An integrated Shunt-LDO regulator for serial powered systems

In this paper, a new type of regulator is proposed for integration in ASICs used in serially powered systems. In the serial powering scheme, modules are placed in series and fed by a constant current source to reduce the IR drop on the cables which increases powering efficiency. At the module level the needed supply voltages are generated redundantly out of the current supply by several parallel operating ASICs with integrated regulation circuitry. A Shunt-LDO regulator has been developed to allow robust and redundant regulator operation and the generation of different supply voltages by parallel placed devices. The Shunt-LDO regulator scheme combines the capability of Low Drop-Out regulators to generate a constant supply voltage with the feature of shunt regulators to assure a constant current flow through the device. The Shunt-LDO regulator has been developed for application in the framework of next generation hybrid pixel detectors used in high energy physics experiments. This circuit has been prototyped in a 130 nm CMOS technology, capable of generating voltages in a range of 1.2-1.5 V with a minimum drop out voltage of 200 mV. The maximum shunt current is 500 mA with a load regulation factor corresponding to an output impedance of 30 mOmega.