Capacitively Loaded Inverted CPWs for Distributed TRL-Based De-Embedding at (Sub) mm-Waves

Luca Galatro, Andreas Pawlak, Michael Schroter, Marco Spirito

Research output: Contribution to journalArticleScientificpeer-review

24 Citations (Scopus)


In this paper, we present a thru-reflect-line (TRL) calibration/de-embedding kit integrated in the back-end-of-line of a SiGe technology, which allows direct calibration at the first metallization layer, thus moving the reference planes as close as possible to the intrinsic device. The proposed calibration/ de-embedding kit features capacitively loaded inverted CPW lines, allowing to reduce the losses arising from the conducting (i.e., silicon) substrate, by confining the propagating field in the low-loss dielectric layers. The structures have been designed specifically for (sub) mm-wave measurements, as complementary to conventional de-embedding kits used at lower frequencies. A simplified analytical model is presented to support the design of the capacitively loaded CPW lines. Results of a calibration/de-embedding kit, realized using a 130-nm BiCMOS technology are experimentally obtained in the WR-03 waveguide band. Worst case error bounds providing error below 5% in the entire WR3 band are demonstrated. Comparison between direct calibration and de-embedding using calibration transfer from fused silica are provided to highlight the improvements of the proposed approach in the mm-wave bands. Finally, the TRL calibration kit is employed for S-parameter measurements of a heterojunction bipolar transistor and the results are compared to the HiCUM model of the same transistor for verification
Original languageEnglish
Pages (from-to)4914-4924
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number12
Publication statusPublished - 2017


  • Calibration
  • Coplanar waveguides
  • Dielectrics
  • Impedance
  • Power transmission lines
  • Substrates
  • Transmission line measurements
  • CPW
  • VNA.
  • distributed de-embedding
  • millimeter waves
  • silicon
  • slow wave
  • thru-reflect line (TRL)


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