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US 5,963,084 AGranted
Gm-C cell with two-stage common mode control and current boost
AssigneePhilips Electronics North America Corporation
InventorRudolphe G. Eschauzier
Life of this patent
Estimating the term…
Abstract
A gm-C circuit includes a two-stage common mode control loop to limit the common mode voltage during circuit operation. To prevent latch-up in a cross-coupled differential gm-C type filter, the common mode control loop includes a circuit which provides extra current capability to the common-mode control loop without increasing the quiescent, current. This is accomplished by a current boost technique that provides large amounts of current when needed, while running in a low current mode under normal circumstances.
Claims6
A combination, comprising:
- a first circuit including an input which receives an input signal and an output which outputs an output signal, said first circuit being characterized by the output signal having a voltage ranging between and including a first voltage level and a second, lower voltage level,
- a second circuit for supplying current to said first circuit up to a first current level to maintain the output voltage of said first circuit below said first voltage level when said input signal is below a third voltage level;
- for a given voltage of said input signal, said output voltage of said first circuit increasing with increasing current supplied to said first circuit, and for an input signal at or above said third level, said output voltage being pulled down to said second, lower voltage level when said current supplied by said second circuit is at said first current level;
- and
- a third circuit coupled to said second circuit for providing, in addition to the current of the first current level, to said first circuit only when said input signal has a voltage at or above said third level.
2 more elements
A combination, comprising:
- a first circuit including an input which receives an input signal and an output which outputs an output signal, said first circuit being characterized by the output signal having a voltage ranging between and including a first voltage level and a second, lower voltage level,
- a second circuit for supplying current to said first circuit up to a first current level to maintain the output voltage of said first circuit below said first voltage level when said input signal is below a third voltage level;
- for a given voltage of said input signal, said output voltage of said first circuit increasing with increasing current supplied to said first circuit, and for an input signal at or above said third level, said output voltage being pulled down to said second, lower voltage level when said current supplied by said second circuit is at said first current level;
- and
- a third circuit coupled to said second circuit for providing additional current in addition to the current of the first current level, to said first circuit only when said input signal has a voltage at or above said third level, said third circuit including a current source providing a constant current and boost means, coupled to said current source, which boost means together with the second circuit provides the additional current.
2 more elements
Dependencies are inferred from the claim text.