RF Systems Lab
Lab 7: Bandpass Filter
Lab 7 Goals:
Introduce the tank circuit as a bandpass filter
Become familiar with bandwidth and Q of a resonant circuit
Analyze the filter with LTspice
Breadboard and test filters
Lab 7 Equipment:
AFG1062 Arbitrary Function Generator
Tektronix MDO 3032 Oscilloscope
Omega HHM90 Digital Multimeter
USB Device
1/2 Watt 8 Ohm Speaker
7.1 The Tank Circuit
A simple and very useful bandpass filter is termed a tank circuit. The parallel inductor and capacitor combination will store energy at a resonance frequency, hence the term tank (storage tank). The pre-lab report for chapter 7 can be found below.
PreLab_7.pdf7.1 Filter Construction
The circuit is assembled with both the source and load resistances having a value of 100Ω. Then, the signal generator is used to provide a variable frequency input signal. While constant amplitude is maintained, the resonant frequency and resonant Q are found. Then, the measurements are repeated with load and source resistance changed to 1kΩ. These results are recorded in Table 1.
Figure 1: Circuit Measurements at 100Ω and 1kΩ