Contents
How is audio produced in a PWM DAC?
The main purpose of this design is to produce audio through a PWM DAC created by the MSP430F5529’s internal Timer Module and external filters. An audio waveform is produced by smoothing the square wave edges created by the PWM signal.
How to amplify a PWM signal with an op amp?
Amplifying a PWM signal with an op amp. Is the slew rate a problem? I need to amplify a PWM signal from 5V to 24V in order to drive a mosfet that in turn drives a small DC motor. The input signal has a frequency of 500Hz and comes from Arduino uno (pin 9).
What is the slew rate of a PWM?
If I use an op amp such as the TL071, the typical slew rate is 16 Volts/microsecond. This means that the op amp will take 24/16 =1.5 micro seconds to reach the high output of the PWM. This seems acceptable to me since with a 500 Hz PWM frequency, the PWM period should be 2000 micro seconds, therefore 1.5 over 2000 is negligible.
How does a PWM convert low level audio to high level?
To achieve AM modulation, the PWM amplifier and filter must produce the proper high-level audio signal. Looking at Figs. 2 and 4, the PWM driver converts the low-level audio to pulses with varying widths. The conversion is easily accomplished with a comparator IC having the audio signal and a triangle wave as inputs.
Is it OK to use 11 bit PWM?
Since the PWM frequency affect the audio quality, then it should be much higher than the sampled audio signal’s frequency. Sometimes it is acceptable to have around 15 KHz audio bandwidth (half of the PWM frequency) with 11-bit resolution. However, it won’t be acceptable in professional audio or recording studio standard.
Why are PWM transmitters used in the radio world?
Pulse Width Modulation (PWM) or Pulse Duration Modulation (PDM) is a technique of converting analog signals into rectangular waveforms. The width of the waveform varies in proportion with the amplitude of the analog signal. PWM solid-state AM transmitters are widely used today thanks to their efficiency, redundancy and reliability.