Analysis, Design, Modeling, and Characterization of Low-Loss Scalable On-Chip Transformers

A few important design choices for a low-loss scalable on-chip transformer are discussed, the most important one being that the capacitive and inductive couplings should be aligned to minimize insertion loss. The importance of these design choices is illustrated both theoretically as well as experimentally. In particular, for the first time the performance of these on-chip transformers is verified with four-port S -parameter measurements taken up to 67 GHz. With that, an insertion loss of only 0.6 dB up to 30 GHz is demonstrated. To facilitate the use of these low-loss on-chip transformers in the RF integrated-circuit design flow, a scalable compact equivalent-circuit model suitable for all pre-layout circuit simulations is described, which accurately predicts transformation ratios, transmission efficiencies and balun amplitude and phase imbalances.

[1]  L.F. Tiemeijer,et al.  Physics-based wideband predictive compact model for inductors with high amounts of dummy metal fill , 2006, IEEE Transactions on Microwave Theory and Techniques.

[2]  S. Ramo,et al.  Fields and Waves in Communication Electronics , 1966 .

[3]  A. Gopinath,et al.  Variation of microstrip losses with thickness of strip , 1971 .

[4]  J.R. Long,et al.  Monolithic transformers for silicon RF IC design , 2000, IEEE Journal of Solid-State Circuits.

[5]  L.F. Tiemeijer,et al.  Predictive spiral inductor compact model for frequency and time domain , 2003, IEEE International Electron Devices Meeting 2003.

[6]  Chuan Wang,et al.  A Physics-Based Equivalent-Circuit Model for On-Chip Symmetric Transformers With Accurate Substrate Modeling , 2009, IEEE Transactions on Microwave Theory and Techniques.

[7]  C. Cismaru,et al.  Characterization, design, modeling, and model validation of silicon-wafer M:N balun components under matched and unmatched conditions , 2005, IEEE Journal of Solid-State Circuits.

[8]  J.R. Long,et al.  Design and Modeling of mm-Wave Monolithic Transformers , 2006, 2006 Bipolar/BiCMOS Circuits and Technology Meeting.

[9]  D. Belot,et al.  An Analytical Broadband Model for Millimeter-Wave Transformers in Silicon Technologies , 2012, IEEE Transactions on Electron Devices.

[10]  E. Kerherve,et al.  Modeling and Characterization of On-Chip Transformers for Silicon RFIC , 2007, IEEE Transactions on Microwave Theory and Techniques.

[11]  Ali M. Niknejad,et al.  Analysis, design, and optimization of spiral inductors and transformers for Si RF ICs , 1998, IEEE J. Solid State Circuits.

[12]  V. Tripathi.  Asymmetric Coupled Transmission Lines in an Inhomogeneous Medium , 1975 .

[13]  E. van der Heijden,et al.  Colpitts VCOs for low-phase noise and low-power applications with transformer-coupled tank , 2008, 2008 IEEE Radio Frequency Integrated Circuits Symposium.

[14]  Tao Liu,et al.  Scalable Compact Circuit Model for Differential Spiral Transformers in CMOS RFICs , 2006, IEEE Transactions on Electron Devices.

[15]  A. Niknejad,et al.  Analysis , Design , and Optimization of Spiral Inductors and Transformers for Si RF IC ’ s , 1998 .

[16]  Veysel Demir,et al.  Microstrip conductor loss models for electromagnetic analysis , 2003 .

[17]  T. Biondi,et al.  Analysis and modeling of layout scaling in silicon integrated stacked transformers , 2006, IEEE Transactions on Microwave Theory and Techniques.

[18]  Edwin van der Heijden,et al.  Two Multiport De-Embedding Methods for Accurate On-Wafer Characterization of 60-GHz Differential Amplifiers , 2011, IEEE Transactions on Microwave Theory and Techniques.

[19]  J. R. Long,et al.  Modeling of monolithic inductors and transformers for silicon RFIC design , 1995, Proceedings of 1995 IEEE MTT-S International Topical Symposium on Technologies for Wireless Applications (Conjunction with INTER COMM'95).

[20]  J. Burghartz,et al.  Substrate effects in monolithic RF transformers on silicon , 2002 .