Version 4.1
SHEET 1 4480 2500
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FLAG -576 -192 sawtooth
FLAG -624 -272 0
FLAG -1088 -656 0
FLAG 528 224 FET_drive_low
FLAG 928 448 0
FLAG 1568 -32 Vout
FLAG 1024 -32 fet_center
FLAG 832 -576 up_gate
FLAG 816 16 low_gate
FLAG 1408 432 0
FLAG -336 304 0
FLAG -336 96 PWM
FLAG -752 80 control_reference
FLAG 528 -384 FET_drive_high
FLAG -784 320 0
FLAG 1424 224 damper
FLAG -144 -272 osc_pulse
FLAG -192 16 pwm_x2
FLAG 16 224 Q
FLAG 64 192 0
FLAG 400 -240 0
FLAG 416 368 0
FLAG 320 -160 0
FLAG 336 448 0
FLAG -544 32 0
FLAG 1200 192 snub
FLAG -960 -816 Vin
SYMBOL Digital\\srflop -80 96 R0
WINDOW 39 -40 28 Left 2
SYMATTR SpiceLine Vhigh=10
SYMATTR InstName A3
SYMBOL voltage -624 -448 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 -70 130 Left 2
SYMATTR Value PULSE(1 3 0 9.7u 0.1u 0.1u 10u)
SYMATTR InstName V1
SYMBOL Digital\\or 96 64 R0
WINDOW 39 -64 13 Left 2
WINDOW 0 -36 -14 Left 2
SYMATTR SpiceLine Vhigh=10
SYMATTR InstName A4
SYMBOL voltage -464 -544 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 -88 105 Left 2
SYMATTR Value PULSE(0 10 9.85u 10n 10n 0.1u 10u)
SYMATTR InstName V3
SYMBOL bv 640 -368 R0
SYMATTR InstName B3
SYMATTR Value V=V(FET_drive_high)
SYMBOL bv 672 240 R0
SYMATTR InstName B4
SYMATTR Value V=V(FET_drive_low)
SYMBOL res 832 -560 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 5R
SYMBOL res 800 32 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 5R
SYMBOL voltage -1088 -800 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 -41 116 Left 2
SYMATTR Value PULSE(0 48 1u 100u 1u 1E8 2E8)
SYMATTR InstName V4
SYMBOL ind 1264 -48 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName L4
SYMATTR Value 20µ
SYMATTR SpiceLine Rser=10m Rpar=10k
SYMBOL cap 1360 64 R0
SYMATTR InstName C4
SYMATTR Value 20µ
SYMATTR SpiceLine Rser=10m
SYMBOL res 1584 48 R0
SYMATTR InstName R_Load
SYMATTR Value 10R
SYMBOL res 912 -320 R0
SYMATTR InstName R_Isense_up
SYMATTR Value 1m
SYMBOL res 912 240 R0
SYMATTR InstName R_Isense_down
SYMATTR Value 1m
SYMBOL Comparators\\LT1719 -416 32 R0
SYMATTR InstName U3
SYMBOL bv -272 160 R0
SYMATTR InstName B1
SYMATTR Value V=2*V(PWM)
SYMBOL cap 1456 224 R0
SYMATTR InstName C_damp
SYMATTR Value 60µ
SYMBOL res 1456 48 R0
SYMATTR InstName R_damp
SYMATTR Value 100R
SYMBOL voltage -784 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V6
SYMATTR Value SINE(2 0.5 2k)
SYMBOL Digital\\and 432 -368 R0
WINDOW 3 -45 -9 Left 2
SYMATTR Value Vhigh=10
SYMATTR InstName A1
SYMBOL Digital\\and 448 240 R0
WINDOW 3 -40 -9 Left 2
SYMATTR Value Vhigh=10
SYMATTR InstName A2
SYMBOL cap 304 -256 R0
SYMATTR InstName C1
SYMATTR Value 100p
SYMBOL cap 320 352 R0
SYMATTR InstName C2
SYMATTR Value 100p
SYMBOL res 304 -288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res 320 320 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL voltage -544 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 5V
SYMBOL res 1040 32 R0
SYMATTR InstName R3
SYMATTR Value 1Meg
SYMBOL res 912 -656 R0
SYMATTR InstName R4
SYMATTR Value 1m
SYMBOL res 912 -16 R0
SYMATTR InstName R8
SYMATTR Value 1m
SYMBOL nmos 880 -432 R0
SYMATTR InstName M1
SYMATTR Value BSC077N12NS3
SYMBOL nmos 880 128 R0
SYMATTR InstName M2
SYMATTR Value BSC077N12NS3
SYMBOL cap 1136 224 R0
SYMATTR InstName C3
SYMATTR Value 100p
SYMBOL res 1136 48 R0
SYMATTR InstName R9
SYMATTR Value 20R
SYMBOL diode 752 -480 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D1
SYMBOL res 864 -480 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 2R
SYMBOL diode 752 112 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D2
SYMBOL res 864 112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R10
SYMATTR Value 2R
TEXT -576 -584 Left 3 ;oscillator
TEXT -1112 -64 Left 2 !.tran 0 10m 0
TEXT 608 -248 Left 2 ;gate drive isolation\neg pulse transformer
TEXT 640 352 Left 2 ;gate drive isolation\neg pulse transformer
TEXT -1128 -1448 Left 2 ;click on run\nthen click on the "out" net, to plot its voltage waveform\nclick on the plot window, then click on plot settings/add plot pane.\nclick on the net "control_reference"\nclick on the plot window, then click on plot settings/add plot pane.\nthen click on the "sawtooth" net, to plot its voltage waveform\nyou should be able to see how the sinewave covers 50% of the sawtooth amplitude,\nthis represents 50% AM modulation depth.\nclick on the net "control_reference" again to plot it on top of the "sawtooth".\n \nZoom in on the time axis to get half a cycle of V(control_reference)\nclick on the plot window, then click on plot settings/add plot pane\nthen click on the "FET_drive_high" net, to plot its voltage waveform\nclick on the plot window, then click on plot settings/add plot pane\nthen click on the "FET_drive_low" net, to plot its voltage waveform\nclick on the plot window, then click on plot settings/add plot pane\nthen click on the "fet_center" net, to plot its voltage waveform\nnote how the duty cycle of the two FET-drive waveforms and the \n"FET center" node vary with the sine wave.
