A fully isolated delta-sigma ADC for shunt based current sensing

This paper presents the world's first chip-level 5kV isolated delta-sigma ADC architecture which realizes the isolation in both the power and signal domains. The IC package contains an integrated isolated power converter (including an on-chip transformer, oscillator and rectifier), three analog to digital converters, a voltage reference, a temperature transducer, on-chip data transformers, and a controller/communication chip. This solution displaces the need for isolation using opto-couplers or costly, bulky and frequency dependent current transformers, and enables lower cost shunt-based current sensing for domestic and industrial energy metering applications. It also enables new portable industrial current sensing applications where voltage isolation is necessary. The whole system-in-a-package draws 12.5mA from a 3.3V supply and achieves 74.4dBFS SNDR and 80.8dBFS SFDR in a bandwidth of 3.3 kHz. It also achieves an insulation voltage rating of 5000Vrms over a 1 minute duration.