Not particularly low distortion 1kHz sine wave oscillator

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Bill Sloman 1 year ago

Edward Rawde has posted a number of low distortion 1kHz sine wave oscillators as LTSpice simulation, and John May has posted a couple of much low distortion examples.

As designs they are bit opaque. I've posted my own attempts.

Here's another.

It doesn't perform all that well. The second harmonic is only 70dB below the fundamental, and te third harmonic only 67dB down.

There are lots of components, but they are all doing exactly what I want them to.

U9 is the core of the oscillator as an inverting Wein bridge. U9 provides the controllable inverting gain that makes the Wein bridge work.

J1 controls the gain. U8 tracks the voltage across J1 so that the gain control voltage on the gate tracks the voltage in the middle of the FET channel. In the circuit posted the gate sits a -4.03V and varies by

16.2mV across the each millisecond of the cycle. The variation includes a 1.94mV 2kHz component which is most positive when the current in the FET channel is highest - +504uA and -504uA. This took some doing.

The mechanism is the rest of the circuit.

U1 is the core of a precise half-wave rectifier. U2 adds the output voltage to this signal to get a full-wave rectified output, which is smoothed by C22 to give about 190mV of mostly 2kHz ripple on top of a

800mV DC signal

This is low pass filtered by a 4-pole Bessel Sallen and Keys active filter around U6 and U7 whose propagation delay was carefully adjusted to get the phase of 2kHz component in the Fet gate drive where I wanted it.

The integrator around U5 compares the DC component in the output of U7 with the 1.250V component coming out of the voltage reference U4 to generate the gain control voltage.

R10 puts a phase advance into the integrator output which stabilises the amplitude control feedback loop.

R27 turns this output into a current which is fed through Q3 into the current mirror formed by Q1 and Q2, to create the gain control voltage across R11 and R21.

It's more complicated than it has to be, but keeps the amplitude control loop out of saturation during start-up.

I've got better distortion levels by largely cancelling the 2kHz in the FET gate control voltage, but that was even messier.

There are better ways of doing it. John May has come up with a mult-phase rectification circuit which is very elegant and gets the distortion levels below 150dB in real life.

I'm postig this mainly as an example of circuit design in action - I've gone as far down a particular rabbit hole as I reasonably can and I am at the point of starting over.

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FerriteBead -224 -1712 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L11 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL res 2592 -1792 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R12 SYMATTR Value 150k SYMBOL res 1376 -1776 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R8 SYMATTR Value 14k SYMBOL res 1216 -1456 R0 SYMATTR InstName R13 SYMATTR Value 56k SYMBOL cap 1312 -1392 R0 SYMATTR InstName C3 SYMATTR Value 15n SYMBOL cap 1056 -1856 R0 SYMATTR InstName C12 SYMATTR Value 15n SYMBOL res 1216 -1568 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R14 SYMATTR Value 11.8k SYMBOL Opamps\\LT1013 1392 -1632 R0 SYMATTR InstName U6 SYMBOL res 896 -1536 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R15 SYMATTR Value 15.8k SYMBOL res 2048 -1840 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R16 SYMATTR Value 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1.2k SYMATTR SpiceLine tol=0.1 SYMBOL FerriteBead -1776 -976 R0 SYMATTR InstName L12 SYMATTR Value 14µ SYMATTR SpiceLine Ipk=3 Rser=0.0122 Rpar=870 Cpar=1000f mfg="Würth Elektronik" pn="7427503 WE-UKW 40060" SYMBOL FerriteBead -1520 -976 R0 SYMATTR InstName L14 SYMATTR Value 14µ SYMATTR SpiceLine Ipk=3 Rser=0.0122 Rpar=870 Cpar=1000f TEXT -1424 -776 Left 2 !.MODEL BAS70L D \n+ IS = 3.22E-9 \n+ N = 1.018 \n+ BV = 77 \n+ IBV = 1.67E-7 \n+ RS = 20.89 \n+ CJO = 1.608E-12 \n+ VJ = 0.3891 \n+ M = 0.3683 \n+ FC = 0.5 \n+ EG = 0.69 \n+ XTI = 2 \n.ENDS TEXT -336 -528 Left 2 ;R2 a,b,c, Vishay Beschlag ACAS06S0830372P1AT precision 10k resistor array \n R1a, R1b Maxim MAX5492LB10000+T 10K resistive divider in a SOT-23-5 package TEXT -720 -464 Left 2 !.MODEL MMBF4391 NJF VTO=-4.6 BETA=0.02779 LAMBDA=0.00595 RD=1 RS=1 IS=1e-14 CGD=14p CGS=10.5p PB=1 B=1 KF=1e-18 AF=1 FC=0.5 mfg=Motorola TEXT -720 -408 Left 2 !.lib LME49710.lib TEXT -1112 -464 Left 2 !.tran 0 10s 0s startup

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Edward Rawde 1 year ago

Are you sure that's the correct circuit Bill?

