Low Frequency CMOS Two-Integrator Oscillator for IoT Applications

E. Mendes, J.P. Oliveira, L. Oliveira (Univ. Nova de Lisboa, Portugal)

In this work a quasi-linear quadrature two‑integrator RC oscillator is used for impedance meter. This topology has the advantage of having low distortion at low frequencies and it allows to tune the frequency of oscillation in a wide range of frequencies, while providing two differential quadrature outputs. In order to have the smallest possible area the capacitors are implemented with two parallel MOS transistors. It is intended that the transistors have low transconductance, thus, low current, and consequently the circuit will have the lowest possible power consumption, which is required for IoT (Internet of Things) applications. A circuit design is done in a 130 nm standard CMOS technology. The circuit power consumption is 3.18 mW, and a THD of -49 dB is obtained for a frequency of 20 kHz.