PWM to Precise DC Voltage?

A

Andrew1

Active member
Joined
May 13, 2008
Messages
1,600
Reaction score
0
Points
36
I need to convert a pulse width signal to a steady DC voltage. The catch is, this voltage will be fed into a voltage-controlled oscillator, so a simple RC filter isn't good enough. I need as little ripple and as fast a transient time as possible. Also, I need it to perform really consistently; i.e., a specific duty cycle must result in an exact voltage, every time. What are my options?
 
first, you have to pick limits. Words like exact voltage, little ripple, fast response are not good enough.

Select some real values, then try to design a multi pole LP filter. You may find that a, say, 4 pole filter will work, or you may find that it's not possible. Then you have to think about changing your requirements.

This is called the design process.

There may be other possibilities. What drives the PWM signal? there may be a DC voltage that is exactly what you need.

Another possibility is to go to the digital domain. Run the PWM signal into a high speed digitizer, then into a fast processor with DSP capabilities, and use that to generate the DC voltage.
 
Back
Top