29% Power Saving through Semi-Custom Standard Cell Re-Design in a Front-End for Hearing Aids

Two versions of a front-end circuit for hearing aids have been placed on the same die fabricated in 0.18μm CMOS technology. The VHDL source code has been the same in either case. The difference has been in the set of standard cells made available to the synthesis tool. In the reference design, this has been a regular industrial cell library, while a few hand-crafted cells featuring transistors of minimum size have been added for the second design. Measurements on real silicon show that the second version saves about 30% of energy compared to the reference with about one quarter of all cells replaced by minimum drive versions.