| 摘要 |
A differential negative resistance source that provides negative resistance to a differential resonator of a differential VCO. The differential negative resistance source includes first and second active devices, each having first and second current terminals and a control terminal, first and second current sinks, each coupled to a corresponding one of the second current terminals of the first and second active devices, and at least one capacitive device coupled between the second terminals of the first and second active devices. The capacitive device and the separate current sinks form a capacitive degeneration circuit that operates to reduce or otherwise eliminate net differential capacitance at the output of the differential negative resistance source. The capacitive degeneration offsets extra capacitance, which enables an increase of the maximum operating frequency for a given process, and which enables the VCO to be less sensitive to operating conditions.
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