Sensors for built-in alternate RF test

Abstract

The paper discusses a variety of sensors to enable a built-in test in RF devices. The list of sensors includes dummy circuits, process control monitors, DC probes, an envelope detector, and a current sensor. Dummy circuits and process control monitors are simple circuits that do not tap into the signal path of the RF device. Instead, they monitor the device by virtue of being subject to the same process variations. Their outputs form an alternative measurement pattern which can be mapped to the performances of the device using a typical alternate test flow. The rest of the sensors are physically connected to the RF device, thus they can detect random catastrophic defects within it and, as an auxiliary benefit, they can improve the accuracy in predicting its performances. The degradation that these sensors incur is carefully assessed and the RF device is co-designed with them to correct for the losses. The operation and test efficiency of the sensors is demonstrated for the case of an RF LNA using post-layout simulations.