TEXT -1128 -1488 Left 4 ;Instructions
TEXT -1120 -32 Left 2 !.ic V(P4_Css)=0
TEXT -56 -1448 Left 2 ;This circuit is open loop,, however it would be possible to make it closed loop.\nA DC output power supply would use a DC reference to set the output voltage,\nbut this circuit uses a DC reference with the audio sugnal superimposed on top of it as the reference to set the output voltage\nthis is at net "control_reference".\nthe LC output filter has to have its pole above the max audio freq., but low enough to remove the switching frequency,\nhere it is set at 50k/ (2pie) = 8khz\n \nAs the output is AC, and there is energy storage in the output filter, then under low load, or no load, \nin order to correctly set the output voltage, it will be neccessary to return power to the input power supply.\nIn other words this power supply has to be bidirectional, this power supply is bidirectional because it contains no diodes.\n \nThe 1milliohm resistors in series with the FETs will be their in reality as all wires and PCB tracks have resistance,\nthese components also help the simulation to run.\nSimilarly the snubber and the 1Megohm resistor next to it help the simulation to run. \nand the snubber might actually be their in the real circuit to stop high freq. ringing.\n \nThis power supply does not have isolation, if you want isolation insert it seperately in a the DC voltage supply.... \nsee the block "if you want isolation.." however this isolation power supply would also have to be bidirectional, \nthat is it would have to use synchronous rectification instead of diodes.\n \nThis type of power supply / power amplifier is sometimes used to drive an electric motor.
TEXT -272 -736 Left 4 ;Control circuit \nthis is not a standard control IC
TEXT -576 -1688 Left 5 ;An AM modulated power supply.
TEXT -1096 -536 Left 2 ;if you want isolation \ninsert it here, where \nthe isolation is in a \nstraightforward \nDC-DC SMPS.\nHence none of the problems \nof passing Audio frequencies \nthrough an isolation \ntransformer.\nhowever this isolation power \nsupply would \nwant to use sync rect to \nmake it bidirectional.
TEXT -1104 -1552 Left 4 ;Start off with the "Instructions" section to plot some waveforms, then the rest of the text will make more sense.
TEXT -24 -1480 Left 4 ;Circuit description.
TEXT -1088 -568 Left 4 ;Isolation
TEXT 216 -480 Left 3 ;Pulse shortening
TEXT 224 -448 Left 2 ;to prevent both FETs\nbeing on at the\nsame time.
TEXT -624 -128 Left 3 ;PWM generation
TEXT 968 -744 Left 4 ;Power Circuit
TEXT 1312 -152 Left 3 ;LC output filter\nand damper
TEXT 1120 -144 Left 2 ;Snubber
TEXT -1000 552 Left 2 ;You may republish or reuse this circuit implementation and text providing this line and the following lines are included.\nThis circuit implementation designed by Keith Wallbanks. Originally released on analogsimulation.co.uk\nThis circuit is provided as is without warranty of any kind. This text is intended to implement the MIT licence.
TEXT -872 -1624 Left 4 ;Intended for use as the power supply for an RF oscillator, as a way of generating high power AM.
LINE Normal -848 -816 -848 -592 2
RECTANGLE Normal 576 -768 -704 528 2
RECTANGLE Normal -752 -192 -1136 -592 2
RECTANGLE Normal 496 496 160 -512 2
RECTANGLE Normal -288 -224 -688 -640 2
RECTANGLE Normal -288 176 -640 -96 2
RECTANGLE Normal 1664 496 608 -768 2
RECTANGLE Normal 1552 448 1248 -208 2
RECTANGLE Normal 1216 448 1104 -176 2