What I'm seeing has U1 displaced but easy to correct but U2 output is not connected and the feedback from U5 is hanging in mid air above an unconnected current mirror with nothing connected the the FET gate circuit.

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B

Bill Sloman 1 year ago

It probably isn't. Here's much the same circuit tweaked to give the 1kz fundamental closer to 0 dB - 1V rms. The extra componets are R8, R9 and R28 at the top right of the circuit.

Version 4 SHEET 1 3608 920 WIRE -1408 -2176 -1984 -2176 WIRE -1104 -2176 -1408 -2176 WIRE -736 -2176 -1104 -2176 WIRE -320 -2176 -736 -2176 WIRE 208 -2176 -320 -2176 WIRE 336 -2176 208 -2176 WIRE 576 -2176 336 -2176 WIRE -736 -2160 -736 -2176 WIRE 208 -2160 208 -2176 WIRE -320 -2144 -320 -2176 WIRE 3136 -2064 -1776 -2064 WIRE -736 -2032 -736 -2096 WIRE -656 -2032 -736 -2032 WIRE -320 -2032 -320 -2080 WIRE -176 -2032 -320 -2032 WIRE 208 -2016 208 -2096 WIRE 336 -2016 208 -2016 WIRE -320 -2000 -320 -2032 WIRE -736 -1984 -736 -2032 WIRE 336 -1968 336 -2016 WIRE 576 -1968 576 -2176 WIRE 1952 -1920 1744 -1920 WIRE 2160 -1920 1952 -1920 WIRE 1376 -1904 1072 -1904 WIRE 1536 -1904 1376 -1904 WIRE 336 -1888 336 -1904 WIRE -608 -1872 -912 -1872 WIRE -32 -1872 -528 -1872 WIRE 1744 -1872 1744 -1920 WIRE 1072 -1856 1072 -1904 WIRE -1984 -1824 -1984 -2176 WIRE -1776 -1824 -1776 -2064 WIRE 1952 -1824 1904 -1824 WIRE 2160 -1824 2160 -1920 WIRE 2160 -1824 2032 -1824 WIRE -128 -1808 -272 -1808 WIRE -32 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768 -1008 WIRE 64 -784 64 -800 WIRE 368 -784 368 -880 WIRE 368 -784 64 -784 WIRE 576 -720 576 -1168 WIRE 768 -720 768 -736 WIRE 768 -720 576 -720 WIRE -80 -704 -80 -752 WIRE 208 -704 208 -1152 WIRE 208 -704 -80 -704 WIRE 576 -704 576 -720 WIRE 208 -624 208 -640 WIRE 416 -624 208 -624 WIRE 576 -624 576 -640 WIRE 576 -624 416 -624 WIRE 2992 -624 2992 -1360 WIRE 2992 -624 576 -624 FLAG 464 -1152 0 FLAG -48 -1024 0 FLAG -1264 -992 0 FLAG 336 -2176 Vcc FLAG 416 -624 Vee FLAG -560 -1152 0 FLAG 16 -1520 Vout FLAG 2576 -960 0 FLAG -1536 -1520 Fet-gate FLAG 2432 -1456 Vcc FLAG -1040 -832 Vee FLAG -288 -1456 0 FLAG 336 -1888 0 FLAG 1376 -1904 filt1 FLAG 1648 -1648 Vcc FLAG 1632 -1456 Vee FLAG 1520 -1152 0 FLAG 1952 -1920 filter2 FLAG -1616 -1312 0 FLAG 2432 -1584 0 SYMBOL Opamps\\LT1360 208 -1248 R0 SYMATTR InstName U1 SYMBOL res 48 -1344 R0 WINDOW 0 41 37 Left 2 WINDOW 3 36 71 Left 2 SYMATTR InstName R1 SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL res -64 -1152 R0 WINDOW 3 41 74 Left 2 WINDOW 0 43 31 Left 2 SYMATTR Value 4k02 SYMATTR InstName R2 SYMATTR SpiceLine tol=1 SYMBOL cap -160 -1136 R0 SYMATTR InstName C1 SYMATTR Value 3.3n SYMBOL schottky 352 -1344 R0 WINDOW 3 -89 62 Left 2 WINDOW 0 -92 37 Left 2 SYMATTR Value BAS70L SYMATTR InstName D1 SYMBOL schottky 352 -944 R0 WINDOW 3 -78 61 Left 2 WINDOW 0 -81 40 Left 2 SYMATTR Value BAS70L SYMATTR InstName D2 SYMBOL res 352 -1472 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1a SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL res 208 -1536 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 20k SYMATTR SpiceLine tol=1 SYMBOL res 480 -1408 R0 WINDOW 0 41 41 Left 2 WINDOW 3 34 79 Left 2 SYMATTR InstName R2a SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL res 560 -928 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2b SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL res 720 -928 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2c SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL cap 704 -832 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 22n SYMATTR SpiceLine Rser=10 Lser=6n SYMBOL cap 192 -1056 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C4 SYMATTR Value 3.3p SYMBOL res 48 -896 R0 WINDOW 0 39 33 Left 2 WINDOW 3 40 74 Left 2 SYMATTR InstName R1b SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL OpAmps\\opamp2 -176 -1584 R0 WINDOW 3 13 108 Left 2 SYMATTR Value LME49710 SYMATTR InstName U3 SYMATTR SpiceModel LME49710 SYMBOL voltage -1104 -1120 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 12 SYMBOL voltage -1104 -976 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value 12 SYMBOL cap -480 -1552 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C5 SYMATTR Value 15n SYMATTR SpiceLine V=63 Rser=4 Lser=12n SYMBOL res -448 -1520 R270 WINDOW 0 27 56 VTop 2 WINDOW 3 5 56 VBottom 2 SYMATTR InstName R4 SYMATTR Value 10.7k SYMATTR SpiceLine tol=1 SYMBOL cap -64 -1728 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C6 SYMATTR Value 15n SYMATTR SpiceLine V=63 Rser=4 Lser=12n SYMBOL cap 3104 -1664 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C8 SYMATTR Value 100n SYMBOL res 2848 -1760 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R10 SYMATTR Value 68k SYMBOL Opamps\\LT1056A 2992 -1456 R0 SYMATTR InstName U5 SYMBOL cap 2784 -1120 R0 SYMATTR InstName C10 SYMATTR Value 3.3µ SYMBOL cap 2912 -1552 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C11 SYMATTR Value 3.3p SYMBOL res -1600 -1360 R180 WINDOW 0 31 76 Left 2 WINDOW 3 31 40 Left 2 SYMATTR InstName R11 SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL Opamps\\OP27 576 -1264 R0 SYMATTR InstName U2 SYMBOL FerriteBead 576 -672 R0 SYMATTR InstName L2 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL cap 752 -1408 R0 SYMATTR InstName C15 SYMATTR Value 100n SYMBOL cap 752 -800 R0 SYMATTR InstName C16 SYMATTR Value 100n SYMBOL FerriteBead -176 -928 R0 SYMATTR InstName L4 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL cap -336 -2000 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C17 SYMATTR Value 100n SYMBOL cap -336 -1168 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C18 SYMATTR Value 100n SYMBOL res -1632 -1664 R0 WINDOW 0 43 37 Left 2 WINDOW 3 47 73 Left 2 SYMATTR InstName R21 SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL cap 2272 -1184 R0 SYMATTR InstName C21 SYMATTR Value 100n SYMBOL FerriteBead 2288 -1408 R0 SYMATTR InstName L7 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL