High-speed wireless sensor networks are currently being considered for a variety of communication applications such as environmental, medical, industrial or security scenarios. For increased transmission rates given the limited embedded battery lifetime, ultra-low-power circuitry is needed in the sensors and processors. Much research is being undertaken in these different areas at the device, circuit, system and network levels. Although using error control coding (ECC) potentially reduces the required transmit power for reliable communication, higher decoder complexity increases the required processing energy. The above tradeoff is explored in this paper to find when use of ECC results in more power-efficient systems. Several recently implemented decoders are analyzed, comparing both analog and digital implementations. The four most energy-efficient decoders are analog decoders. The best analog decoder becomes energy-efficient at about 1/4 the distance of the best digital implementation.