grizedale
Advanced Member level 3
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Hi,
Why do Class D amplifier designers prefer high voltage supply rails?
Please find attached here two Full-Bridge , Class D amplifier simulations which run in the free simulator called LTspice by linear.com.
Each simulation is of a 4KHz sine wave which gives 100W of power in the speaker.
One of the Class D amplifiers has an 80V rail and the other has a 40V rail.
Each simulation gives the same output signal (i.e. the same current in the speaker)
……so why do engineers prefer higher voltage rails for Class D amplifiers?……….
……because these simulations show that you can get just the same speaker signal with a lower rail voltage…… and simply using a lower value of filter inductor.
(To run these simulations , you will need to make sure that the text files called “sin” and “sin1” are situated in the same folder as the LTspice simulation files.)
Also, do you know if my representation of the speaker as an 8 Ohm load is correct?…..Does it have an inductance associated with it?…….is this inductance likely to be poorly toleranced.?
The simulation files are in .txt format..........(i had to do this else they wouldnt upload.....anyway, all you need to do to run them in LTspice is save them as .asc files.)
View attachment sin.txt
View attachment sin1.txt
View attachment CLASS D _40V 100W.txt
View attachment CLASS D _80V 100W.txt
Why do Class D amplifier designers prefer high voltage supply rails?
Please find attached here two Full-Bridge , Class D amplifier simulations which run in the free simulator called LTspice by linear.com.
Each simulation is of a 4KHz sine wave which gives 100W of power in the speaker.
One of the Class D amplifiers has an 80V rail and the other has a 40V rail.
Each simulation gives the same output signal (i.e. the same current in the speaker)
……so why do engineers prefer higher voltage rails for Class D amplifiers?……….
……because these simulations show that you can get just the same speaker signal with a lower rail voltage…… and simply using a lower value of filter inductor.
(To run these simulations , you will need to make sure that the text files called “sin” and “sin1” are situated in the same folder as the LTspice simulation files.)
Also, do you know if my representation of the speaker as an 8 Ohm load is correct?…..Does it have an inductance associated with it?…….is this inductance likely to be poorly toleranced.?
The simulation files are in .txt format..........(i had to do this else they wouldnt upload.....anyway, all you need to do to run them in LTspice is save them as .asc files.)
View attachment sin.txt
View attachment sin1.txt
View attachment CLASS D _40V 100W.txt
View attachment CLASS D _80V 100W.txt