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High Speed Read Circuit for Embedded Arrays

IP.com Disclosure Number: IPCOM000062439D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Carter, EL: AUTHOR

Abstract

An embedded array features a common base input-type read circuit that reduces voltage swing on the read bit lines, making address access time less dependent on the word size of the array. This is done by preceding the read circuit pull-up resistors with common base input stages. This buffers the pull-up resistors from the capacitive loading on the array cell outputs, and it yields a very low read circuit input impedance. Also, since the common base stage has a constant DC current bias, the read circuit inputs maintain a relatively constant voltage while the array cell current outputs are being sensed. Therefore, there is very little delay due to capacitive dV/dT effects. The read circuit is shown in Fig. 1. To accommodate the common base read input stages, the array cell must contain a diode shift, as shown in Fig. 2.

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High Speed Read Circuit for Embedded Arrays

An embedded array features a common base input-type read circuit that reduces voltage swing on the read bit lines, making address access time less dependent on the word size of the array. This is done by preceding the read circuit pull-up resistors with common base input stages. This buffers the pull-up resistors from the capacitive loading on the array cell outputs, and it yields a very low read circuit input impedance. Also, since the common base stage has a constant DC current bias, the read circuit inputs maintain a relatively constant voltage while the array cell current outputs are being sensed. Therefore, there is very little delay due to capacitive dV/dT effects. The read circuit is shown in Fig.
1. To accommodate the common base read input stages, the array cell must contain a diode shift, as shown in Fig. 2. The read and write decode circuits must be similarly diode shifted.

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