res -512 -1888 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R22 SYMATTR Value 2.49k SYMATTR SpiceLine tol=1 SYMBOL FerriteBead -320 -2112 R0 SYMATTR InstName L8 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL cap -752 -1984 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C7 SYMATTR Value 100n SYMBOL FerriteBead -736 -2128 R0 SYMATTR InstName L3 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL FerriteBead -656 -896 R0 SYMATTR InstName L9 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL cap -864 -1152 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C23 SYMATTR Value 100n SYMBOL OpAmps\\opamp2 -1408 -1792 M0 WINDOW 3 10 108 Left 2 SYMATTR Value LME49710 SYMATTR InstName U8 SYMATTR SpiceModel LME49710 SYMBOL res -160 -1600 R270 WINDOW 0 27 56 VTop 2 WINDOW 3 5 56 VBottom 2 SYMATTR InstName R26 SYMATTR Value 10.7k SYMATTR SpiceLine tol=1 SYMBOL res -768 -1728 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 4.87k SYMATTR SpiceLine tol=1 SYMBOL cap -784 -1584 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C19 SYMATTR Value 10p SYMBOL FerriteBead 208 -672 R0 SYMATTR InstName L5 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL FerriteBead 208 -2128 R0 SYMATTR InstName L6 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL cap 320 -1968 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C20 SYMATTR Value 100n SYMBOL cap -96 -816 R0 WINDOW 0 -60 15 Left 2 WINDOW 3 -62 54 Left 2 SYMATTR InstName C22 SYMATTR Value 100n SYMBOL njf -1376 -1584 R0 SYMATTR InstName J1 SYMATTR Value MMBF4391 SYMBOL References\\LTC6655-1.25 2560 -1120 R0 SYMATTR InstName U4 SYMBOL OpAmps\\opamp2 -656 -1504 R0 WINDOW 3 13 108 Left 2 SYMATTR Value LME49710 SYMATTR InstName U9 SYMATTR SpiceModel LME49710 SYMBOL res -1200 -1664 R0 WINDOW 0 41 37 Left 2 WINDOW 3 36 71 Left 2 SYMATTR InstName R7 SYMATTR Value 470 SYMATTR SpiceLine tol=0.1 SYMBOL cap -64 -1824 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C9 SYMATTR Value 10p SYMBOL FerriteBead 576 -1936 R0 SYMATTR InstName L13 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL res -944 -1728 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R6 SYMATTR Value 82 SYMATTR SpiceLine tol=1 SYMBOL cap 704 -1088 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C13 SYMATTR Value 10p SYMBOL FerriteBead -1328 -1648 R0 SYMATTR InstName L1 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL FerriteBead 512 -816 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L10 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL FerriteBead -224 -1712 R90 WINDOW 0 -16 0 VBottom 2 SYMATTR InstName L11 SYMATTR Value 1000n SYMATTR SpiceLine Ipk=0.2 Rser=0.562 Rpar=750 Cpar=350f mfg="Würth Elektronik" pn="782422601 WE-CBA 0402" SYMBOL res 2592 -1792 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R12 SYMATTR Value 137k SYMBOL res 1376 -1776 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R8 SYMATTR Value 14k SYMBOL res 1216 -1456 R0 SYMATTR InstName R13 