11.5 A 3.2×1.5×0.8mm3 240nA 1.25-to-5.5V 32kHz-DTCXO RTC module with an overall accuracy of µ1ppm and an all-digital 0.1ppm compensation-resolution scheme at 1Hz. - David Ruffieux; Franz-Xaver Pengg; Nicola Scolari; Frédéric Giroud; Daniel Séverac; Thanh Le; Silvio Dalla Piazza; Olivier Aubry (ISSCC, 2016)