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CACD Group updated 2000.03.30 Author Janez Puhan |
Multiple Waveform GeneratorThe circuitThe circuit generates a triangle and sine signal. It comprises a comparator, an integrator and a JFET. The opamp x1 (comparator) compares the square and triangle signal. Whenever the node 1 voltage reaches zero, x1 switches its output. This causes the integration capacitor to be charged in the opposite direction until the comparator senses zero voltage again. The oscillation frequency depends on the time constant of the integrator (r2 and c1) and its hytheresis (r1 and r3). The triangle signal is converted to sine using a JFET. The harmonic distortion is minimal (1%) when the amplitude of v(4) is 3.5V.
The input file (multiple_waveform_generator.cir)multiple waveform generator * frequency fo = 1 / (4 r2 r3 c1 / r1) .control tran 2us 170ms 120ms plot v(2) 4*v(4) 10*v(7) xlabel t[s] ylabel 'v(2) v(4) v(7) [V]' + title 'TRAN analysis' .endc x1 0 1 2 opamp x2 3 0 4 opamp r1 2 1 43k r2 2 3 10k r3 4 1 10k r4 4 5 1meg r5 5 0 1meg r6 4 6 100 r7 7 0 100 c1 3 4 1uF d1 4 5 dn4148 d2 0 5 dn4148 j1 7 5 6 jn3820 .subckt opamp 1 2 3 v1 5 0 dc 15V v2 6 0 dc -15V c0 2 0 1nF e1 4 0 2 1 -100k m1 3 4 5 5 pkanal w=100u l=10u m2 3 4 6 6 nkanal w=100u l=10u .model pkanal pmos .model nkanal nmos .ends .model dn4148 d (rs=0.8 cjo=4pF is=7e-09 n=2 vj=0.6V tt=6e-09 mj=0.45 bv=100V) .model jn3820 pjf (beta=1.27m lambda=40m vt0=-2.5V) .end The Results |
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