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US 4,366,455 AGranted
Switched-capacity amplifier, switched-capacity filter and charge-transfer filter comprising such an amplifier
AssigneeThomson-CSF
InventorJean L. Berger
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AssigneeThomson-CSF
InventorJean L. Berger
Estimating the term…
A switched-capacity amplifier formed from integrated capacities has undesirable parasitic capacities that are large and variable on only one terminal of each of the capacities. A voltage-follower stage is connected to this terminal of each of the capacities (except those capacities which are grounded) to offset the parasitic capacity. The amplifier is also connected in a switched-capacity filter and a charge-transfer filter.
A circuit having a plurality of integrated capacities comprising
A switched capacity filter having a plurality of integrated capacities comprising
A change transfer filter having a plurality of integrated capacities comprising
A circuit having a plurality of integrated capacities comprising
Dependencies are inferred from the claim text.
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Networks using time-varying elements, e.g. N-path filters: switched capacitor networks
Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements: using switched capacitors, e.g. dynamic amplifiers;…
Impedance networks
Amplifiers
Term ended 5 Nov 2000 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The present invention relates to a switched-capacity amplifier.
It also relates to switched-capacity filters and to charge-transfer filters comprising such an amplifier.
An amplifier is known which comprises essentially n capacities periodically switched in parallel and in series; the same voltage charges simultaneously the n capacities which are switched in parallel; an amplified voltage is obtained between the end terminals A and B of the n capacities which are switched in series. The periodic switching of the n capacities in parallel and in series is achieved by means of MOS transistors operating as switches. Finally, the n capacities and the transistors are integrated on the same semiconductor substrate which is generally silicon.
Other aims, characteristics and results of the invention will become clear from the following description, given by way of non-limiting example and illustrated by the accompanying figures which represent:
FIG. 1, a sectional view of an integrated capacity with counterbalancing of the parasite capacity C.sub.P1 ;
FIG. 2, a switched-capacity amplifier in accordance with the present invention
In the different figures, the same reference numbers designate the same elements but, for the sake of clarity, the sizes and proportions of the different elements have not been respected.
FIG. 1 shows a sectional view of an integrated capacity with compensation for the parasite capacity C.sub.P1. As was seen above, the capacity is formed by a technology which comprises a silica layer 2 covering the semiconductor substrate 1 which is generally silicon, of type P in the example. Two levels of polycrystalline silicon N.sub.1 and N.sub.2 are integrated in the layer of silica and disposed parallel to the substrate. On the silica layer is deposited a layer of aluminium comprising two parts n1 and n2 insulated from each other by the silica. Each plate of the integrated capacity is formed by part of the aluminium layer connected to one of the polycrystalline silicon layers. We will call B.sub.1 the terminal of the integrated capacity which is connected to the plate of the capacity comprising the lower level N.sub.1 of polycrystalline silicon and B.sub.2 the terminal of the integrated capacity which is connected to the plate of the capacity comprising the upper layer N.sub.2 of polycrystalline silicon.
The silica layers separating the different metalizations are thin compared to the silica layer separating them from the substrate. The presence of the semiconductor substrate 1, carrying the oxide layer 2, which is generally taken as reference for the potentials, introduces a parasite capacity C.sub.P1 and C.sub.P2 on the terminals B.sub.1 and B.sub.2 of each integrated capacity. These parasite capacities are shown with a broken line in FIG. 1.