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 +/- 8 V. Operate the chip at +/- 5 V.

1) Design a 4-pole bandpass filter with, 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.

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

3) 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.

4) 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?

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