Design of Synthetic Quasi-TEM Transmission-Line-Based CMOS Transceiver for Implementation of FMCW Radar System
Date Issued
2009
Date
2009
Author(s)
Wang, Sen
Abstract
This dissertation focuses on the analysis of a frequency-modulation continuous-wave (FMCW) system and the design of X-band FMCW transceiver in a standard 0.18-um CMOS technology. The single-chip transceivers are implemented by the presented complementary-conducting-strip transmission line (CCS TL) to miniaturize passive components which consume most chip area of RF circuits. The meandered CCS TL demonstrates its capability of miniaturization while maintains good isolation on the silicon substrate. Firstly, an overview of FMCW systems and modulation methods are discussed. Moreover, behavior models of the FMCW system are built in AgilentTM ADS simulator for system-level simulations. The proposed PLL-based architecture for FMCW applications is also investigated. The functions and relations among system parameters can be characterized from the simulations which provide designers with the system evaluation. econdly, the CCS TL-based passive components and active circuits are presented in chapter 3 and chapter 4, respectively. The area-consuming TLs and inductors of the RFICs are implemented by the meandered CCS TLs. The miniaturized designs such as the 90° hybrid and the rat-race hybrid demonstrate 95 % and 98 % size reduction compared to the prototype designs, respectively. Moreover, the VCO with frequency-modulation capability is investigated, and the modulation bandwidth is up to 400 MHz which could improve the range resolution in a radar system. Finally, the active BPF, SPDT switch and amplifiers realized by meandered CCS TLs implemented for miniaturization of resonators and matching networks, respectively. The active BPF achieves 0-dB passband loss with 4.5-mW power. hirdly, an electromagnetic (EM) model is proposed for investigating the couplings on the silicon substrate in chapter 5. Such EM model, which invokes the large-scale field analyses, can make a quantitative assessment of the EM couplings and can be applied into the system simulations for designing the CMOS FMCW transceiver. Furthermore, the model is applied to validate the effectiveness of the chip-scale leakage suppression by incorporating the CCS TL. The system simulations, which are performed with the proposed EM model, compared with those of the experimental results, showing a slight difference of 2.6 dB on the prediction of the isolation improvement. inally, two X-band CMOS single-chip transceivers are implemented in a standard 0.18-um CMOS technology, which incorporate the CCS TL-based components and circuits mentioned above. The first transceiver is for conventional FMCW radar applications. This transceiver, antennas and digital circuitry are integrated into a radar sensor. Moreover, the functionality of the radar sensor is verified experimentally. The second transceiver characterized in chapter 6, is developed for monopulse FMCW radar applications. The monopulse and quadrature transceiver integrates 16 building blocks with a chip area of 2.6 mm x 3.3 mm. The total power consumption of the transceiver is 0.35 W. The output power of the transmitter is 1 dBm with a 35-dB 2nd harmonic suppression. Moreover, the on-chip isolations between T/R in this compact transceiver are more than 60 dB. The measured receiver gain and NF are -4.5 dB and 11.5 dB, respectively. Finally, the obtained I/Q signals demonstrate 0.6-dB amplitude imbalance and 7° phase imbalance. This chip is also the first 0.18-μm CMOS transceiver for monopulse FMCW radar applications in the world.
Subjects
Radar
CMOS
Transmission Line
Type
thesis
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