| dc.description.abstract | Several low noise amplifiers and mixers used in microwave and millimeter-wave radio front-end receiver are presented in this thesis. A broadband single-ended mixer using 0.18 μm SiGe BiCMOS process is presented in Chapter 2. A hybrid modified NMOS-HBT Darlington cell is proposed for the circuit design. The bandwidth and conversion are further improved as compared to the conventional Darlington cell mixer. The mixer exhibits a broad RF bandwidth of from 25 to 70 GHz with a lower driving LO power of 2 dBm, a maximum conversion gain of 5 dB. Moreover, this work has the best figure of merit, and the mixer can be performed a broadband digital demodulator with a data rate of up to 2 Gbps.
Four Gilbert-cell mixers are implemented in GaAs 2 μm heterojunction bipolar transistor (HBT) and 0.5 μm high electron mobility transistor (HEMT) process are presented in Chapter 3. These Gilbert-cell mixers employ an inductive peaking technique to improve the high frequency response. The switch stage and the transconductance stage are designed using variable transistor combinations to enhance the conversion gain and bandwidth. Among these configurations, the HBT-HEMT Gilbert-cell mixer exhibits the best gain-bandwidth product and the widest bandwidth. Moreover, an IQ mixer is developed using the HBT-HEMT Gilbert-cell mixer, a power divider, and a 90。Hybrid couplers. For the QPSK demodulation, the measured error vector magnitude (EVM) is less than 7.4%. The measured eye diagram is evaluated up to 2.5 Gbps.
Two Q-band low noise amplifiers using 0.15 μm GaAs pHEMT (LNA1) and 0.1 μm GaAs pHEMT (LNA2) process for broadband communication and radio astronomy applications are presented in Chapter 4. Between 21.8 and 45.5 GHz, the LNA1 features a small signal gain of higher than 19.5 dB, a minimum noise figure of 2.3 dB at 37 GHz, and a gain-bandwidth product (GBPA) of 266 GHz. Between 26.8 and 50.4 GHz, the LNA2 features a small signal gain of higher than 21.6 dB, a minimum noise figure of 2.8 dB at 36 GHz, and a GBPA of 395 GHz. The chip sizes of the LNA1 and LNA2 are both 2×1 mm2. The LNAs demonstrate broad bandwidth, high gain, low noise figure, and compact chip size. Moreover, this work demonstrates the highest GBPA among all the reported Q-band LNAs.
Finally, the conclusions and future works are addressed in Chapter 5. | en_US |