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Oscillator types-wein bridge,colpitts,clapps,hartley,crystal oscillator

The page covers oscillator types viz. wein bridge oscillator,colpitts oscillator,clapps oscillator,Hartley Oscillator and crystal oscillator. They are used in many electronic circuits as reference oscillator in PLL/synthesizer circuits.

wein bridge oscillator

wein bridge oscillator

The figure depicts circuit of wein bridge oscillator using operational amplifier. As shown frequency of oscillation depends on following equation.
f = 1/2*π*(R3*R4*C1*C2)0.5
Where,
If R3=R4=R and C1=C2=C then equation reduced to
f = 1/2*π*R*C

colpitts oscillator

colpitts oscillator

The figure depicts circuit of colpitts oscillator using transistor. As shown frequency of oscillation depends on following equation.
f = 1/2*π* ( L *(C1*C2/C1+C2) )0.5
gm*Rc >= C2/C1

Hartley Oscillator

In the figure-2(colpitts oscillator) above if we replace C1,C2 with L2,L2 and C in place of L then it will become Hartley Oscillator. Frequency of oscillation for Hartley Oscillator is as per following equation.
f = 1/2*π*(C(L1+L2))0.5
gm * RC >= L1/L2

clapps oscillator

In the colpitts oscillator circuit if inductor is replaced by a variable capacitor(say, C3) then frequency of oscillation is expressed as per following equation. The circuit will become clapps oscillator.
f = 1/2*π*(L*C3)0.5
It happens if (C1/C >> 1 ) and (C1/C)>>(C1/C2)

crystal oscillator

crystal oscillator

The figure depicts circuit of crystal oscillator. The series resonance frequency is expressed as,
fs = 1/ 2*π*(L*C)0.5
The parallel resonance frequency is expressed as,
fp = 1/2*π*(L*Ceq)0.5 ,
Where,
Ceq = C*Co/(C+Co)

The frequency of oscillation is chosen between fs and fp. For more refer Quartz Crystal page.

RELATED LINKS

crystal oscillator manufacturers
crystal oscillator vs frequency synthesizer
OCXO vs VCXO vs TCXO vs DCXO
What is Quartz Crystal

RF and Wireless Terminologies


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