An advantage of an RLD (reconfigurable logic device) such as an FPGA (field programmable gate array) is that it can be customized after being manufactured. Due to the aggressive technology scaling, device density is increasing, and it has become a serious problem in power consumption accordingly. In SoC of embedded systems, power gating is one of the major power reduction techniques. However, it is difficult to adopt SRAM-based RLDs because of the high overhead and SRAM being volatile. In this paper, we describe a TEG (test element group) chip of a reconfigurable logic based FeRAM (ferroelectric random access memory) technology. FeRAM brings reconfigurable logic devices the advantage of being a genuine power gater. The chip employs island-style routing architecture and uses a variable grain logic cell as a logic block. A NV-FF (non-volatile flip-flop), which contains FeRAM, a FF, and power-gating control circuits, is used as both configuration memories and FFs in a logic block. The NV-FF can transmit data between FeRAM and FF automatically when a power source is turned off/on. Thus chip-level power gating is possible. The hibernate/restore time is less than 1 ms. The chip has 1818 logic blocks and an area of 54.76 mm2.

Generally, a programmable LSI such as an FPGA is difficult to test compared to an ASIC. There are two major reasons for this. The first is that an automatic test pattern generator (ATPG) cannot be used because of the programmability of the FPGA. The other reason is that the FPGA architecture is very complex. In this paper, we propose a new FPGA architecture that will simplify the testing of the device. The base of our architecture is general island-style FPGA architecture, but it consists of a few types of circuit blocks and orderly wire connections. This paper also presents efficient test configurations for our proposed architecture. We evaluated our architecture and test configurations using a prototype chip. As a result, the chip was fully tested using our configurations in a short test time. Moreover, our architecture can provide comparable performance to a conventional FPGA architecture.