Integration of GMR-based spin torque oscillators and CMOS circuitry

Abstract

This paper demonstrates the integration of giant magnetoresistance (GMR) spin torque oscillators (STO) with dedicated high frequency CMOS circuits. The wire-bonding-based integration approach is employed in this work, since it allows easy implementation, measurement and replacement. A GMR STO is wire-bonded to the dedicated CMOS integrated circuit (IC) mounted on a PCB, forming a (GMR STO+CMOS IC) pair. The GMR STO has a lateral size of 70nm and more than an octave of tunability in the microwave frequency range. The proposed CMOS IC provides the necessary bias-tee for the GMR STO, as well as electrostatic discharge (ESD) protection and wideband amplification targeting high frequency GMR STO-based applications. It is implemented in a 65nm CMOS process, offers a measured gain of 12dB, while consuming only 14.3mW and taking a total silicon area of 0.329mm2. The measurement results show that the (GMR STO+CMOS IC) pair has a wide tunability range from 8GHz to 16.5GHz and improves the output power of the GMR STO by about 10dB. This GMR STO–CMOS integration eliminates wave reflections during the signal transmission and therefore exhibits good potential for developing high frequency GMR STO-based applications, which combine the features of CMOS and STO technologies.