ABSTRACT
Phase noise is created by the time jitter of zero crossings of the generated sine wave. The local oscillator phase noise spectrum mixes adjacent channel interfering signals at some offset frequency into the Intermediate Frequency passband. The interfering signal then shows up as a noisy replica, reducing the signal-to-noise ratio. Reciprocal mixing is often a major limitation to the useable dynamic range of a receiver. Phase noise has no restoring mechanism so must be dealt with by design or feedback. The active device and any post-amplifiers also contribute to a noise floor. Noise sensitivity depends on the specific time at which the noise pulse occurs. An integrated transformer can be used to couple multiple identical oscillators. Harmonic balance simulation in ADS can be used for oscillator phase noise analysis. One can also enable nonlinear noise simulation in order to mix small-signal noise sources with the oscillator fundamental and harmonics.
