42 lines
813 B
Plaintext
42 lines
813 B
Plaintext
Colpitt's Oscillator Circuit
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* Colpitt is an harmonic oscillator (LC based) which use
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* a capacitive partition of resonator to feed the single
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* active device.
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* Predicted frequency is about 3.30435e+06 Hz.
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* Models:
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.model qnl npn(level=1 bf=80 rb=100 ccs=2pf tf=0.3ns tr=6ns cje=3pf cjc=2pf va=50)
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r1 1 0 1
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q1 2 1 3 qnl
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vcc 4 0 5
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rl 4 2 750
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c1 2 3 500p
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c2 4 3 4500p
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l1 4 2 5uH
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re 3 6 4.65k
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vee 6 0 dc -10 pwl 0 0 1e-9 -10
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.control
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** transient sim
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tran 3n 120u 20u
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plot V(2) v(3)
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** fft of tran sim
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linearize v(3)
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fft v(3)
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let dbv3 = db(v(3))
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plot dbv3 xlimit 1Meg 15Meg
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** measure the frequency of oscillation
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meas sp fosc MAX_AT dbv3 from=1Meg to=5Meg
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** periodic steady state sim
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pss 1e6 50e-6 3 256 10 50 5e-3
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set xbrushwidth=3
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plot v(3) ylimit 0 0.3 xlimit 1Meg 15Meg
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.endc
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.end
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