Tian-zuo Xi | Southern Methodist University (original) (raw)

Papers by Tian-zuo Xi

2014 IEEE Radio Frequency Integrated Circuits Symposium, 2014

This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave ... more This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave Quadrature VCO (QVCO) and VCOs. A transformer coupling with extra phase shift is proposed in QVCO to decouple the tradeoff between phase noise (PN) and phase error and improve the PN performance. This technique is demonstrated in a mmWave QVCO with a measured PN of-119.2dBc/Hz at 10MHz offset of a 56.2GHz carrier and a tuning range of 9.1% (FOM T of-179dBc/Hz). To our best knowledge, this QVCO has the lowest PN at 10MHz offset among all the QVCOs around 50-60GHz frequency range. In addition, an inductive divider feedback technique is proposed in VCO design to improve the transconductance linearity, resulting in larger signal swing and lower PN compared to the conventional LC VCOs. The effectiveness of this approach is demonstrated in a 76GHz VCO and a 90GHz VCO, both fabricated in a 65nm CMOS process, with an FOM T of 173.6dBc/Hz and 173.1dBc/Hz, respectively.

2014 IEEE Asian Solid-State Circuits Conference (A-SSCC), 2014

This paper presents a novel topology of lownoise amplifier (LNA) with noise reduction and gain im... more This paper presents a novel topology of lownoise amplifier (LNA) with noise reduction and gain improvement. A transformer feedback g m-boosting technique is proposed in a single-ended cascode LNA to reduce the noise figure (NF) and improve the gain simultaneously. Two 54 GHz single-ended cascode LNAs, with transformer and transmission-line for matching, respectively, are demonstrated to verify this technique. Fabricated in a 65 nm CMOS process, the transformer-based (TF-based) LNA exhibits a minimum noise figure (NF) of 3.6 dB at 53.5 GHz and a highest power gain of 28.2 dB at 54 GHz in measurement. To our best knowledge, this LNA has the best noise figure and power gain among all the published V-band CMOS LNAs. The transmission-line-based (TL-based) LNA exhibits a minimum noise figure of 3.8 dB at 53.9 GHz and a highest power gain of 25.4 dB at 54.2 GHz in measurement. Both the LNAs consume 18 mA from a power supply of 1.1 V.

2015 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), 2015

A low-power CMOS mmWave passive mixer based on a novel LO shaping technique using non-linear tran... more A low-power CMOS mmWave passive mixer based on a novel LO shaping technique using non-linear transmission line (NLTL) is proposed. The mixer employs a non-return-to-zero (NRZ) capacitive loaded sampling structure. The LO signal is reshaped by an NLTL before it is applied to the mixer, which alleviates the tradeoff between the mixer gain and linearity and decreases the noise figure (NF). The NLTL is constructed using series inductors and shunt varactors. It boosts the LO swing and re-shapes the LO pulses to have higher amplitude, narrower pulses, and sharper edges, resulting in higher gain, better linearity, and lower noise figure. Two mixers, one operated at 60GHz and the other at 120GHz, are designed using 65nm CMOS process. The simulation results show single-sideband NF of 5.9dB and 6.8dB, IP1dB of 0.9dBm and 1.4dBm, and a power gain of 1.2dB and 1dB, for the 60GHz and 120GHz mixers, respectively. Both mixers require a 0dBm LO input level and do not consume DC power.

2015 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), 2015

2014 IEEE Radio Frequency Integrated Circuits Symposium, 2014

This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave ... more This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave Quadrature VCO (QVCO) and VCOs. A transformer coupling with extra phase shift is proposed in QVCO to decouple the tradeoff between phase noise (PN) and phase error and improve the PN performance. This technique is demonstrated in a mmWave QVCO with a measured PN of -119.2dBc/Hz at 10MHz offset of a 56.2GHz carrier and a tuning range of 9.1% (FOM T of -179dBc/Hz). To our best knowledge, this QVCO has the lowest PN at 10MHz offset among all the QVCOs around 50-60GHz frequency range. In addition, an inductive divider feedback technique is proposed in VCO design to improve the transconductance linearity, resulting in larger signal swing and lower PN compared to the conventional LC VCOs. The effectiveness of this approach is demonstrated in a 76GHz VCO and a 90GHz VCO, both fabricated in a 65nm CMOS process, with an FOM T of 173.6dBc/Hz and 173.1dBc/Hz, respectively. Index Terms -VCO, quadrature VCO (QVCO), phase noise, transformer, transconductance linearization.

