Programmable log-domain low pass filter

This paper presents a programmable low-pass filter implemented with log-domain building blocks; the blocks have Externally Linear Internally Nonlinear (ELIN) structures derived using LIN-ELIN transformations. The order of the proposed filter transfer function can be set to 3^rd, 4^th or 5^th by a digital control word; the main filter parameters can be tuned/adjusted by using the bias currents of the building blocks.