SYMATTR Value 56k SYMBOL cap 1312 -1392 R0 SYMATTR InstName C3 SYMATTR Value 15n SYMBOL cap 1056 -1856 R0 SYMATTR InstName C12 SYMATTR Value 15n SYMBOL res 1216 -1568 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R14 SYMATTR Value 11.8k SYMBOL Opamps\\LT1013 1392 -1632 R0 SYMATTR InstName U6 SYMBOL res 896 -1536 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R15 SYMATTR Value 15.8k SYMBOL res 2048 -1840 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R16 SYMATTR Value 14k SYMBOL cap 1728 -1872 R0 SYMATTR InstName C14 SYMATTR Value 15n SYMBOL res 1888 -1584 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R17 SYMATTR Value 11.8k SYMBOL Opamps\\LT1013 2064 -1648 R0 SYMATTR InstName U7 SYMBOL res 1568 -1552 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R18 SYMATTR Value 15.8k SYMBOL res 1888 -1408 R0 SYMATTR InstName R19 SYMATTR Value 56k SYMBOL cap 1984 -1344 R0 SYMATTR InstName C24 SYMATTR Value 15n SYMBOL npn -1584 -1120 R0 SYMATTR InstName Q1 SYMATTR Value BC847A SYMBOL npn -1712 -1120 M0 SYMATTR InstName Q2 SYMATTR Value BC847A SYMBOL res -1536 -960 R0 WINDOW 0 41 37 Left 2 WINDOW 3 36 71 Left 2 SYMATTR InstName R20 SYMATTR Value 1.2k SYMATTR SpiceLine tol=0.1 SYMBOL res -1792 -960 R0 WINDOW 0 41 37 Left 2 WINDOW 3 36 71 Left 2 SYMATTR InstName R23 SYMATTR Value 1.2k SYMATTR SpiceLine tol=0.1 SYMBOL FerriteBead -1776 -976 R0 SYMATTR InstName L12 SYMATTR Value 14µ SYMATTR SpiceLine Ipk=3 Rser=0.0122 Rpar=870 Cpar=1000f mfg="Würth Elektronik" pn="7427503 WE-UKW 40060" SYMBOL FerriteBead -1520 -976 R0 SYMATTR InstName L14 SYMATTR Value 14µ SYMATTR SpiceLine Ipk=3 Rser=0.0122 Rpar=870 Cpar=1000f SYMBOL res -2000 -1840 R0 WINDOW 0 43 37 Left 2 WINDOW 3 47 73 Left 2 SYMATTR InstName R24 SYMATTR Value 20k SYMATTR SpiceLine tol=0.1 SYMBOL res -2000 -960 R0 WINDOW 0 43 37 Left 2 WINDOW 3 47 73 Left 2 SYMATTR InstName R25 SYMATTR Value 10k SYMATTR SpiceLine tol=0.1 SYMBOL pnp -1840 -1472 M180 SYMATTR InstName Q3 SYMBOL cap -1840 -1376 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C25 SYMATTR Value 100n SYMBOL res -1792 -1840 R0 WINDOW 0 43 37 Left 2 WINDOW 3 47 73 Left 2 SYMATTR InstName R27 SYMATTR Value 6.8k SYMATTR SpiceLine tol=0.1 SYMBOL res 2384 -1792 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R9 SYMATTR Value 17k SYMBOL res 2416 -1728 R0 SYMATTR InstName R28 SYMATTR Value 68k TEXT -1424 -776 Left 2 !.MODEL BAS70L D \n+ IS = 3.22E-9 \n+ N = 1.018 \n+ BV = 77 \n+ IBV = 1.67E-7 \n+ RS = 20.89 \n+ CJO = 1.608E-12 \n+ VJ = 0.3891 \n+ M = 0.3683 \n+ FC = 0.5 \n+ EG = 0.69 \n+ XTI = 2 \n.ENDS TEXT -336 -528 Left 2 ;R2 a,b,c, Vishay Beschlag ACAS06S0830372P1AT precision 10k resistor array \n R1a, R1b Maxim MAX5492LB10000+T 10K resistive divider in a SOT-23-5 package TEXT -720 -464 Left 2 !.MODEL MMBF4391 NJF VTO=-4.6 BETA=0.02779 LAMBDA=0.00595 RD=1 RS=1 IS=1e-14 CGD=14p CGS=10.5p PB=1 B=1 KF=1e-18 AF=1 FC=0.5 mfg=Motorola TEXT -720 -408 Left 2 !.lib LME49710.lib TEXT -1112 -464 Left 2 !.tran 0 10s 0s startup

