I have designed the attached circuit for detecting how long an ultrasonic pulse need to to travel a distance. the input signal is going to be from a 40 k ultrasonic receiver. First stage is 40k Band pass - 1k pass band - differential MFB filter with a gain of 2.25dB at Center frequency. In feedback path of differential amplifier I have used 33k instead of ideal value of 31.6k . I will appreciate some useful comments on how this circuit can be improved. Also I am going to design a PCB using smt components. I need suggestion to improve the circuit like adding capacitor to supply rail and VOCM which will reduce power supply noise etc.
regards
Ajit Singh