A four-bit full adder implemented on fast SiGe FPGAs with novel power control scheme

The low operating speed of current CMOS Field Programmable Gate Arrays (FPGAs), i.e., 10-220 MHz, has prevented their use in high-speed digital applications. With the advent of IBM Silicon Germanium (SiGe) 7HP technology, designers have been able to design FPGAs operating in the gigahertz range. This paper is going to elaborate on the implementation of a 4-bit ripple-carry full adder (FA) on the new SiGe FPGA with new architectures and a novel power management strategy. The 1-bit FA can be realized in three Configurable Logic Blocks (CLBs). Apart from these, the FA can operate in multiple modes: FAST, NON-CRITICAL, SLOW and OFF. The propagation delays of the 1-bit FA and 4-bit ripple-carry FA are 240 ps and 675 ps respectively in the FAST mode. All the simulation and layouts were done using Cadence 4.4.6 and IBM SiGe 7HP design kit version 1.1.1.0.