I speak with absolutely zero experience in class D design, so fair warning. But I've done quite a bit of HF/RF/UHF/uWave design as well as some switching power supply design, so not too different, I suspect.
Because of the high frequencies involved in class D amplifier design and the importance of sharp transient control in the switches, it would seem to be advantageous if not critical to design with clad etched printed circuit boards and surface mount components. I've been recently doing some SMT PCB design (analog and logic switching) and found a free PCB design tool that I'd like to give cudos to and to recommend. Check out KiCAD, open-source and free, and pretty dang easy to work with in its new version 5. KiCad EDA
I can pretty safely say that is it the best PCB layout tool I've used, and that includes several stupid-expensive EDA tools I used not too many years ago when I worked at a big defence contractor. KiCAD just makes sense to the way I work, and makes also easy to design and add footprints that might not already be in its libraries. It has some links to SPICE simulators, but I didn't use those so can't comment on that part.
While I'm at it, a great and almost dirt cheap way to get PCB boards fabbed is to email the gerber files to PCBway (China PCB Prototype & Fabrication Manufacturer - PCB Prototype the Easy Way ) -- qty 10 4"x4" double-sided plated-through holes for US$5 plus shipping. Admittedly, the shipping cost goes way above the PC board fab cost, but still $2.20 each for 10 good sized, perfectly printed, silk screened and masked circuit boards received in about a week is nothing to sneeze at. Makes point-to-point wiring no longer an option for me, even if I didn't need the control of SMT patterns.
(No connection with either KiCAD or PCBway, just an impressed user/customer).
Because of the high frequencies involved in class D amplifier design and the importance of sharp transient control in the switches, it would seem to be advantageous if not critical to design with clad etched printed circuit boards and surface mount components. I've been recently doing some SMT PCB design (analog and logic switching) and found a free PCB design tool that I'd like to give cudos to and to recommend. Check out KiCAD, open-source and free, and pretty dang easy to work with in its new version 5. KiCad EDA
I can pretty safely say that is it the best PCB layout tool I've used, and that includes several stupid-expensive EDA tools I used not too many years ago when I worked at a big defence contractor. KiCAD just makes sense to the way I work, and makes also easy to design and add footprints that might not already be in its libraries. It has some links to SPICE simulators, but I didn't use those so can't comment on that part.
While I'm at it, a great and almost dirt cheap way to get PCB boards fabbed is to email the gerber files to PCBway (China PCB Prototype & Fabrication Manufacturer - PCB Prototype the Easy Way ) -- qty 10 4"x4" double-sided plated-through holes for US$5 plus shipping. Admittedly, the shipping cost goes way above the PC board fab cost, but still $2.20 each for 10 good sized, perfectly printed, silk screened and masked circuit boards received in about a week is nothing to sneeze at. Makes point-to-point wiring no longer an option for me, even if I didn't need the control of SMT patterns.
(No connection with either KiCAD or PCBway, just an impressed user/customer).
welcome to the kicad fan club!
class d-pcb layout is indeed critical. I did several pcb layouts with tpa-chips and as a starter recommend all layout hints from ti including their reference designs.
class d-pcb layout is indeed critical. I did several pcb layouts with tpa-chips and as a starter recommend all layout hints from ti including their reference designs.
maybe not too relevant, but I'm using a stereo class D amplifier ATM, bought to drive some exciters (4) for experimental work. The class D amplifiers are built on ordinary pcb's, no covers (just open to the elements) and run off a total of 900uF capacitors per rail. Dynamics are excellent, and are keeping far more expensive amplifiers 'out of the team', ATM.
Good pcbcad software is vital especially those with good error checking.
However, good pcbcad software doesn't make you an expert at layout.
Class d is a minefield. Layout has to be as short and as tigh tas possible.
Decoupling bang up against IC and mosfets.
Mosfet Gate circuit should be very short.
Its taken me years to get better at pcb design and I have made all the rookie mistakes.
Laid out a audio mixer and with the inputs shorted I got 1vRMS of hum on the output !
I had mixed in power supply ground with audio ground. The charging pulses into smoothing capacitors was modulating the audio ground.
Add in a gain of 100 to the hum and the output was swamped.
Dont get me started on valve circuits. Short tracks and careful routing is vital.
However, good pcbcad software doesn't make you an expert at layout.
Class d is a minefield. Layout has to be as short and as tigh tas possible.
Decoupling bang up against IC and mosfets.
Mosfet Gate circuit should be very short.
Its taken me years to get better at pcb design and I have made all the rookie mistakes.
Laid out a audio mixer and with the inputs shorted I got 1vRMS of hum on the output !
I had mixed in power supply ground with audio ground. The charging pulses into smoothing capacitors was modulating the audio ground.
Add in a gain of 100 to the hum and the output was swamped.
Dont get me started on valve circuits. Short tracks and careful routing is vital.
Compared to ss class-d valve circuits work with higher voltages, lower currents and lower bandwidth which makes pcb design much easier.
True, but the much higher impedances involved make noise issues much more likely. A different problem with a similar solution.
I've tried kicad but wasn't able even to add single trace without reading the manual/tutorial. I had a smooth experience with PCAD/ORCAD/Protel/PADS and now with Altium, all of them was more or less intuitive to me but not kicad.
Regarding class D PCB, it is not a big deal at all just remember some formal rules and stay with >=2 layers, better if minimal FR4 thickness.
Regarding class D PCB, it is not a big deal at all just remember some formal rules and stay with >=2 layers, better if minimal FR4 thickness.
I'm sure I was just too lazy investigate kicad and gave it up. Any CAD is ok if you have something to say in PCB 😉 I remember some latvian guy who used CorelDraw to make PCB..
The application notes and white papers at Hypex might be of interest to you. Especially the paper on UcD and EMI.
Can't add a single trace without the tutorial? I designed an entire board using KiCAD without either! You might be trying to use it using the steps of something else perhaps. I had to use PADS for years -- unless it's gotten way, way, WAY(!) better, KiCAD is immensely better IMO.
Oohh, PADS is awful to me as well(I remember I couldn't believe that PADS no way to change keyboard shortcut), I used that only to correct PCB of chinese "engineers". For PCB design I used only PCAD/PROTEL/ALTIUM that's pretty much the same thing, regarding an interface, and doesn't require study in most cases(if you started from PCAD or PROTEL). I heard good feedback about the Eagle(convenient for copy/paste existing design elements) but didn't try yet.
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