Oscillator Phase Noise

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What:

Close in noise on the signal generated by the oscillator. Phase noise can be seen as "skirting" if the oscillator tone is looked at on a spectrum analyzer. The final phase noise of an amplifier also depends heavily on the Q of the resonator, with higher Q resonators yielding significantly better results.

Direction:

lower is better. Phase noise is specified in terms of dB down at some distance from the carrier. Be careful that the comparison is being made at the same conditions.

Bipolar Transistors typically offer excellent phase noise performance. Low noise MESFETs typically are about 10 dB higher in phase noise than BJTs, and general purpose FETs may 10 dB higher still.

Range:

80 - 120 dBc/Hz at 100 kHz