Erasable programmable read-only memory
First Claim
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1. A read-only memory deployed on a doped silicon substrate comprising:
- a first region on said substrate having a higher dopant level than said substrate;
a plurality of memory cells disposed in said first region, each of said cells including a floating gate for storing charge;
a plurality of buffers disposed on said substrate, spaced apart from said first region, for communicating signals to said memory cells, each of said buffers including a plurality of field-effect transistors having channels with a first level of dopant and at least one field-effect transistor having a channel with a second level of dopant wherein said saecond level of dopant is higher than said first level of dopant;
whereby said buffers act as level shifters to permit signals to be readily transmitted to said memory cells.
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Abstract
A TTL compatible erasable programmable read-only memory (PROM) which uses a single n-channel device having a floating gate for each memory cell. The entire memory including the periphery circuits, are disposed on a silicon substrate. Only a single externally generated high voltage input or "pin" is required for programming.
31 Citations
19 Claims
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1. A read-only memory deployed on a doped silicon substrate comprising:
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a first region on said substrate having a higher dopant level than said substrate; a plurality of memory cells disposed in said first region, each of said cells including a floating gate for storing charge; a plurality of buffers disposed on said substrate, spaced apart from said first region, for communicating signals to said memory cells, each of said buffers including a plurality of field-effect transistors having channels with a first level of dopant and at least one field-effect transistor having a channel with a second level of dopant wherein said saecond level of dopant is higher than said first level of dopant; whereby said buffers act as level shifters to permit signals to be readily transmitted to said memory cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In a semiconductor memory disposed on a single silicon substrate and which includes a plurality of storage memory cells each of which has a floating gate for storing charge, a sense amplifier coupled to said cells comprising:
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a first branch which includes a first load means and a first transistor, said first transistor being coupled to said storage memory cells; a second branch coupled in parallel with said first branch, said second branch including a second load means and a second transistor; a memory cell for establishing a reference potential, said memory cell including a floating gate, said memory cell being coupled to said second transistor; whereby the reference potential provided by said memory cell establishes a level for said sense amplifier. - View Dependent Claims (15, 16, 17)
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18. A memory circuit having a plurality of floating gate MOS memory cells fabricated on a single silicon substrate comprising:
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means for establishing a predetermined substrate voltage, said substrate voltage being coupled to each of said cells; means for establishing an external reference voltage difference from said substrate voltage; a a first buffer circuit including a first FET having a channel having a first predetermined dopant level, said first FET being biased with respect to said external reference voltage; a level shifter having its input coupled to said first buffer circuit, said level shifter including a second FET having a channel having a second predetermined dopant level higher than said first predetermined dopant level, and a third FET, series-coupled to said second FET, having a channel having said first predetermined dopant level, said level shifter providing its output from said third FET; a second buffer circuit coupled to the output of said level shifter, including a fourth FET having a channel having said first predetermined dopant level series-coupled to a fifth FET having a channel having said second predetermined dopant level, said second buffer circuit providing its output from said fifth FET said fifth FET being biased with respect to said substrate voltage. - View Dependent Claims (19)
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Specification