Digitally-Controlled Compensation Current Injection to ATE Power Supply for Emulation of Customer Environment

Mismatch of power supply integrity of power delivery network (PDN) between an automatic test equipment (ATE) and a customer board can lead to test failures such as overkills or underkills during semiconductor test. This paper proposes a technique to control the power supply impedance on an ATE using compensation current injection so that it emulates the impedance on a customer board. Digital filter is used to calculate compensation current waveform in real time in response to the measured power supply voltage fluctuation. Its implementation is based on the PDNs of both the ATE and the customer board. This paper introduces the filter implementation methodology for arbitrary PDN using nested-feedback loop of digital filter, as well as experimental results of prototype circuits. This paper demonstrates that with the proposed current injection the power supply voltage fluctuation waveform on the ATE matches up with that on the customer board, which means that the compensation current injection successfully controls and emulates the impedance. With the proposed technique test failures caused by the impedance difference between the two environments are reduced.