A 7.92 Gb/s 437.2 mW Stochastic LDPC Decoder Chip for IEEE 802.15.3c Applications

Abstract

This paper presents the first silicon-proven stochastic LDPC decoder to support multiple code rates for IEEE 802.15.3c applications. The critical path is improved by a reconfigurable stochastic check node unit (CNU) and variable node unit (VNU); therefore, a high throughput scheme can be realized with 768 MHz clock frequency. To achieve higher hardware and energy efficiency, the reduced complexity architecture of tracking forecast memory is experimentally investigated to implement the variable node units for IEEE 802.15.3c applications. Based on the properties of parity check matrices and stochastic arithmetic, the optimized routing networks with re-permutation techniques are adopted to enhance chip utilization. Considering the measurement uncertainties, a delay-lock loop with isolated power domain and a test environment consisting of an encoder, an AWGN generator and bypass circuits are also designed for inner clock and information generation. With these features, our proposed fully parallel LDPC decoder chip fabricated in 90-nm CMOS process with 760.3 K gate count can achieve 7.92 Gb/s data rate and power consumption of 437.2 mW under 1.2 V supply voltage. Compared to the state-of-the-art IEEE 802.15.3c LDPC decoder chips, our proposed chip achieves over 90% reduction of routing wires, 73.8% and 11.5% enhancement of hardware and energy efficiency, respectively.