Lab 7 - Bandpass Filter
Figure 1 - Bandpass Filter Circuit
For a load resistance of 100 ohms, our tested results did not closely resemble our LTSpice data. We recorded the following for this case:
f-res = 240kHz
f-lo = 108kHz
f-hi = 540kHz
BW = 300kHz
Q = 0.8
When we connected a load resistance of 1k ohm, we noticed a similar resonant frequency, but had dramatically different lo and high frequencies when testing. I believe this may have been caused by temperature variations in different components as time progressed. For this reason, we did not get sufficient data for this test case.
In Lab 7, my group built and tested a bandpass filter that would later be used to filter out unwanted noise in our radio circuit. Shown in Figure 1 to the left, our bandpass circuit proved to be tricky to measure frequency at the output.
During testing in LTSpice, I observed that raising the load resistance produced a narrower bandwidth, and it was also proportional to capacitance.
Figure 2 - Bandpass Filter Circuit Breadboarded