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E

Edward Rawde 1 year ago

"Bill Sloman" snipped-for-privacy@ieee.org wrote in message news:viot8j$mt28$ snipped-for-privacy@dont-email.me...

Ok I had to adjust the position of U1 and connect the + pin. FFT shows noise at 70dB down.

I decided to find out whether a discrete circuit using a high voltage rail would have better distortion performance. This circuit has no gain control yet but if you take a sample when the output is at about 1V pk-pk you get 100dB down at 2kHz as long as you keep your fingers away from the supply rail. If I could just get rid of 2kHz it would be 130dB down.

Version 4 SHEET 1 2740 1600 WIRE 288 272 224 272 WIRE 464 272 288 272 WIRE 752 272 464 272 WIRE 1136 272 752 272 WIRE 1376 272 1136 272 WIRE 1664 272 1376 272 WIRE 224 320 224 272 WIRE 464 320 464 272 WIRE 1136 320 1136 272 WIRE 1376 320 1376 272 WIRE 752 416 752 272 WIRE 1664 416 1664 272 WIRE 224 464 224 400 WIRE 320 464 224 464 WIRE 464 464 464 400 WIRE 688 464 464 464 WIRE 1136 464 1136 400 WIRE 1232 464 1136 464 WIRE 1376 464 1376 400 WIRE 1600 464 1376 464 WIRE 224 544 224 464 WIRE 320 544 320 464 WIRE 1136 544 1136 464 WIRE 1232 544 1232 464 WIRE 512 624 384 624 WIRE 752 624 752 512 WIRE 752 624 576 624 WIRE 1424 624 1296 624 WIRE 1664 624 1664 512 WIRE 1664 624 1488 624 WIRE -304 656 -304 608 WIRE 464 688 464 464 WIRE 1376 688 1376 464 WIRE 224 736 224 624 WIRE 384 736 384 624 WIRE 384 736 224 736 WIRE 400 736 384 736 WIRE 1136 736 1136 624 WIRE 1296 736 1296 624 WIRE 1296 736 1136 736 WIRE 1312 736 1296 736 WIRE 224 768 224 736 WIRE 1136 768 1136 736 WIRE -304 800 -304 736 WIRE 160 816 80 816 WIRE 320 816 320 608 WIRE 464 816 464 784 WIRE 464 816 320 816 WIRE 1072 816 992 816 WIRE 1232 816 1232 608 WIRE 1376 816 1376 784 WIRE 1376 816 1232 816 WIRE 1664 816 1664 624 WIRE 1840 816 1664 816 WIRE 1952 816 1840 816 WIRE 464 832 464 816 WIRE 1376 832 1376 816 WIRE 752 864 752 624 WIRE 880 864 752 864 WIRE 80 912 80 816 WIRE 128 912 80 912 WIRE 224 912 224 864 WIRE 224 912 192 912 WIRE 992 912 992 816 WIRE 1040 912 992 912 WIRE 1136 912 1136 864 WIRE 1136 912 1104 912 WIRE 224 928 224 912 WIRE 320 928 224 928 WIRE 1136 928 1136 912 WIRE 1232 928 1136 928 WIRE 80 944 80 912 WIRE 464 944 464 912 WIRE 544 944 464 944 WIRE 992 944 992 912 WIRE 1376 944 1376 912 WIRE 1456 944 1376 944 WIRE 224 960 224 928 WIRE 464 960 464 944 WIRE 1136 960 1136 928 WIRE 1376 960 1376 944 WIRE 752 976 752 864 WIRE 752 976 640 976 WIRE 1664 976 1664 816 WIRE 1664 976 1552 976 WIRE 1664 992 1664 976 WIRE 1776 992 1664 992 WIRE 640 1024 640 976 WIRE 1552 1024 1552 976 WIRE 1776 1024 1776 992 WIRE 80 1072 80 1024 WIRE 464 1072 464 1040 WIRE 464 1072 80 1072 WIRE 992 1072 992 1024 WIRE 1376 1072 1376 1040 WIRE 1376 1072 992 1072 WIRE 224 1104 224 1040 WIRE 224 1104 80 1104 WIRE 1136 1104 1136 1040 WIRE 1136 1104 992 1104 WIRE 80 1136 80 1104 WIRE 224 1136 224 1104 WIRE 464 1136 464 1072 WIRE 544 1136 544 944 WIRE 752 1136 752 976 WIRE 992 1136 992 1104 WIRE 1136 1136 1136 1104 WIRE 1376 1136 1376 1072 WIRE 1456 1136 1456 944 WIRE 1664 1136 1664 992 WIRE 80 1248 80 1200 WIRE 80 1248 48 1248 WIRE 224 1248 224 1216 WIRE 224 1248 80 1248 WIRE 464 1248 464 