2014 IEEE Asian Solid-State Circuits Conference (A-SSCC), 2014

2014 IEEE Radio Frequency Integrated Circuits Symposium, 2014

This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave ... more This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave Quadrature VCO (QVCO) and VCOs. A transformer coupling with extra phase shift is proposed in QVCO to decouple the tradeoff between phase noise (PN) and phase error and improve the PN performance. This technique is demonstrated in a mmWave QVCO with a measured PN of-119.2dBc/Hz at 10MHz offset of a 56.2GHz carrier and a tuning range of 9.1% (FOM T of-179dBc/Hz). To our best knowledge, this QVCO has the lowest PN at 10MHz offset among all the QVCOs around 50-60GHz frequency range. In addition, an inductive divider feedback technique is proposed in VCO design to improve the transconductance linearity, resulting in larger signal swing and lower PN compared to the conventional LC VCOs. The effectiveness of this approach is demonstrated in a 76GHz VCO and a 90GHz VCO, both fabricated in a 65nm CMOS process, with an FOM T of 173.6dBc/Hz and 173.1dBc/Hz, respectively.

2014 IEEE Asian Solid-State Circuits Conference (A-SSCC), 2014

This paper presents a novel topology of lownoise amplifier (LNA) with noise reduction and gain im... more This paper presents a novel topology of lownoise amplifier (LNA) with noise reduction and gain improvement. A transformer feedback g m-boosting technique is proposed in a single-ended cascode LNA to reduce the noise figure (NF) and improve the gain simultaneously. Two 54 GHz single-ended cascode LNAs, with transformer and transmission-line for matching, respectively, are demonstrated to verify this technique. Fabricated in a 65 nm CMOS process, the transformer-based (TF-based) LNA exhibits a minimum noise figure (NF) of 3.6 dB at 53.5 GHz and a highest power gain of 28.2 dB at 54 GHz in measurement. To our best knowledge, this LNA has the best noise figure and power gain among all the published V-band CMOS LNAs. The transmission-line-based (TL-based) LNA exhibits a minimum noise figure of 3.8 dB at 53.9 GHz and a highest power gain of 25.4 dB at 54.2 GHz in measurement. Both the LNAs consume 18 mA from a power supply of 1.1 V.

2015 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), 2015

A low-power CMOS mmWave passive mixer based on a novel LO shaping technique using non-linear tran... more A low-power CMOS mmWave passive mixer based on a novel LO shaping technique using non-linear transmission line (NLTL) is proposed. The mixer employs a non-return-to-zero (NRZ) capacitive loaded sampling structure. The LO signal is reshaped by an NLTL before it is applied to the mixer, which alleviates the tradeoff between the mixer gain and linearity and decreases the noise figure (NF). The NLTL is constructed using series inductors and shunt varactors. It boosts the LO swing and re-shapes the LO pulses to have higher amplitude, narrower pulses, and sharper edges, resulting in higher gain, better linearity, and lower noise figure. Two mixers, one operated at 60GHz and the other at 120GHz, are designed using 65nm CMOS process. The simulation results show single-sideband NF of 5.9dB and 6.8dB, IP1dB of 0.9dBm and 1.4dBm, and a power gain of 1.2dB and 1dB, for the 60GHz and 120GHz mixers, respectively. Both mixers require a 0dBm LO input level and do not consume DC power.

2015 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), 2015

2014 IEEE Radio Frequency Integrated Circuits Symposium, 2014

This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave ... more This paper presents new circuit topologies and design techniques for low-phase-noise CMOS mmWave Quadrature VCO (QVCO) and VCOs. A transformer coupling with extra phase shift is proposed in QVCO to decouple the tradeoff between phase noise (PN) and phase error and improve the PN performance. This technique is demonstrated in a mmWave QVCO with a measured PN of -119.2dBc/Hz at 10MHz offset of a 56.2GHz carrier and a tuning range of 9.1% (FOM T of -179dBc/Hz). To our best knowledge, this QVCO has the lowest PN at 10MHz offset among all the QVCOs around 50-60GHz frequency range. In addition, an inductive divider feedback technique is proposed in VCO design to improve the transconductance linearity, resulting in larger signal swing and lower PN compared to the conventional LC VCOs. The effectiveness of this approach is demonstrated in a 76GHz VCO and a 90GHz VCO, both fabricated in a 65nm CMOS process, with an FOM T of 173.6dBc/Hz and 173.1dBc/Hz, respectively. Index Terms -VCO, quadrature VCO (QVCO), phase noise, transformer, transconductance linearization.

2014 IEEE Asian Solid-State Circuits Conference (A-SSCC), 2014