Integrated Self-Healing for mm-Wave Power Amplifiers
Self-healing as a technique for improving performance and yield of millimeter-wave power amplifiers (PAs) against process variation and transistor mismatch, load impedance mismatch, and partial and total transistor failure is described and investigated. A 28-GHz PA is presented with three types of sensors, two types of actuators, data converters, and a digital algorithm block that are all integrated on a single chip to show the validity of the technique. Two algorithms are implemented to either maximize output power or to minimize dc power for a desired output power. Measurements from 20 chips show increased RF output power up to 3 dB or reduced dc power by 50% in backoff with a 50-Ω load. Self-healing with up to 4-1 voltage standing-wave ratio load impedance mismatch is verified and linear operation under nonconstant envelope modulation is shown to improve with healing. Self-healing after laser cutter induced transistor failure is verified and increases RF output power by up to 5.4 dB. The aggregate yield of the PA across several representative specifications is increased from 0% to 80% with self-healing.
© 2013 IEEE. Manuscript received October 23, 2012; revised January 11, 2013; accepted January 15, 2013. Date of publication February 13, 2013; date of current version March 07, 2013. This work was supported by the Air Force Research Laboratory. This paper is an expanded paper from the IEEE RFIC Symposium, Montreal, QC, Canada, June 17–19, 2012. The authors would like to thank Prof. A. Babakhani, Rice University, Houston, TX, USA (formerly with the California Institute of Technology) and A. Chang, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA (formerly with the California Institute of Technology), for their valuable technical discussions and contributions, as well as Dr. S. Raman, Defense Advanced Research Projects Agency (DARPA), Arlington, VA, USA, T. Quach, Air Force Research Laboratory (AFRL), Dayton, OH, USA, and C. Maxey, Booz Allen Hamilton (BAH), McLean, VA, USA, for support. The views expressed are those of the authors and do not reflect the official policy of the Department of Defense (DoD) or the U.S. Government.