Hello!
I am trying to convert a PWM output from a IR sensor to a analog signal. I am measuring temperature change in a system and i need a fast response time (is the us) and a very low voltage ripple : ~1mV. This is not possible with a simple RC circuit, so I was looking into active filters. My PWM signal swings from o to 3V and the period is 1.024ms. I can not increase the PWM frequency. Would the OPA187 work for this application?
Hi Amy,
hhm, I think what you want is impossible. If your signal is PWM then you need to wait at least one full period to get the correct data. So, even with an ideal solution you will have to wait 1.024ms. You cannot get the data earlier. And if you want to do the averaging with analog filters you must accept even much higher settling times. In the following the performance of an active two-pole low pass filter with a ripple of about 1mV is shown. The period of PWM signal is 1.024ms with a duty cycle is 50%:
Please notice the huge settling time of the active low pass filter!
Kai
