Two-quadrant fully integrable rms-to-dc converter for handling low-frequency signals

A novel current-mode rms-to-dc converter architecture is introduced in this paper. It is constructed from a current squaring stage and a lowpass filter with low cutoff frequency realized using the concept of Log-Domain filtering. Due to the employment of the current-splitter, two-quadrant operation capability is achieved by the converter. The Log-Domain technique offers the benefits of large-signal operation and realization of the required time-constant using a capacitor of an integrable value. Another attractive feature of the proposed scheme is its low-power operation capability originated from the employment of MOS transistors operated in the subthreshold region and its simple circuitry.