180-mV Subthreshold Operation of Crystalline Oxide Semiconductor FPGA Realized by Overdriving Programmable Power Switch and Programmable Routing Switch<br />

Abstract

A crystalline oxide semiconductor (OS) FPGA capable of subthreshold operation is developed.To achieve subthreshold operation, the OS FPGA employs overdriving of a programmable routing switch and a programmable power switch for power gating by using OS FFT as an ideal floating gate with excellent charge retention. In a prototype chip fabricated with a 0.8-m OS/0.18-m CMOS hybrid process, while maintaining features realizing low power consumption proposed in our previous studies [1, 2], the following are shown: a configured combinational circuit operates at a minimum operating voltage (V min ) of 180 mV, a configured sequential circuit operates at V min of 190 mV with 12.5 kHz, and the minimum power-delay product scores 3.40 pJ/operation at 330 mV.

Subthreshold Operation of CAAC-IGZO FPGA by Overdriving of Programmable Routing Switch and Programmable Power Switch

“…A CAAC-IGZO FPGA prototype chip was fabricated using a 0.8-μm CAAC-IGZO/0.18-μm CMOS hybrid process as well as a PLE test element group (TEG) composed of one PLE [38]. The withstand voltage exceeding write voltages is not required because the voltage of N cfg or N ctx increases along with the increase in the S/D voltage.…”

16‐1: Low‐Power Oxide‐Semiconductor Display System

“…In our system, a host device (application processor, AP) is an N-off device using OS LSI. For example, any of the N-off processors [9][10][11], any of the NOSRAM [17,18] and the DOSRAM [19], and any of the OS FPGAs [12][13][14][15][16] are applicable to a host processor, a storage device (a main storage device or working memory), and a controller or a programmable device, respectively.…”

“…An image data stream from a host PC is converted into the desired data format by the display controller, which comprises a printed circuit board (PCB) incorporating OS LSI, and is then transmitted to the OS display. Note that the OS display system is constructed using any of the hybrid displays [5][6][7] as the OS display and any of the OS FPGAs [12][13][14][15][16] as the OS LSI.…”

“…OS-FETs have been applied to LSI as well as displays [8]. Examples of OS LSI in which nonvolatile memory elements are built with OS-FETs exhibiting ultralow off-state current include normally-off (N-off) processors [9][10][11], nonvolatile FPGAs (OS FPGA) [12][13][14][15][16], nonvolatile oxide semiconductor random access memory (NOSRAM) [17,18], dynamic oxide semiconductor random access memory (DOSRAM) [19], a global-shutter image sensor [20], and a vision sensor [21]. The possibility of device scaling has been verified [22], and prototyping of OS LSI using a foundry's 65-nm Si process has been reported previously [23,24].…”