Pulse width modulation

ei99dami · Oct 23, 2006

I have problem to make a pwm with high frequency and high resolution. I´m using a internal clock of 160 MHz and I get a pwm of 1.25 MHz and a resolution of 4 bits. I have made my pwm by using a comparator a ROM-table and 2 counters.

How do I do to make a pwm with higher resolution och higher frequency?

How is this made for example for pwm for audio, are they using more outputs to make more resolution?

/Robin

echo47 · Oct 23, 2006

160 MHz to 1.25 MHz is a factor of 128 (7 bits). Why do you have only 4 bits?

Audio outputs commonly use delta-sigma DAC techniques (not simple PWM) to get high amplitude resolution from a modest clock rate. Here's an introduction:
https://www.beis.de/Elektronik/DeltaSigma/DeltaSigma.html

ei99dami · Oct 23, 2006

To create a 4 bit pwm with a compartor to compare a counter with a ROM-table it will be 7 bits lower frequency (if detecting on both falling and rising edge on the clk else it will be 8 bits). Se attachment "pwm_scheme" on the scematic.

I hope it can be done in another way.

I´m going to create a sinus (5-10 MHz) with as high resolution a possible.

My internal clk alternative is max. 500-600 MHz.

It seem that sigma delta modulation is for lower frequency, and by that it is possible to get higher resolution?

/Robin

Pulse width modulation

ei99dami

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echo47

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Pulse width modulation

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