High-speed radix-4 Add-Compare-Select unit for next generation communication systems

ACS (Add-Compare-Select) units are the most important block in FEC (Forward Error Correction) decoders such as Viterbi decoder and Turbo decoder. Due to the increase of performance requirement in next generation mobile communication systems such as LTE-Advanced, high speed operation of ACS units also becomes more important to achieve high throughput requirement. In this paper, we present three types of high-speed radix-4 ACS unit implementation for 12-bit operands and compare hardware complexities for various operating clock periods with 40% margin in 65nm CMOS process.