Circuit characterization of low frequency noise in 45nm technology bandgap

Abstract

Circuit characterization for low frequency noise of a bandgap reference circuit in a 45nm CMOS process is performed here. It is determined that the noise at lower frequencies follow 1/fγ spectra where 1<γ<2. This flattens off as thermal noise for frequencies greater than 1 KHz. Substantial variation in bandgap noise is observed which is demonstrated to be largely uncorrelated to bandgap trim voltage. Possible noise generating components within the bandgap circuit are identified. The dominant contributor for the observed 1/fγ nature of the bandgap noise is identified as the noise generated within the operational amplifier circuit block.