Chapter 3: Synthesizer Phase Noise 3.1Phase Noise Basics Phase noise is specified in dB referenced to the carrier amplitude (dBc), versus frequency offset from the carrier (fc). In a well-designed oscillator, the noise decreases with increasing frequency offset from the carrier, but the slope of the noise rolloff can be divided into 5 regions, each region governed by a different behaviour and modelled with a different power law. Figure 3.1 illustrates a simple diagram of the various influences on crystal oscillator phase noise. The different mechanisms are described in many papers [163, 164]. Each mechanism is an effect created by the physical properties of the crystal and the active devices in the oscillator circuit. This figure illustrates how different phenomena contribute to the overall phase noise characteristics of an oscillator, each being dominant at different offset frequencies and amplitude levels. The following general remarks about the different power-law noise processes can be stated: 1) Random walk frequency modulation (FM) noise (slope=1/f4) is difficult to measure since it is usually very close to the carrier. Random walk FM usually relates to the oscillator’s physical environment. If random walk FM is a predominant feature of the spectral density plot then mechanical shock, vibration, temperature or other environmental effects may be causing & amp;quot;random & amp;quot; shifts in the carrier frequency. 2) Flicker FM (slope=1/f3) is a noise whose physical cause is usually not fully understood but may typically be related to the physical resonance mechanism of an active oscillator or the design or choice of parts used for the electronics. Flicker FM is common in high-quality oscillators, but may be masked by white FM (1/f2) or flicker PM (1/f) in lower-quality oscillators. I can''t type in the rest here?? can I attach the word doc.