A 19 nW analogue CMOS log-domain 6th-order Bessel filter without E-minus cells

This paper contributes to the field of low-power high-order CMOS log-domain filters by: (a) suggesting a log-domain synthesis path which bypasses the need for E-minus cells and (b) by assessing the practicality of the proposed synthesis path by means of a 6th-order CMOS log-domain Bessel filter fabricated in the commercially available AMS 0.35@mm process. Measured results from the 19nW, 8-200Hz, 940@mm^2 Bessel filter chip confirm the validity of the proposed approach. The filter reported here is particularly useful for biomedical instruments such as portable ECG devices and Pulse-oximeters.

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