Format of Filter Quiz

You will be asked one question about design of a VCVS bandpass
or band-reject filter. Your answer will be based upon reading
the first part of chapter 5 of Horowitz and Hill, and the Matlab
function VCVSfilt3.m. For the quiz you will have access to a computer
running Matlab; you can also refer to any notes you like.

We will set you up individually with a Matlab script template in a folder on the Matlab path. Perhaps a folder like c:\MatlabR12\Work\FiltQuiz123. Your modifications to the script will "self document" your answer. Your script will call function VCVSfilt3 in the solution to your problem, but to begin with will give a wrong answer to your question. By changing cut-off frequencies and how you combine the two sub-filters together you will reach a design that meets specs for the frequency plot you want.

You can go to a c:\MatlabR12\Work\FiltQuiz123 folder and look at examples from years gone by... and run them from the Matlab command line to see how well they meet their frequency specs.

VCVSfilt3 is a Read-Only file that solves for R1=R2, K, and Vout(freq)
when you supply it with a frequency range, center frequency, capacitance,
filter type, filter name, and order. In Matlab type at the command line >>
help VCVSfilt3
to read the documentation about the function.

Examples of questions you may be asked:

Design a maximally flat 2nd order VCVS bandpass filter such that
the gain of the filter is at 8KHz is greater than 0.9 and the attenuation at
1KHz and 40KHz is less than 0.2. Assume that all capacitors are .08 mu-farads
and the the gain setting resistor R in the H&H design is 10K ohms.
Show a semilog plot of amplitude vs frequency for your filter.
Draw out the LP and HP subfilters and how they are connected
to achieve the desired output.

Design a best linear phase band-reject VCVS filter whose response at 6000 Hz
is less than 0.25 and whose gain at 1600 Hz and 18000 Hz is greater than 0.8.
Your answer will be in the form of the resistors needed for the LP and HP
subfilters in your design. Assume that all capacitors are 10^-7 farads
and the the gain setting resistor R in the H&H design is 10K ohms.
Show a semilog amplitude vs frequency plot for your filter.
Draw out the overall circuit for your filter.

In answering the filter quiz you will show a plot that meets the gain criteria and you will draw out a circuit which shows how LP and HP subfilters combine for the final output. Also say what VCVS stands for! You will need to have your copy of selected pages from Chpt 5 of Horowitz & Hill to see the low pass and high pass templates of the VCVS type filter. Redraw the templates with the component values associated with your particular filter quiz.

(2006) IF YOU HAVE TROUBLE MEETING YOUR SPECS FOR CUTOFF MAGNITUDES AT VARIOUS FREQUENCIES CONSIDER INCREASING one FILTER's ORDER FROM 2 TO 4 BY PLACING TWO (IDENTICAL) FILTERS IN SERIES ( Vmag.*Vmag) to sharpen responses. Remember to include UGVF isolation between your two filters in series when drawing out the final design.