How does a low pass filter demodulate a pulse width modulated signal? - design of pulse oximeters djvu
I am stuck at home, away from the library of science: (
I need a good explanation or a Web site explaining how to take the pulse width modulated signal (original signal varies in amplitude and frequency) - and demodulated with a low pass.
It was proposed to use an operational amplifier in my filter design. If you have an idea why someone wants to put operational amplifiers in a filter, I wonder, too!
Thanks
Saturday, December 26, 2009
Design Of Pulse Oximeters Djvu How Does A Low Pass Filter Demodulate A Pulse Width Modulated Signal?
1 comment:
I agree with the previous answer. The filter allows to pass the modulated signal to the amplifier, but the company demanded in 20dB/decade above the resonant frequency of the filter falls.
The amplifier uses feedback to improve the filtering and amplify the desired signal with the power supply. Passive devices do not provide amplification.
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