Memory device tracking circuit
First Claim
Patent Images
1. A memory device tracking circuit comprising:
- a first comparator circuit having a first input and a second input, the first comparator circuit producing an output signal which indicates when a word line signal reaches a predetermined voltage;
a word line simulation circuit coupled to the first input; and
a bias circuit coupled to the second input for providing a bias voltage to the first comparator circuit which adjusts to changes in an external voltage supply.
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Abstract
Tracking circuitry is described for use in a memory device. The tracking circuitry be used to monitor word line voltages in a dynamic random access memory (DRAM) and includes a comparator circuit which compares a simulated word line signal to a digit line equilibrate bias voltage. The equilibrate bias voltage is generated using either memory column circuitry or a linear resistor voltage divider.
32 Citations
20 Claims
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1. A memory device tracking circuit comprising:
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a first comparator circuit having a first input and a second input, the first comparator circuit producing an output signal which indicates when a word line signal reaches a predetermined voltage; a word line simulation circuit coupled to the first input; and a bias circuit coupled to the second input for providing a bias voltage to the first comparator circuit which adjusts to changes in an external voltage supply. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A memory device comprising:
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voltage supply inputs for receiving an external voltage supply having an upper voltage level; a plurality of memory cells arranged in rows and columns; a plurality of access devices coupled between the plurality of memory cells and a digit line; a plurality of word lines coupled to the plurality of access devices, the plurality of word lines for communicating word line signals to selectively activate the plurality of access devices; and a tracking circuit for tracking the word line signals and producing an output which indicates when the word line signals reach a predetermined voltage level, the tracking circuit comprising a first comparator circuit having a first input and a second input, a word line simulation circuit coupled to the first input, and a bias circuit coupled to the second input for providing a bias voltage to the first comparator circuit. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of reading data from a memory device, the method comprising the steps of:
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producing a bias voltage using a bias circuit, the bias voltage approximating a digit line equilibrate voltage over temperature and voltage supply variations; comparing a word line signal to the bias voltage; and producing an output signal when the word line signal reaches a predetermined voltage differential above the bias voltage. - View Dependent Claims (17, 18, 19, 20)
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Specification