| 摘要 |
Oscillator circuitry is provided that is based on a ring of inverters. The ring of inverters may be single-ended or differential inverters. Digitally controlled adjustable load capacitors may be provided at inverter outputs to tune the oscillator circuitry. Each digitally controlled adjustable load capacitor may be formed from multiple varactors connected in parallel. Each varactor may have a control input that receives a digital control signal. The digitally controlled adjustable load capacitors in a given oscillator may be adjusted in unison to produce the same capacitance value for each capacitor or may be adjusted individually so that they produce different capacitance values. The inverters may include common-mode-gain reduction features such as series-connected current sources, series-connected resistors, and cross-coupled negative feedback transistors.
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