An Offset-Tolerant Fast-Random-Read Current-Sampling-Based Sense Ampli fier for Small-Cell-Current Nonvolatile Memory Meng-Fan Chang, Shin-Jang Shen, Chia-Chi Liu, Che-Wei Wu, Y u-Fan Lin, Y a-Chin King, Chorng-Jung Lin, Hung-Jen Liao, Y u-Der Chih, and

Abstract

Decreasing read cell current has become a major trend in nonvolatile memory (NVM ). However, a reduced leaves the operation of the sense ampli fier (SAs) vulnerable to bitline (BL) level offset and SA input offset. Thus, small- NVMs suffer from slow read speed or lo w read yield. In this study, we propose a new current-sampling-based SA (CSB-SA) to suppress the offset due to device mismatch, while maintaining tolerance for insuf ficient precha rge time. These features enable CSB-SA to achieve a read speed 6.3 -8.1 faster than previous SAs, for sensing 100 nA on a 2 K-cell bitline. We fabricated a CMOS-logic-compatible, 9 0 nm, 512 Kb OTP macro, using the CSB-SA. This OTP macro achieves a random access time of 26 ns for reading sub-200 nA .M e a s u r e m e n t sc o nfirm that this 90 nm CSB-SA is also capabl e of sub-100 nA sensing.