[Electronic Competition] Adjustable cutoff low-pass filter, based on LTC1569

The LTC1569-7 is a 10th-order low-pass filter with linear phase and root-raised cosine magnitude response. The LTC1569-7's high selectivity combined with its linear phase in the passband makes it suitable for filtering in data communications and data acquisition systems. Unlike other LTC series that require clock signal control, the LTC1569-7 is easy to use, and the screenshot size can be controlled using the peripheral resistor value. I have tried the verification board and found that the transition zone is very narrow and the effect is good.

The disadvantage is that it can only be used as a low-pass filter, and the power supply voltage is too small, causing the filter itself to be unable to handle signals with excessive amplitude; the adder in the front stage is used to add DC bias to prevent distortion of the output signal. DC bias and cutoff frequency are adjusted through potentiometers.

The reference circuit diagram and its cutoff frequency calculation formula are as follows: