I need to build a band pass filter for a receiver circuit I am building but a couple of things have left me scratching my head:
I decided on a 2 back to back 2 pole Sallen Key filters and my supply voltage is 5V DC from the breadboard rail. Mainly due to the simplicity as I am new to electronics and I think it will be adequate for my circuit.
My center frequency is to be 1.2KHz and I would like this to be as narrow as possible but the main purpose of the filter is to remove ambient noise (the input single is from a photo detector - see datasheet TSL 14S-LF).
- My main question is how do I start when choosing my cut-off frequencies?
- would say a 20% either side frequency gap be sensible and realistic (i.e. 1KHz for the high pass and 1.4KHz for the low pass)?
- Does my capacitor and resistor values bear any relevance to the opposite filter or is it all a ratio to itself? (e.g. could I use pf capacitors in 1 and uf capacitors in the other for instance)
I decided on a 2 back to back 2 pole Sallen Key filters and my supply voltage is 5V DC from the breadboard rail. Mainly due to the simplicity as I am new to electronics and I think it will be adequate for my circuit.
My center frequency is to be 1.2KHz and I would like this to be as narrow as possible but the main purpose of the filter is to remove ambient noise (the input single is from a photo detector - see datasheet TSL 14S-LF).
- My main question is how do I start when choosing my cut-off frequencies?
- would say a 20% either side frequency gap be sensible and realistic (i.e. 1KHz for the high pass and 1.4KHz for the low pass)?
- Does my capacitor and resistor values bear any relevance to the opposite filter or is it all a ratio to itself? (e.g. could I use pf capacitors in 1 and uf capacitors in the other for instance)