Design of On-Wafer Calibration Kit for Accurate Pyramid Probe Card-Based Surface Acoustic Wave Filter Measurements

To be fully deployed in high-throughput acoustic filter testing environment, pyramid probe cards require accurate characterization and deembedding techniques. This article presents a systematic design procedure for an on-wafer short-open-load-thru (SOLT) calibration kit on lithium niobate substrates for filter measurements using pyramid probe cards. First, the propagation velocity of the lithium niobate substrate is extracted from a transmission line measurement-based characterization methodology. Next, the coefficient of the Thru standard is calculated using the propagation velocity. A line-reflect-reflect-match (LRRM)-based self-calibration algorithm and the partially known standards can then be used to remove the errors associated with the pyramid probe card. The coefficients of the remaining standards of the on-wafer calibration kit are finally extracted by employing the calibrated probe card. As the test fixture itself is utilized to characterize the on-wafer calibration kit, the need of additional fixtures and measurements is eliminated. The effectiveness of the on-wafer calibration is validated by performing repeatable measurements of state-of-the-art filters fabricated on lithium niobate substrate and comparing with other calibration approaches such as port extension and off-wafer calibration using impedance standard substrate (ISS). We demonstrate that the on-wafer calibration kit offers comparable performance in terms of in-band loss and out-of-band rejection.

Automated summary

To fully utilize pyramid probe cards in high-throughput acoustic filter testing, accurate characterization and deembedding techniques are required. This article presents a systematic design procedure for an on-wafer short-open-load-thru (SOLT) calibration kit on lithium niobate substrates for filter measurements using pyramid probe cards. The effectiveness of the on-wafer calibration is validated by performing repeatable measurements of state-of-the-art filters fabricated on lithium niobate substrate and comparing with other calibration approaches.