Fixed Frequency Filter - Low/high pass, 2nd/3rd order Butterworth, Chebychev or Bessel response
This module is a Sallen and Key circuit configuration filter with unity gain in the pass-band. It can be used to realise 3rd order low or high pass filters up to 100kHz, and 2nd order low-pass filters up to 1MHz with appropriate choice of op-amp. When used as a 2nd order low-pass filter, the 1st R-C stage can be used as a 1st order 'roofing' filter to prevent high frequency components getting into the op-amp, which are beyond its capability to suppress. The module can be purchased ready built to the customers own specification.
- Uses a standard SOT23-5 surface mount op-amp, giving a wide and growing choice from low power to high bandwidth/slew rate
- Cascadable to form higher order filters when used as 2nd order building blocks (not recommended beyond 6th order with the Sallen & Key realisation)
- Anti-aliasing filter on its own or in conjunction with a higher order switched capacitor filter e.g. our module based on the LTC 1569, 10th order, low-pass, switched capacitor filter chip
- Reconstruction filter following a digital filter or a switched capacitor filter