US 4,305,139 A · State detection for storage cells

Abstract

For signal storage systems that interrogate a storage cell with a concomitant precharging of the cell signal line, non-linear capacitors are employed to provide automatic selective coupling of the respective signal line to a detector for determination of the cell state. By connecting a plurality of signal lines to a detector through respective non-linear capacitors that assume a significantly enlarged capacitance when the precharge voltage level is asserted, enhanced coupling of the signal line may be achieved and by selectively precharging the signal line to be interrogated, no triggering of enlarged capacitance at other signal lines occurs to load the detection system. In a preferred symmetrical configuration for use with a reference comparison type of detection, shifts in the discharge characteristics for the two comparison inputs to the cell state detector resulting from manufacturing variations tend to cancel, thus permitting more sensitive detection to be employed. To complement the preferred configuration, a special reference circuit using a pair of joined signal lines provides a ramp signal having intermediate voltage values relative to the state-indicative signals produced by interrogated cells for the two respective cell states. By using a reference circuit that is located with and uses the same devices as the storage circuitry, any shifts in characteristics as a result of manufacturing variations have a greater tendency to cancel in the signal comparison.

Claims11

Dependent claims

A binary signal storage device responsive to a cell identifier signal, said device comprising:

a first and a second bank of individual storage signal lines which exhibit an effective capacitance and have storage cells connected thereto that are individually selectable to control the conducting state of a discharge path for a respective signal line in accordance with a preconditioning of said cells,
a comparison-type detector having first and second terminals for receiving inputs,
multiplexer means responsive to said identifier signal for selectively coupling the signal line corresponding to an identified cell to an input terminal of said detector, which multiplexer means couples signal lines from said first bank to said first detector terminal and signals from said second bank to said second detector terminal,
a first reference waveform circuit associated with said first bank and consisting of a pair of signal lines that are connected through a conducting link to exhibit paralleled capacitance and are connected to discharge through a network of preconditioned storage cells,
a second reference waveform circuit associated with said second bank and consisting of a pair of signal lines that are connected through a conducting link to exhibit a paralleled capacitance and are connected to a discharge network of preconditioned storage cells,
said multiplexer means further including means for identifying the reference circuit associated with the bank that does not include the identified cell and means for coupling the identified reference circuit to the corresponding detector input terminal, whereby a comparison of waveforms for the signal line of the identified cell and for a reference circuit may be effected.

3 more elements

A reference waveform circuit for a storage unit of the type that has plural signal lines which exhibit an effective capacitance and are connected to storage cells that are conditioned to either of two states and are selectable to control a discharge path for the signal line associated therewith to be either conducting or non-conducting, which storage unit includes a detector that compares discharge waveforms applied at respective of two input terminals during cell interrogation operations, said reference waveform circuit comprising:

a pair of signal lines;
means for charging said pair of signal lines to a predetermined voltage level as an incident to cell interrogation operation, a connecting path that electrically connects said pair of signal lines to permit electrical charge transfers therebetween;
means for coupling said pair of signal lines to one of said input terminals of said detector at least during a part of a cell interrogation operation, and having a network of storage cells connected thereto that are connected to define at least one discharge path for said signal line pair;
means, cooperating with said network of cells, for enabling one and only one of said discharge path(s) for said signal line pair to conduct during a cell interrogation, whereby a discharge waveform exhibiting a relatively long time constant is produced.

1 more element

Dependencies are inferred from the claim text.

State detection for storage cells

Life of this patent

State detection for storage cells

Life of this patent

Abstract

Claims11