1216 WIRE 464 1248 224 1248 WIRE 544 1248 544 1200 WIRE 544 1248 464 1248 WIRE 752 1248 752 1216 WIRE 752 1248 544 1248 WIRE 992 1248 992 1200 WIRE 992 1248 752 1248 WIRE 1136 1248 1136 1216 WIRE 1136 1248 992 1248 WIRE 1376 1248 1376 1216 WIRE 1376 1248 1136 1248 WIRE 1456 1248 1456 1200 WIRE 1456 1248 1376 1248 WIRE 1664 1248 1664 1216 WIRE 1664 1248 1456 1248 WIRE 48 1264 48 1248 WIRE 320 1328 320 928 WIRE 368 1328 320 1328 WIRE 640 1328 640 1088 WIRE 640 1328 448 1328 WIRE 880 1328 880 864 WIRE 976 1328 880 1328 WIRE 1056 1328 1040 1328 WIRE 1232 1328 1232 928 WIRE 1232 1328 1136 1328 WIRE 1312 1328 1232 1328 WIRE 1360 1328 1312 1328 WIRE 1504 1328 1440 1328 WIRE 1552 1328 1552 1088 WIRE 1552 1328 1504 1328 WIRE 1312 1424 1312 1328 WIRE 1376 1424 1312 1424 WIRE 1504 1424 1504 1328 WIRE 1504 1424 1440 1424 WIRE 320 1520 320 1328 WIRE 688 1520 320 1520 WIRE 1776 1520 1776 1088 WIRE 1776 1520 768 1520 FLAG -304 800 0 FLAG -304 608 V+ FLAG 48 1264 0 FLAG 288 272 V+ FLAG 1840 816 output DATAFLAG 704 624 "round(($)*100)/100" DATAFLAG 512 944 "round(($)*100)/100" DATAFLAG 416 1072 "round(($)*100)/100" DATAFLAG 128 816 "round(($)*100)/100" DATAFLAG 272 928 "round(($)*100)/100" DATAFLAG 176 1104 "round(($)*100)/100" DATAFLAG 272 464 "round(($)*100)/100" DATAFLAG 272 736 "round(($)*100)/100" DATAFLAG 416 816 "round(($)*100)/100" DATAFLAG 512 464 "round(($)*100)/100" DATAFLAG 1616 624 "round(($)*100)/100" DATAFLAG 1424 944 "round(($)*100)/100" DATAFLAG 1328 1072 "round(($)*100)/100" DATAFLAG 1040 816 "round(($)*100)/100" DATAFLAG 1184 928 "round(($)*100)/100" DATAFLAG 1088 1104 "round(($)*100)/100" DATAFLAG 1184 464 "round(($)*100)/100" DATAFLAG 1184 736 "round(($)*100)/100" DATAFLAG 1328 816 "round(($)*100)/100" DATAFLAG 1424 464 "round(($)*100)/100" SYMBOL voltage -304 640 R0 WINDOW 123 0 0 Left 0 WINDOW 39 10 135 Left 2 WINDOW 0 12 7 Left 2 WINDOW 3 15 104 Left 2 SYMATTR InstName V1 SYMATTR Value 96 SYMBOL res 784 1504 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R14 SYMATTR Value 9841 SYMBOL res 208 304 R0 WINDOW 3 36 73 Left 2 SYMATTR Value 47k SYMATTR InstName R10 SYMBOL npn 160 768 R0 SYMATTR InstName Q1 SYMATTR Value BC846B SYMBOL res 208 528 R0 WINDOW 0 -41 35 Left 2 WINDOW 3 -64 67 Left 2 SYMATTR InstName R11 SYMATTR Value 150k SYMBOL npn 688 416 R0 SYMATTR InstName Q2 SYMATTR Value BC846B SYMBOL res 448 304 R0 WINDOW 3 35 73 Left 2 SYMATTR Value 22k SYMATTR InstName R15 SYMBOL npn 400 688 R0 SYMATTR InstName Q3 SYMATTR Value BC846B SYMBOL polcap 304 544 R0 SYMATTR InstName C1 SYMATTR Value 1µ SYMBOL res 208 944 R0 WINDOW 3 35 67 Left 2 SYMATTR Value 470 SYMATTR InstName R16 SYMBOL res 208 1120 R0 WINDOW 3 37 67 Left 2 SYMATTR Value 39k SYMATTR InstName R19 SYMBOL res 64 928 R0 WINDOW 0 -41 40 Left 2 WINDOW 3 -66 68 Left 2 SYMATTR InstName R20 SYMATTR Value 270k SYMBOL cap 192 896 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C6 SYMATTR Value 470p SYMBOL polcap 64 1136 R0 SYMATTR InstName C7 SYMATTR Value 22µ SYMBOL res 736 1120 R0 WINDOW 0 36 38 Left 2 WINDOW 3 36 72 Left 2 SYMATTR InstName R21 SYMATTR Value 3.3k SYMBOL cap 576 608 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C8 SYMATTR Value 10p SYMBOL res 448 944 R0 WINDOW 0 -52 35 Left 