V. G. ELLERBRUCH, F. C. FITCHEN AND R, W. SAWREY 
1115 
circuit contour is the boundary between a stable 
or an unstable circuit. 
Now, continuing with our example a crystal 
controlled oscillator was required so the passive 
network at the input must be a crystal. A plot 
for a typical crystal was given in Figure 7, 
curve B, and is repeated in Figure 12 for clar- 
ity. The designer's termination options have 
now been exhausted because the input and out- 
put terminations have both been specified, and 
the difficult task of designing the active circuit 
remains. 
There isn't any step-by-step procedure ap- 
plicable to the design of the active circuit. How- 
Figure 12. — Active and passive circuits combined to make an oscillator, (f = 151.118 MHz) Dashed curves show 
effects of shunt inductor. 
