A low Vt CMOS implementation of an LPLV digital filter core for portable audio applications

A low power 32nd-order digital filter for portable audio applications has been designed and implemented in a single threshold 1-V 0.5-μm CMOS process. The design is full custom, using a combination of conventional CMOS and pass-transistor circuits, optimized for low energy consumption and small area. The filter features up to 16 biquad sections with programmable coefficients and performs fixed-point computations with 16-bit resolution. The measured average energy consumption of 330 pJ per biquad computation indicates that the implementation of complex digital signal processing in a single-threshold low-voltage process is a viable alternative to implementations in multiple threshold processes.