A novel CMOS hexaferrite circulator with 25 GHz operating frequency

Guangjun Zhang,Yanfeng Jiang

doi:10.1063/5.0028225

Abstract

A novel CMOS hexaferrite circulator with a Y-junction structure is designed and fabricated, which is compatible with standard CMOS technology. The spin-coating approach is adopted during the fabrication, in which the photoresist is mixed with nano-hexaferrite powder for preparation of a magnetic thin film in the device. Compared with the traditional circulator with an external permanent magnet for operation, the novel circulator can utilize the spin-coating magnetic film and is compatible with CMOS technology. The remanent magnetization of the adopted hexaferrite thin film can provide the required magnetic field for reciprocity properties. The optimization of impedance matching and the improvements in the related parameters are demonstrated on the novel CMOS circulator. The CMOS circulator exhibits the merits of small volume and easy integration while keeping its promising non-reciprocity properties. The fabrication is conducted based on the standard 180-nm CMOS technology. S-parameter measurements on the circulator show that the device has an isolation of 20 dB over 520 MHz bandwidth at 26.2 GHz. The minimum insertion loss is 1.81 dB. The novel CMOS-compatible circulator has potential application in 5G wireless communication systems.

Highlights

The circulator is one of the most widely used microwave components in the electrical engineering field with promising nonreciprocity properties
The hexaferrite materials become a better option for the miniaturization of the circulator
The results show that the insertion loss and the isolation are 1.81 dB and 23.89 dB, respectively, with 520 MHz BW at the center frequency of 26.2 GHz

Summary

INTRODUCTION

The circulator is one of the most widely used microwave components in the electrical engineering field with promising nonreciprocity properties. Despite the higher insertion loss, the hexaferrite circulator shows compact volume and light weight In this manner, the hexaferrite circulator could be one of the promising candidates for the microwave integrated circuits. A novel approach for fabrication of the hexaferrite circulator with the standard CMOS technology is proposed in this paper. A circulator without the magnetic pole was proposed very recently, such as the magnetic-free passive circulator based on the N-path-filter and the active circulator based on temporal modulation in a 45-nm SOI CMOS.6 These circulators can realize the non-reciprocal properties using the specific circuit configuration without ferrite and can be integrated in the CMOS technology. A novel circulator is proposed and designed, which is completely compatible with the CMOS technology and can be operated up to 25 GHz. A spin-coating approach is adopted for magnetic layer preparation.

NOVEL APPROACH FOR MAGNETIC CYLINDER FABRICATION ON SILICON SUBSTRATE

CMOS CIRCULATOR DESIGN

RESULTS AND DISCUSSION

CONCLUSION