Advanced network-on-chip (NOC) designs using nano-scale technologies face a number of challenges, especially for great amount of energy consumption in switch fabrics and link wires. In this paper, some energy-efficient techniques are presented for circuit design in network-on-chip platforms, including low-power and variation-tolerant link wires, adaptive congestion-aware routing and asynchronous two-level FIFO buffers. Energy-efficient and reliable link wires are provided by a novel self-calibrated low-power coding and voltage scaling interconnection architecture. This approach makes the NoC applications tolerant of transient malfunctions and realizes energy efficiency. Additionally, an adaptive congestion-aware routing is proposed to reduce the average latencies by avoiding the congestion conditions and distributed hotspots. Moreover, an asynchronous two-level FIFO buffer can reduce energy consumption compared with that of synchronous two-level FIFO buffers and conventional asynchronous output buffers.