Abstract: A method and apparatus for testing analogue or RF circuitry, wherein the power supply VDD is ramped up (step 100) and quiescent current measurements are taken at selected values of VDD (step 102) to generate a current signature (step 104). When the power supply is ramped up, all transistors in the circuit pass through several regions of operation, e.g. subthreshold (region A), linear (region B), and saturation (region C). The advantage of transition from region to region is that defects can be detected with distinct accuracy in each of the operating regions. Once the current signature has been generated it can be compared with the current signature of a fault-free device (step 106), to determine (step 108) if the device is operating correctly, and if not, it is discarded.

Abstract: According to an example embodiment, there is a testing device for testing a phase locked loop having a power supply input. The testing device comprises a power supply unit for providing a power supply signal VDD having a variation profile to the power supply input of the phase locked loop, wherein a width and height of said variation profile are formed in such a way, that the voltage controlled oscillator is prevented from outputting an oscillating output signal. There is a means for disabling a feedback signal to a phase comparator of the phase locked loop such that said phase locked loop is operated in an open loop mode, and a meter for measuring a measurement signal of the phase locked loop, while said power supply signal is provided to the power supply input.