2 WINDOW 3 -54 62 Left 2 SYMATTR InstName R22 SYMATTR Value 5.6k SYMBOL res 448 1120 R0 WINDOW 0 -53 28 Left 2 WINDOW 3 -50 58 Left 2 SYMATTR InstName R23 SYMATTR Value 6.8k SYMBOL res 448 816 R0 WINDOW 0 -59 43 Left 2 WINDOW 3 -59 70 Left 2 SYMATTR InstName R24 SYMATTR Value 2.2k SYMBOL res 464 1312 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R25 SYMATTR Value 10k SYMBOL polcap 624 1024 R0 SYMATTR InstName C11 SYMATTR Value 1µ SYMBOL polcap 528 1136 R0 SYMATTR InstName C12 SYMATTR Value 100µ SYMBOL res 1344 1344 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R13 SYMATTR Value 16K SYMBOL res 1152 1312 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R26 SYMATTR Value 8K SYMBOL cap 1376 1440 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName C5 SYMATTR Value 10n SYMBOL cap 1040 1312 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C9 SYMATTR Value 20n SYMBOL res 1120 304 R0 WINDOW 3 36 73 Left 2 SYMATTR Value 47k SYMATTR InstName R29 SYMBOL npn 1072 768 R0 SYMATTR InstName Q4 SYMATTR Value BC846B SYMBOL res 1120 528 R0 WINDOW 0 -41 35 Left 2 WINDOW 3 -64 67 Left 2 SYMATTR InstName R30 SYMATTR Value 150k SYMBOL npn 1600 416 R0 SYMATTR InstName Q5 SYMATTR Value BC846B SYMBOL res 1360 304 R0 WINDOW 3 35 73 Left 2 SYMATTR Value 22k SYMATTR InstName R31 SYMBOL npn 1312 688 R0 SYMATTR InstName Q6 SYMATTR Value BC846B SYMBOL polcap 1216 544 R0 SYMATTR InstName C10 SYMATTR Value 1µ SYMBOL res 1120 944 R0 WINDOW 3 35 67 Left 2 SYMATTR Value 470 SYMATTR InstName R32 SYMBOL res 1120 1120 R0 WINDOW 3 37 67 Left 2 SYMATTR Value 39k SYMATTR InstName R33 SYMBOL res 976 928 R0 WINDOW 0 -41 40 Left 2 WINDOW 3 -66 68 Left 2 SYMATTR InstName R34 SYMATTR Value 270k SYMBOL cap 1104 896 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C13 SYMATTR Value 470p SYMBOL polcap 976 1136 R0 SYMATTR InstName C14 SYMATTR Value 22µ SYMBOL res 1648 1120 R0 WINDOW 0 36 38 Left 2 WINDOW 3 36 72 Left 2 SYMATTR InstName R35 SYMATTR Value 3.3k SYMBOL cap 1488 608 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C15 SYMATTR Value 10p SYMBOL res 1360 944 R0 WINDOW 0 -52 35 Left 2 WINDOW 3 -54 62 Left 2 SYMATTR InstName R36 SYMATTR Value 5.6k SYMBOL res 1360 1120 R0 WINDOW 0 -53 28 Left 2 WINDOW 3 -50 58 Left 2 SYMATTR InstName R37 SYMATTR Value 6.8k SYMBOL res 1360 816 R0 WINDOW 0 -59 43 Left 2 WINDOW 3 -59 70 Left 2 SYMATTR InstName R38 SYMATTR Value 2.2k SYMBOL polcap 1536 1024 R0 SYMATTR InstName C16 SYMATTR Value 1µ SYMBOL polcap 1440 1136 R0 SYMATTR InstName C17 SYMATTR Value 100µ SYMBOL polcap 1760 1024 R0 SYMATTR InstName C2 SYMATTR Value 1µ TEXT -608 1224 Left 2 !.tran 0 4 2.5 1u TEXT -608 1176 Left 2 !.options plotwinsize=0 numdgt=7 method=trap TEXT -408 440 Left 2 ;1kHz low distortion sinewave oscillator. TEXT -400 472 Left 2 ;2 Dec 2024.

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J

john larkin 1 year ago

A good loop gain scheme could use a pair of jfets or mosfets connected antiparallel against ground, gates tied together to the control voltage.

Nonlinearities would mostly cancel.

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Not particularly low distortion 1kHz sine wave oscillator

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