High-speed Circuit Blocks for Radar and Optical Communication Systems

• Main Authors: Tu, Chia-Hou, 涂家豪
• Other Authors: Hsu, Shuo-Hung
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/36860963557133038758

碩士 === 國立清華大學 === 電子工程研究所 === 99 === As the technology improves, circuits fabricated on CMOS can have faster operation speed. This provides a great opportunity to realize high speed communication systems on CMOS. In this work we focus on circuits designed for high speed applications, and propose several techniques to conquer problems when designing these circuits. For wireless communication, this thesis is focused on 79 GHz automotive pulse radar application, and several circuit blocks are presented. First, to prevent signals from interrupting other cars' signals, coding technique is adopted, so there needs to be a BPSK modulator designed for coding function. Second, injection-locked VCO is used to solve harmonic problems resulting from original self-tripling VCO. It serves as an active filter and can provide a clean LO source. Programmable gain amplifier is also proposed in this thesis. It provides various gains when the radar echo signals have different signal strength. Complete 79 GHz automotive pulse radar transmitter is also shown in this work. It consists of a programmable pulse generator, a voltage controlled oscillator, a BPSK modulator, a driving amplifier, and a balun. It can transmit modulated signals including OOK, BPSK, and FMCW. For optical communication system, since the parasitic capacitance from the photodiode degrades bandwidth performance, the system needs a low input impedance transimpedance amplifier to relieve this parasitics' effect. Based on conventional regulated cascode (RGC) structure, we designed and analyzed two modified transimpedance amplifiers (TIA). The first transimepdance amplifier solves the voltage headroom problem caused by cascode structure while the second transimpedance amplifier employs capacitive peaking technique to enhance circuit bandwidth.