Apparatus and method for regenerating charge
AssigneeBell Telephone Laboratories, Incorporated
InventorJames Albert Cooper, Jr.
Life of this patent
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Abstract
An apparatus and a method for regenerating charge packets representing logical information in a charge transfer device uses a pattern of field plate electrodes and impurity zones to perform arithmetic operations. To regenerate a charge packet it is first multiplied by a factor dependent upon transfer imperfections. Then an amount of charge representing a logical 0 is substracted from the charge packet. Finally, the magnitude of the charge packet is limited to the amount of charge representing a logical 1.
Claims25
A semiconductor apparatus including first and second charge transfer device sections of the type adapted for the storage and serial transfer of charge carriers localized in induced potential wells along a surface portion of a body by sequentially applying a plurality of differing potentials to successive portions of the surface and further adapted for logical bit regeneration, said apparatus comprising:
- means for detecting a charge packet output of the first charge transfer device section and for multiplying said charge packet by a multiplication factor so that after multiplication the difference in the amount of charge in a charge packet representing a logical 1 and in a charge packet representing a logical 0 is at least as great as the maximum charge storage capacity of a potential well of the second charge transfer device section, said means for multiplying including a semiconductor charge storage region controlled by an overlying electrode of such geometry as to produce a sufficient storage capacitance that the region in response to said output stores a charge packet which is amplified compared with the storage packet output;
- means for subtracting a fixed quantity of charge from the multiplied charge packet, sufficient to remove the charge of a charge packet representing a logical zero, said means for subtracting including a second semiconductor charge storage region controlled by an overlying electrode;
- and
- means including a localized impurity zone charge sink for limiting the amount of charge in the charge packet to a maximum value equal to the minimum charge storage capacity of a potential well of the second charge transfer device section.
A semiconductor apparatus of the type adapted for the storage and serial transfer of charge carriers localized in induced potential wells along a surface portion of a body of a first type semiconductivity by sequentially applying a plurality of differing potentials to successive portions of the surface through field plate electrodes and further adapted for logical bit regeneration, said apparatus comprising:
- a first zone of a second type semiconductivity disposed within the body and adjacent one of the field plate electrodes for sensing the number of charge carriers existing under said one field plate electrode,
- a second zone of the second type semiconductivity disposed within the body,
- a source electrode contacting the second zone for supplying charge carriers,
- an output electrode for accumulating charge carriers and creating an output potential well, and
- a control field plate electrode in contact with the first zone, disposed over and insulated from the body, and between the source electrode and the output electrode for creating in the body beneath the control field plate electrode a control potential barrier,
- the apparatus further including:
- an amplifying field plate electrode disposed over and insulated from the body and between the control field plate electrode and the output electrode, for creating in the body beneath the amplifying field plate electrode an amplifying potential well with a charge storage capacity greater than the charge storage capacity of the first zone,
- a third zone of the second type semiconductivity disposed within the body,
- a first sink field plate electrode contacting the third zone for accumulating charge carriers,
- a transfer field plate electrode disposed over and insulated from the body, and between the amplifying field plate electrode and the output electrode and between the amplifying field plate electrode and the first sink field plate electrode, for creating in the body beneath the transfer field plate electrode a transfer potential well with a charge storage capacity at least as great as the charge storage capacity of the amplifying potential well,
- a subtraction field plate electrode disposed over and insulated from the body, and between the transfer field plate electrode and the first sink field plate electrode, for creating in the body beneath the subtraction field plate electrode a subtraction potential well with a charge storage capacity less than the charge storage capacity of the amplifying potential well,
- a fourth zone of the second type semiconductivity disposed within the body,
- a second sink field plate electrode contacting the fourth zone for accumulating charge carriers, and
- a limiting field plate electrode disposed over and insulated from the body and between the transfer field plate electrode and the output electrode and between the transfer field plate electrode and the second sink field plate electrode, for creating in the body beneath the limiting field plate electrode a limiting potential well with a charge storage capacity not greater than the charge storage capacity of the output potential well.
A method for use with a charge transfer device for regenerating charge packets emanating from a first transfer device section for injection into a second transfer device section, said packets representing logical 1's and 0's comprising the steps of:
- multipying a charge packet emanating from the first transfer device section by a multiplication factor so that after multiplication the difference in the amount of charge in a charge packet representing a logical 1 and in a charge packet representing a logical 0 is at least as great as the maximum charge storage capacity of a potential well of the second transfer section,
- subtracting by shifting a fixed quantity of charge from the multiplied charge packet, sufficient to remove the charge of a charge packet representing a logical 0 and
- limiting the amount of charge in the charge packet to a maximum value equal to the minimum charge storage capacity of a potential well of the second transfer device section by shifting of excess charge into a localized impurity zone charge sink.
Dependencies are inferred from the claim text.