(A) wideband 120 GHz CMOS transmitter for short-range high-speed wireless communication

Abstract

With advances in semiconductor process technology and circuit design technology in millimeter-wave, data transmission at the level of tens of Gbps has become possible, and many applications requiring high-speed data interconnection between devices or chips have emerged. Accordingly, broadband transceivers aimed at high-speed data transmission have been developed, and efforts are being made to use a higher-order modulation scheme to increase data rate.However, as the higher-order modulation method is used, the required signal-to-noise ratio (SNR) also increases, which puts a great burden on circuit design. In fact, the previously reported transceivers consume a lot of power or have limitations in terms of LO circuit or antenna integration. This paper introduces an RF front-end system link for short-range high-speed wireless communication that can overcome these problems, and propose a wideband 120 GHz CMOS transmitter.The single channel RF front-end aims to achieve a data rate of 50 Gbps at a communication distance of 10 cm by using a 16-quadrature amplitude modulation (QAM) method, and a 30 GHz bandwidth at a center frequency of 120 GHz.The target application is chip-to-chip (C2C) or device-to-device (D2D) communication, and in particular, the polarization direction is controlled using dual-polarization considering the case where the transmitter and receiver are not fixed, such as D2D communication. The transmitter consists of an I/Q modulator for 16-QAM communication, a power amplifier (PA), a phase shifter (P/S) and a variable-gain amplifier (VGA) to control the polarization direction, and is designed using a CMOS 40nm process. The integrated transmitter was packaged with a dual-polarization antenna, and the dual-polarization performance and 16-QAM communication performance were verified through this packaged module. This paper is composed of a total of 6 chapters. First, Chapter 1 explains the motivation of the research and the trends of existing studies, and calculates the system parameters of RF front-end to achieve the target data rate of 50 Gbps. Prior to the circuit design, Chapter 2 describes the system signal-to-noise ratio (SNR) required for 16-QAM communication, and explains the system link budget of the RF front-end. In addition, it also describes the P/S and VGA requirement for dual-polarization control. In Chapter 3, the sub-blocks of the transmitter are described in earnest. The design process and main ideas of up-converter, P/S, and VGA are explained, and measurement results are analyzed. Chapter 4 presents the integrated transmitter. It describes the measurement results of sub-integration and fully-integrated transmitters, and presents the performance of dual-polarization. Chapter 5 describes the setup and results of 16-QAM communication experiments measured using packaged transmitter module with antenna. Lastly, Chapter 6 will summarize the paper.