Low-power implementation of the Bluetooth subband audio codec

This paper describes a low-power implementation of the Bluetooth subband codec (SBC) for high-fidelity wireless audio. The design uses a configurable weighted overlap-add (WOLA) filterbank coprocessor to implement the analysis and synthesis filterbanks. A new method to convert the two-times over-sampled, complex WOLA subband signals to equivalent critically sampled, real-valued SBC subband signals is presented. The WOLA coprocessor allows for an efficient parallel implementation of the filterbank and quantization portions of the SBC algorithm. Details of the overall system design are also presented, including measurements of power consumption and resource requirements. The final real-time, fixed-point implementation is compared to an off-line floating-point reference and found to produce no audible difference in decoded signal quality.