Switch linearized track and hold circuit for switch linearization
AssigneeThe Regents of the University of California
InventorBang-Sup Song
Life of this patent
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Abstract
Circuits that provide a gate boost to address non-linear threshold voltage variation in a CMOS T/H circuit. In embodiments of the invention, a boost capacitor and a feedback amplifier add a signal-dependent threshold voltage to the switch gate over-drive voltage of a switch that controls track and hold circuit sampling. In a modified embodiment, capacitive boost is omitted and the feedback amplifier provides the signal-dependent threshold voltage boost. In another embodiment, a boost capacitor and a diode connected transistor provide the signal-dependent threshold voltage boost. In a modified embodiment, capacitive boost is omitted and the diode connected transistor provides the signal-dependent threshold voltage.
Claims10
A differential track and hold circuit, each half of the differential track and hold circuit comprising:
- a sampling capacitor for holding a positive or negative version of an input voltage to be sampled;
- a switch for providing the positive or negative version of the input voltage to the sampling capacitor, such that when the switch is turned off, the sampling capacitor holds the voltage delivered to it by the switch just before the switch is turned off;
- a driver to control the switch;
- a buffer amplifier to output a sampled voltage held by the sampling capacitor;
- and
- means for reducing switch non-linearity in the switch by adding a signal-dependent threshold voltage to a gate over-drive voltage of the switch such that the on-resistance and the channel charge injection of said switch is made linear and independent of the input voltage.
Dependencies are inferred from the claim text.