Fig.18 Frequency stability of the VCO as a function of ambient temperature with supply voltage as a parameter.

 without offset (R2 = ∞): (a) R1 = 3 kΩ; (b) R1 = 10 kΩ; (c) R1 = 300 kΩ.

−−− with offset

(R1 =

∞): (a) R2 = 3 kΩ; (b) R2 = 10 kΩ; (c) R2 = 300 kΩ.

In (b), the frequency stability for R1 = R2 = 10 k

Ω at 5 V is also given (curve A). This curve is set by the total VCO bias current, and is

not simply the addition of the two 10 k

To obtain optimum temperature stability, C1 must be as small as possible but larger than 100 pF.

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