Semiconductor filtering apparatus
AssigneeReticon Corporation
InventorGene P. Weckler
Life of this patent
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Abstract
A semiconductor filtering apparatus substantially fabricated as a metal-oxide-semiconductor (MOS) integrated circuit that permits discrete time correlation or convolution of an analog input signal with a binary or analog correlating signal. The apparatus may also be employed as a recursive filter. A plurality of novel bucket-brigade charge transfer means are employed to shift the input analog signal past non-destructive read-out taps. Electrically programmable floating gate devices are used to store either a binary or analog correlating signal. The sum or difference signal associated with each of the plurality of charge transfer means is weighted to produce the final filter output in one embodiment.
Claims13
In a semiconductor filter which includes a charge transfer means for transferring an input signal, said transfer means including a plurality of nodes for sensing charge in said transfer means, an improvement for selectively coupling said nodes comprising:
- a plurality of electrically programmable MOS devices each of which includes a pair of spaced apart regions disposed in a substrate and a floating gate insulation from, and disposed above, said substrate, each of said floating gates being completely surrounded by oxide, each of said devices being coupled to one of said nodes;
- whereby a connection, or open connection, may be made to nodes in said transfer means by selectively injecting charge onto said floating gates thereby permitting programming of said filter.
In a semiconductor filter employing at least one bucket-brigade transfer means, said transfer means having a plurality of taps, an improvement for non-destructively, and selectively, sensing signals at said taps comprising:
- a plurality of readout field-effect transistors, each including a gate coupled to a different one of said taps;
- a first readout line;
- and
- a plurality of electrically programmable MOS floating gate devices coupling each of said readout transistors to said first readout line, each of said floating gate devices including a floating gate completely surrounded by oxide;
- whereby said MOS floating gate devices may be selectively programmed thereby coupling predetermined taps to said first readout line.
A semiconductor filter comprising:
- a plurality of bucket-brigade transfer means disposed on a silicon substrate;
- a plurality of field-effect transistors disposed on said substrate and coupled to said transfer means for sensing charge in said transfer means;
- a plurality of readout lines, disposed on said substrate;
- and,
- a plurality of electrically programmable floating gate devices, each of said devices coupling one of said transistors to one of said readout lines, said devices being disposed on said substrate and each of said devices including a floating gate completely surrounded by oxide;
- whereby said floating gate devices may be electrically programmed with a predetermined function and the filtered signal sensed on said readout lines.
A semiconductor filter comprising:
- an MOS bucket-brigade charge transfer means, for receiving an input signal and for transferring charge representative of said input signal, said transfer means including a plurality of tap means for sensing charge in said transfer means,
- at least one line;
- and
- a plurality of MOS electrically programmable floating devices each device including a pair of spaced-apart regions and a floating gate completely surrounded by oxide, for storing charge, each of said devices being coupled between one of said tap means and said line;
- whereby said floating gate devices may be selectively programmed permitting predetermined coupling between said tap means and said line, thereby permitting filtering of said input signal.
Dependencies are inferred from the claim text.