Design of 32 kbit one-time programmable memory for microcontroller units

Abstract

A 32 kbit OTP (one-time programmable) memory for MCUs (micro-controller units) used in remote controllers was designed. This OTP memory is used for program and data storage. It is required to apply 5.5 V to BL (bit-line) and 11 V to WL (word-line) for a OTP cell of 0.35 μm ETOX (EEPROM tunnel oxide) type by MagnaChip. We use 5 V transistors on column data paths to reduce the area of column data paths since they require small areas. In addition, we secure device reliability by using HV (high-voltage) transistors in the WL driver. Furthermore, we change from a static logic to a dynamic logic used for the WL driver in the core circuit. Also, we optimize the WD (write data) switch circuit. Thus, we can implement them with a small-area design. In addition, we implement the address predecoder with a small-area logic circuit. The area of the designed 32 kbit OTP with 5 V and HV devices is 674.725 μm×258.75 μm (=0.1745 mm2) and is 56.3% smaller than that using 3.3 V devices.