A 1.2-V 90-MHz Bitmap Index Creation Accelerator with 0.27-nW Standby Power on 65-nm Silicon-On-Thin-Box (SOTB) CMOS

Although bitmap index (BI) can surmount complex and multi-dimensional queries, the creation of BI itself is a time-consuming task. Many studies exploit the highly parallel processing capabilities of multi-core CPUs, graphics processing units (GPUs), or field-programmable gate arrays (FPGAs) to overcome this obstacle. This study, on the other hand, proposes a 65-nm silicon-on-thin-buried-oxide (SOTB) hardware accelerator dedicated to BI creation. The fabricated chip could operate at different supply voltages, from 0.45-V to 1.2-V. Concretely, in the active mode with the supply voltage of 1.2-V, this chip was fully operational at 90-MHz and consumed approximately 88.1pJ/cycle. In the standby mode with the supply voltage of 0.45V and clock gated, the power consumption was only 476.1-nW. Moreover, when the reverse back-gate bias voltage of -2.5-V is supplied, the standby power sharply dropped to 0.27-nW or approximately 1,763 times. This achievement is vitally essential for the energy-efficient applications, where the performance should be maximized during peak workload hours and the power should be minimized during off-peak time.