Content area
Full Text
ABSTRACT: In this paper, a variable gain phase shifter is developed using 180 nm CMOS process at S-band, which can control phase and gain independently. This has a potential application in a conformal phased array antenna, for beamforming within 360° range. The integrated phase shifter, along with the variable gain amplifier, helps in recovering the degraded radiation pattern precisely due to the conformal shaping of the antenna. The simulation results show state-of-the-art performances of 7dB conversion gain with variable gain and a continuous phase rotation of 360°. The fabricated chip, measuring an area of 1.125 mm2, consumes a very low power of 17 mW.
1INTRODUCTION
Phased array antenna systems can be used for wireless communication during space explorations where the antenna array can be placed on the suits of the astronauts. But due to movement of the astronauts, the radiation pattern of the antenna changes. A phase shifter can be used in this case to recover the degradation of the radiation pattern, by providing the required amount of phase shifts to each of the antenna array elements (Braaten, et al. 2013). There are several classifications of phase shifters, like passive phase shifters, active phase shifters (Vadivelu, Praveen Babu, et al. 2009), analog and digital phase shifters (Nagra, Amit S., et al. 1999), switched line phase shifters (Kang, DongWoo, et al. 2006), loaded-line phase shifters (Yu, Yikun, et al. 2008), and reflection type phase shifters (Malczewski, A., et al. 1999) among others.
Now a days, it is possible to integrate a high number of transistors into a single chip, with the transistors exhibiting both analog and digital functionality (Masaki, Ichiro, et al. 1995). The realization of System-On-Chip (SOC) solutions was possible using CMOS RFIC (Radio Frequency Integrated Circuits), where both analog and digital functionality can be integrated into a single process platform and where the digital circuitry can control analog radio with computer programs.
In our work, we have designed and fabricated a CMOS phase shifter, which is to be operated at the S frequency band. There are several circuits, which are integrated together in a single chip to create the variable gain phase shifter as shown in Fig. 1 are a passive hybrid, two active baluns, a double balanced Gilbert Cell, two...