2~dB ripple
in the passband, having a $Q$ of 25, a center frequency of 2~kHz, and a
gain in the pass band of 1.  Use the configuration of Mode~3 of the
filter, which is useful for cascading.  Design the filter by starting
with a normalized two-pole Chebyshev lowpass filter, and transforming
to a bandpass by making the substitution

$$s_n = \frac{s^2 + \omega_o^2}{Bs}$$

where $Q = \omega_o/B$.  Convert this 4th order filter to a cascade of
two second-order bandpass filters.  

\item Build the 4th order filter by cascading two 2nd-order bandpass
filters built using Mode~3 of the LTC1060.  

\item The first filter block has a low-pass, high-pass and band-pass
output.  Verify the operation of these three outputs for frequency
inputs in the range of 0 to 20~kHz.  Now look at the outputs for
frequencies around 200~kHz, 400~kHz, etc.

\item Measure the frequency response, gain and bandwidth of the 4-pole
bandpass filter and compare with the desired values.  Plot amplitude
and phase.  What happens to the phase as you go through the passband?

\item Look at the step response of the bandpass filter.  Comment.

\item Change the center frequency to 1~kHz by changing the clock
frequency.  What should the bandwidth of the filter be now?

\end{enumerate}

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