Yes, by incorporating a lowpass filter and a highpass filter to create the bandpass. If bandwidth can be any length, how do you keep the center frequency at 2000 Hz?
Hi there orlando,
There are quite a few different ways of doing this filter, so we need to know a little more about what it is you are trying to do and what restrictions might apply as to how you can do it. For example, do you really have to use two separate filters (low pass combined with high pass) or can you use one single filter. Also, can you use an active filter (contains an op amp) or do you have to use passive filter(s) (contains only resistors, capacitors, and possibly inductors)? Another thing we would have to know is what kind of power supply rail(s) you have available, for example do you have plus and minus 15 volts available or not? Also, how selective does your filter have to be?
We have to know these things first to find the best filter for you.
A good example of a modern bandpass filter is the one posted by audioguru, but again we dont know yet if you can use an op amp with your design. The design formulas are as follows:
R1=Q/(G*2*pi*f*C) [input resistor]
R2=Q/((2*Q^2-G)*2*pi*f*C) [one side grounded resistor]
R3=Q/(pi*f*C) [feedback resistor]
where
Q is the desired Q of the circuit (equal to center frequency divided by the bandwidth),
G is the required passband gain,
f is the center frequency (2000 in your case),
C is the capacitance of both C1 and C2 (both caps, for example 0.01uf each).
To use those formulas you pick a value of C say 0.01uf and a value for Q and a value for the passband gain G. Q affects the sharpness of the filter, G affects the gain at 2000Hz.
Since those formulas are for a circuit containing a perfect ideal op amp sometimes you have to adjust the value of f a little bit to get a better circuit for a real life op amp ie making f equal to 2050 would probably get you closer to the actual real circuit for use at 2000Hz. In any case however it's a good idea to do a simulation before deciding on the final values.
Note that the bandwidth is the two sided bandwidth so for example with a center frequency of 2000 and bandwidth of 200 that would mean 100Hz on either side of the center frequency to the -3db point. Since Q=f/bandwidth that means Q=2000/200=10 for this example.