Electrical modeling for sub-millivolt noise in compact IoT system designs

All IoT systems require multiple sensors to collect environment information via analog to digital convertor (ADC). In several medical applications and industrial instrumentation, signals need to be captured with high resolution therefore the ADC requires an extremely quiet reference. This paper presents modeling and physical design considerations for a 12-bit ADC reference voltage supply to meet a 244 μV noise target. A fully differential approach is used in the electromagnetic and circuit modeling to capture noise on all parts of the passive network. Noise quantification accuracy is studied for different analyses that are part of the design flow: FEA, macro-modeling & SPICE simulation. Noise reduction in physical design through PVT invariant band gap and electromagnetic isolation through Faraday cage are investigated.