An integrated variable positive/negative temperature coefficient read reference generator for MLC PCM/NAND Hybrid 3D SSD

An integrated variable temperature coefficient (TC) reference generator for multi-level cell phase change memory (PCM)/NAND flash memory hybrid three dimensional solidstate drive is proposed and demonstrated by 0.18μm CMOS process. The proposed generator outputs both positive and negative TC reference current and voltage for PCM and NAND, respectively. TC is programmable and it can be widely changed down to -5.47mV/K and up to 5.74mV/K. Output level is also variable and it is independently controlled from the TC control. The flexible TC and output level control also enable a compensation of characteristics changes due to the program/erase cycling as wells as the process variations of the memory devices. The size of the reference generator is 0.195mm². The power consumption is 0.68mW at 120degC, 2.3V output.