A Low Noise Relaxation Oscillator with Second Order Temperature Compensation Technique

Abstract

This paper presents a relaxation Oscillator (RxO) with a low noise and temperature insensitivity operation through a second order compensation technique in swing-boosted structure. The proposed RxO overcomes the limitation of swing-boosted RxO’s temperature characteristic by tracking the initial voltage level of the charging and the discharging phase during the oscillation and adjusting the voltage level from two series connected 1st temperature compensated resistors. Simulation results show that this RxO has a 2MHz frequency and temperature Characteristic (TC) is 13.1~47.8ppm/℃ at three corners, and the FoMTC = 174, which is large. In addition, the power consumption is 36uW as averaging at the nominal corner, the phase noise at 100KHz offset frequency is -115dBc/Hz, and the FoMjitter is -156dBc/Hz. The total area is 242.8 x 211um2 and was designed in the TSMC 55nm process.