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Method for a single-ended sensing scheme for SRAM

IP.com Disclosure Number: IPCOM000010170D
Publication Date: 2002-Oct-30
Document File: 3 page(s) / 91K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a single-ended sensing scheme for SRAM. Benefits include improved performance and improved functionality.

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Method for a single-ended sensing scheme for SRAM

Disclosed is a method for a single-ended sensing scheme for SRAM. Benefits include improved performance and improved functionality.

Background

              Single-ended sensing is widely used in register files and SRAMs with a short bit-line height.  Standard domino circuits are typically used in single-ended sensing schemes. A standard single-ended sensing circuit typically uses a PMOS transistor for each bit-line as first-level multiplexing to select a column as, for example, in 4-to-1 multiplexing (see Figure1). The first stage domino sensing circuit is comprised of a precharge (P01), a keeper (P02, I1), and a highly skewed inverter (P1 and N1, where P1>>N1). Second stage sensing is comprised of a keeper (N10, I2), a predischarge device (N11), and a pull-down NMOS N2. The pull-down (N1) in the first stage may not be required if the keeper (P02) is sufficiently large. In a read operation, one of the bit lines is accessed (bit 0). The BLX is pulled down by the bit-line if a “0” is being read out. The bit-line and BLX should stay high when a “1” is being read out. Due to increasingly significant leakage current with technology scaling, the bit-line is pulled-down by leakage current between the bit-line and memory cells. A keeper device (P02) is required to fight the leakage and ensures correct logic operation. P02 slows down the sensing speed when a “0” is being read out because its presence reduces the effective current (for pulling down the node BLX) from Iread to Iread – I02. The N1 impacts negatively on the sensing speed because the trip point of the inverter (P1 and N1) is lower than VCC-VT.

Description

              The disclosed method is a single-ended sensing scheme...