Application Note 948 - Linear Power Amplifier Using Complementary HEXFETs

R7, should that be 100nF or .1uF

martin

Wow, how did you know the value of 4.7 ohms was wrong?

Also I noticed that the amplifier is powered between -Vdd and -Vdd. Now that is unusual... ;-)

And I also noticed that the featured MOSFETs, IRF532 and IRF9532 are not available through mouser. Grr...

Michael

I'm old.

Nah, I always look at the ratio of the feedback resistors on everything...even on my wok

martin

Wait a minute now I'm thoroughly lost. Did you mean C2 should be 100 nF instead of 100 uF? Or R2 should be something else (but surely not in Farads ??? !!! !!! ???) Or that both R2 and C2 are wrong... ???

No, it was a sideway reference to thread Subject: 100nF vs. 0.1uF

but the 4.70R gives the ratio to R6 of 1000:1 ie 60dB, and this is not a mic amp, so 470 is more reasonable. I'm not that good on power amps, but think it could be improved, s/c protection etc.

martin

oh... ha ha ha

The inductor in series with the speaker is for... ???

-MD

wrote in message news: snipped-for-privacy@z72g2000hsb.googlegroups.com...

I can't imagine actually building this amplifier, when you can get a much better one in a single chip package that costs less than 25 cents a watt and has built-in protection circuitry and other goodies. If you really must build a MOSFET amplifier, presumably as a learning experience, I would suggest simulating it first, as I did. I was also able to use all NMOS for the power output stage, by using a PMOS to drive it. The simulation shows flat response 20 Hz to 20 kHz. I have not built it yet, but I think it should work, and the MOSFETs do not seem to be critical. Here it is again:

Paul

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Version 4 SHEET 1 1304 744 WIRE 656 -272 -256 -272 WIRE -416 -208 -672 -208 WIRE -64 -208 -416 -208 WIRE 128 -208 -64 -208 WIRE 480 -208 128 -208 WIRE 128 -160 128 -208 WIRE -64 -144 -64 -208 WIRE 480 -112 480 -208 WIRE -416 -64 -416 -208 WIRE 128 -32 128 -80 WIRE 256 -32 128 -32 WIRE 352 -32 256 -32 WIRE 432 -32 352 -32 WIRE -256 -16 -256 -272 WIRE -256 -16 -320 -16 WIRE -256 16 -256 -16 WIRE -320 32 -320 -16 WIRE 480 64 480 -16 WIRE 656 64 656 -272 WIRE 656 64 480 64 WIRE -672 128 -672 -208 WIRE -64 128 -64 -64 WIRE -64 128 -176 128 WIRE 256 128 256 -32 WIRE 480 144 480 64 WIRE 528 144 480 144 WIRE 624 144 592 144 WIRE 656 144 624 144 WIRE -320 160 -320 96 WIRE -288 160 -320 160 WIRE -256 160 -256 96 WIRE -256 160 -288 160 WIRE -64 176 -64 128 WIRE -16 176 -64 176 WIRE 656 224 656 144 WIRE -112 240 -224 240 WIRE -16 256 -16 176 WIRE 128 288 128 -32 WIRE 256 288 256 192 WIRE 352 288 256 288 WIRE 480 320 480 144 WIRE 480 320 352 320 WIRE -176 336 -176 128 WIRE 256 336 256 288 WIRE 304 336 256 336 WIRE -528 352 -576 352 WIRE -416 352 -416 16 WIRE -416 352 -448 352 WIRE -384 352 -416 352 WIRE -224 352 -224 304 WIRE -224 352 -384 352 WIRE -208 352 -224 352 WIRE 480 352 480 320 WIRE -112 368 -112 240 WIRE -112 368 -144 368 WIRE 32 368 -112 368 WIRE 80 368 32 368 WIRE -288 384 -288 160 WIRE -208 384 -288 384 WIRE 256 400 256 336 WIRE -576 416 -576 352 WIRE -384 416 -384 352 WIRE 32 416 32 368 WIRE 128 416 128 384 WIRE -288 432 -288 384 WIRE 352 432 352 416 WIRE 432 432 352 432 WIRE -64 448 -64 176 WIRE 352 464 352 432 WIRE -672 560 -672 208 WIRE -576 560 -576 496 WIRE -576 560 -672 560 WIRE -384 560 -384 496 WIRE -384 560 -576 560 WIRE -288 560 -288 512 WIRE -288 560 -384 560 WIRE -176 560 -176 400 WIRE -176 560 -288 560 WIRE -64 560 -64 512 WIRE -64 560 -176 560 WIRE -16 560 -16 320 WIRE -16 560 -64 560 WIRE 32 560 32 496 WIRE 32 560 -16 560 WIRE 128 560 128 496 WIRE 128 560 32 560 WIRE 176 560 128 560 WIRE 256 560 256 480 WIRE 256 560 176 560 WIRE 352 560 352 544 WIRE 352 560 256 560 WIRE 480 560 480 448 WIRE 480 560 352 560 WIRE 656 560 656 304 WIRE 656 560 480 560 WIRE 176 608 176 560 FLAG 176 608 0 FLAG -576 352 Vin FLAG 624 144 Vout SYMBOL voltage -672 112 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value 40 SYMBOL voltage -576 400 R0 WINDOW 3 -75 232 Left 0 WINDOW 123 24 44 Left 0 WINDOW 39 0 0 Left 0 SYMATTR Value SINE(0 350m 2000 1u 0 0 5000) SYMATTR Value2 AC 1 SYMATTR InstName V1 SYMBOL nmos 432 -112 R0 SYMATTR InstName M1 SYMATTR Value STD30NF06L SYMBOL nmos 432 352 R0 SYMATTR InstName M2 SYMATTR Value STD30NF06L SYMBOL pmos 304 416 M180 SYMATTR InstName M3 SYMATTR Value IRF7205 SYMBOL res 336 448 R0 SYMATTR InstName R2 SYMATTR Value 1k SYMBOL res 640 208 R0 SYMATTR InstName R8 SYMATTR Value 4 SYMBOL polcap 528 160 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName C3 SYMATTR Value 4700µ SYMATTR Description Capacitor SYMATTR Type cap SYMATTR SpiceLine V=35 Irms=2.03 Rser=0.033 MTBF=2000 Lser=0 mfg="Nichicon" pn="UPR1V472MRH" type="Al electrolytic" ppPkg=1 SYMBOL res 112 -176 R0 SYMATTR InstName R4 SYMATTR Value 2.2k SYMBOL res 240 384 R0 SYMATTR InstName R1 SYMATTR Value 220k SYMBOL diode 336 -32 R0 WINDOW 0 -34 32 Left 0 WINDOW 3 42 35 Left 0 SYMATTR InstName D1 SYMATTR Value 1N4148 SYMBOL diode 336 96 R0 WINDOW 0 -38 -28 Left 0 WINDOW 3 40 35 Left 0 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL diode 336 224 R0 WINDOW 0 -33 28 Left 0 WINDOW 3 39 -30 Left 0 SYMATTR InstName D5 SYMATTR Value 1N4148 SYMBOL res 112 400 R0 SYMATTR InstName R3 SYMATTR Value 100 SYMBOL res 16 400 R0 SYMATTR InstName R6 SYMATTR Value 100k SYMBOL Opamps\\\\LT1037A -176 304 R0 WINDOW 3 9 107 Left 0 SYMATTR InstName U1 SYMBOL res -432 336 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R12 SYMATTR Value 10k SYMBOL zener -48 512 R180 WINDOW 0 24 72 Left 0 WINDOW 3 24 0 Left 0 SYMATTR InstName D6 SYMATTR Value BZX84C15L SYMATTR Description Diode SYMATTR Type diode SYMBOL res -80 -160 R0 SYMATTR InstName R5 SYMATTR Value 4.7k SYMBOL polcap -32 256 R0 SYMATTR InstName C4 SYMATTR Value 100µ SYMATTR Description Capacitor SYMATTR Type cap SYMATTR SpiceLine V=63 Irms=900m Rser=0.1 MTBF=20000 Lser=0 mfg="Nichicon" pn="UPH1J101MRH" type="Al electrolytic" ppPkg=1 SYMBOL res -272 0 R0 SYMATTR InstName R7 SYMATTR Value 100k SYMBOL res -304 416 R0 SYMATTR InstName R9 SYMATTR Value 1k SYMBOL res -400 400 R0 SYMATTR InstName R11 SYMATTR Value 10k SYMBOL res -432 -80 R0 SYMATTR InstName R10 SYMATTR Value 1meg SYMBOL nmos 80 288 R0 WINDOW 3 49 86 Left 0 SYMATTR InstName M4 SYMATTR Value Si4850EY SYMBOL cap -336 32 R0 SYMATTR InstName C1 SYMATTR Value 10p SYMBOL cap -208 304 R180 WINDOW 0 24 64 Left 0 WINDOW 3 24 8 Left 0 SYMATTR InstName C2 SYMATTR Value 5p SYMBOL diode 336 32 R0 WINDOW 0 -33 98 Left 0 WINDOW 3 37 33 Left 0 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL diode 336 160 R0 WINDOW 0 -33 34 Left 0 WINDOW 3 40 94 Left 0 SYMATTR InstName D4 SYMATTR Value 1N4148 SYMBOL cap 240 128 R0 SYMATTR InstName C5 SYMATTR Value 5n TEXT -176 688 Left 0 !.tran .5 TEXT 40 696 Left 0 !;ac oct 5 20 20000

Shouldn't that be written "4R7"?