The Ring Oscillator
10 FALL 2019 IEEE SOLID-STATE CIRCUITS MAGAZINE A CIRCUIT FOR ALL SEASONSBehzad RazaviThe Ring OscillatorRRing oscillators are commonly used in many systems because of their wide tuning range, compact layout, and ability to generate multiple phases. These advantages over inductance capacitance (LC) oscillators come at the cost of phase concept of an Oscillator con-sisting of gain stages in a ring can be traced to the vacuum-tube era. For example, in his 1953 patent, Gallay presented the structure shown in Figure 1, where nine triodes form an oscillating loop. The grid (G), cath-ode (C), and anode (A) of a triode can be visualized as the gate, source, and drain, respectively, of a MOSFET. CMOS ring oscillators began to ap-pear in communication circuits in the late 1980s [2], [3].
The thermal-regime phase noise of the first ring is lower primarily be-cause of its greater voltage swings. The ratio of the two oscillators’ sin-gle-ended swings is approximately 35.( / 11dB), close to their FOM dif-ference at 100-MHz offset. The foregoing observations suggest that the choice between the two ring topologies depends on two ...
Download The Ring Oscillator
Information
Domain:
Source:
Link to this page:
Please notify us if you found a problem with this document: