Built-In-Test of Analog and RF Circuits using Embedded Sensors

Testing of on-chip RF and microwave circuits has always been a challenge to the test engineers. Since the emergence of System-on-a-Chip (SoC), characterization and test development is time-consuming and they contribute to a significant part of the manufacturing cost. Moreover, test development of RF and microwave circuits requires years of experience and expertise. In this paper, we propose to use built-in-test in the form of specific sensors. Instead of testing the devices specifically for certain performance metrics, the output values of the sensors, which are usually DC or a very low frequency signal, can be used to get a quick and accurate estimate of the behavior of the device under test (DUT). For a relatively low-yielding process, which is usually the case for RF and microwave circuits, significant number of faulty devices can be identified without even performing the standard manufacturing test on the devices. Moreover, these sensors can also be used for on-line test. In this paper, we also propose an algorithm to optimally place the sensors at the outputs for a system-under-test and use the sensor outputs to get an estimate of the specifications of the system-under-test. Using this method, specifications can be estimated within an accuracy of ±3% of its actual value.