The Class D RF amplifier - Design and calculations (2/3)
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- Опубликовано: 28 окт 2022
- #174 In this video I continue the series on the Class D amplifier by designing such a circuit. I go for the most basic voltage switching amplifier, but as always I still need some sort of output matching since that is the only way to get the desired output power. In the end I simulate the circuit and hopefully the real thing will behave in a similar fashion.
Related videos:
Class A amplifier part 1 - • The Class A amplifier ...
Class A amplifier part 2 - • The Class A amplifier ...
Class B amplifier part 1 - • The Class B amplifier ...
Class B amplifier part 2a - • The Class B amplifier ...
Class B amplifier part 2b - • The Class B amplifier ...
Class C amplifier part 1 - • The RF Class C amplifi...
Class C amplifier part 2 - • The RF Class C amplifi...
Class D audio amplifier part 1 - • The Class D audio ampl...
Class D audio amplifier part 2 - • The Class D audio ampl...
Class D audio amplifier part 3 - • The Class D audio ampl...
Class D RF amplifier part 1 - • The Class D RF amplif...
Class D RF amplifier part 2 - • The Class D RF amplifi...
Used datasheets:
www.onsemi.com/pdf/datasheet/...
www.ti.com/lit/an/scaa035b/sc...
Further reading and matching calculator:
rfic.eecs.berkeley.edu/ee242/p...
home.sandiego.edu/~ekim/e194r...
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Two the highest quality, most information-dense electronics channels/people on RUclips today: Sam Ben-Yaakov & You!! Thank You, dude! Especially for LTSpice videos.
Found this channel recently and have learned so much about electronics. Thanks for the great content!
Nice work.
I think there’s a maximum of 50mA for the whole IC, a rating for the Vcc or GND pin. I’d just put a single-stage BJT totem pole (or sziklai pair totem pole) after a CMOS output, pretty simple and you won’t be fretting about the 0.6V drop on either end at only half a watt.
Gate driver ICs like the IR2184 are really handy to have too, I’d get half a dozen. Don’t buy FETs without them.
Make it into an FM/FSK transmitter using a 4046 on either end, I think they can do 5MHz.
IR2184 is much too slow for a 5MHz amplifier.
I think the 74AC14 datasheet states as absolute maximum a DC supply current of 50mA per output; but I guess they never intended this sort of usecase so a clear global value is not given.
I just noticed, in the SN74AC14 (Texas Instruments) datasheet, there is a global 200mA value for continuous DC.
@@alainblazit9504 Oh yeah, the fixed dead-time of 500ns. The 21844 would probably work.
@@FesZElectronics I’d test it with some resistors if you have a 74X14 lying about, it’s probably close enough.
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This is push-pull Class C, not Class D. Also, computing the matching networks becomes much easier if you use the complex impedance representations. (jωC, 1/jωL, etc)
do it now with 25W to really demonstrate how small the heatsink can remain compared to a class AB or even a class C amplifier
Is there are special reason why you dodnt go with the normal drivers? Or simply use a buffer IC as the driver? (there is also the BJT option.....).
Also since those were SMD parts i assume you are making a PCB. There is also the option of using 4 ICs in order to increase the max current in case you need more
I'm building this circuit just as an experiment to highlight how it works, I don't plan on using the amplifier for any other purpose. I could have gone with a buffer IC, that sound like a really good alternative, but I already had these inverting gates around so I decided to use them.
@@FesZElectronics THX that is a good explanation .
PS are u making the PCB at home or using a fab like JLC?
I wonder why, dead time? /
Upd: oh now I can see, never mind 🙃 I was wrong. I thought you want to use it as a driver.