Jerry Lopez

... Van Li*, Jerry Lopez and Donald Y. Lie Department ofElectrical and Computer Engineering Texas Tech University Lubbock, TX 79409, USA *E-mail: yan.li@ttu.edu ... SPICE simulations using IBM SiGe7HP design kit with Cadence Spectre RF were RFin __-----J'----1 ...

This paper presents highly-efficient RF polar transmitter (TX) systems that utilize the envelope-tacking (ET) technique with monolithic SiGe power amplifiers (PAs) for mobile WiMAX and 3GPP Long Term Evolution (LTE) applications. Monolithic single-ended cascode SiGe PA design capable of enhancing its power-added efficiency (PAE) is demonstrated. Four RF switches are adopted at the bases of the common-emitter transistors, which can be turned on/off in response to the desired output power. We found that self-biasing of the common-base device with ET can improve the output distortion of the cascode PA to output 18dBm and passing the stringent mobile WiMAX linearity specs with 30% PAE at 2.3GHz without predistortion. Furthermore, a differential cascode SiGe PA using the proposed ET-based polar TX system can improve the average output power to 21dBm with 33.6% PAE at 1.42 GHz, and it also passes the stringent LTE 16QAM linearity specs without needing predistortion.

... K. Chen, S. Wu, T.-Y. Yang, and G.-K. Ma are with the SoC Technology Center, Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan. ... 2281 Fig. 7. System simulation block diagram that enables RF/analog and digital circuits co-design for the overall ET/EER ...

... K. Chen, S. Wu, T.-Y. Yang, and G.-K. Ma are with the SoC Technology Center, Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan. ... 2281 Fig. 7. System simulation block diagram that enables RF/analog and digital circuits co-design for the overall ET/EER ...

In this paper, a monolithic RF cascode SiGe power amplifier (PA) design capable of enhancing its power-added efficiency (PAE) is demonstrated. Four RF switches are adopted at the bases of the common-emitter transistors, which can be turned on/off in response to the desired output power. Simulations show that by utilizing device size variation, our cascode PA achieves higher gain and PAE compared to conventional fixed-size cascode PA in the low power region; in addition, it also provides more output power and higher average PAE than single-stage common-emitter PAs. We also studied and compared the linearity performance of our cascode PAs vs. single-stage common-emitter PAs in a RF polar TX using an envelope tracking (ET) technique. We found that even through self-biasing for the common-base device can improve the output distortion of cascode PAs, a single-stage common-emitter SiGe PA designed for comparison is still considerably more linear than cascode PAs. Therefore, more careful system linearization design will be critical when the cascode PAs are adopted in RF polar transmitters (TXs), especially for broadband wireless applications such as mobile WiMAX studied here.

... K. Chen, S. Wu, T.-Y. Yang, and G.-K. Ma are with the SoC Technology Center, Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan. ... 2281 Fig. 7. System simulation block diagram that enables RF/analog and digital circuits co-design for the overall ET/EER ...

In this paper, we report both circuits design and system simulations using highly-efficient monolithic SiGe class-E power amplifier (PA) with an open-loop envelope tracking (ET) technique for mobile WiMAX/Wibro applications. The 1-stage and 2-stage class-E PAs were designed and fabricated in a 0.18 mum BiCMOS SiGe technology. The 1-stage class-E PA achieved peak power added efficiency (PAE) of 62% at output power of 21 dBm in single-tone measurement. The design of linear-assisted switching envelope amplifier is also discussed, which involves balancing the tradeoff between efficiency and signal fidelity. Detailed co-design system simulations including RF circuits and digital DSP blocks show that our class-E PA can be linearized by the open-loop ET technique, and the entire ET-based transmit (TX) system meets the stringent 802.16e TX mask with ~33% overall average efficiency at output power of 18.5 dBm.

This paper presents a large-signal envelope-tracking (ET) polar transmitter (TX) system with a monolithic cascode SiGe power amplifier (PA) for mobile WiMAX applications. The envelope amplifiers are designed in the TSMC 0.35μm SiGe BiCMOS technology and also with discrete components for comparisons. The entire polar TX system using the discrete envelope amplifier in measurement achieves the power-added efficiency (PAE) of 30% at the average output power of 18 dBm with the EVM of 5% for WiMAX 64QAM 10 MHz signal. The RF/analog/digital co-simulations of the entire polar TX system with the integrated CMOS envelope amplifier show similar linearity and efficiency performances when compared with the measurement results. Both the simulation and measurement data suggests our polar TX design achieves the highest PAE among the state-of-the-art Si-based OFDM polar TX systems reported in the literature.

An intelligent non-contact wireless patient monitoring system is presented in this paper. The monitoring system is capable of measuring the vital signs (respiration rate and heart beat) and detecting patients' motion without physically contacting them by using a miniature Doppler radar sensor system. The system can provide all-round near-real-time 24/7 monitoring, which can be used in hospitals and homes to

A portable non-contact vital signs sensor system that is capable of continuously monitoring heart and respiration rates is presented. The system operates based on the continuous wave (CW) Doppler radar principle and has been evaluated using several antenna types: patch, Yagi, log-periodic and helical. The sensor operates at 2.4 GHz, realized on a custom designed low-cost PCB that integrates both the RF receiver (Rx) and transmitter (Tx) sections with analog electronics. It uses a quadrature receiver architecture with separate Tx and Rx antennas. The sensor using our custom designed helical antenna performs best among all antennas tested here. The sensor system can achieve a ±1 beat/min error versus the reference heartbeat signal for 75% of the continuous monitoring time, while the accuracy for the respiration rate is within ±1 breath/min for 95% of the time.

An Axial-Mode Helical Antenna (AMHA) design for applications in Doppler-based continuous non-contact vital signs (NCVS) monitoring sensor systems is presented. Two methodologies of on-reflector impedance matching are presented as a solution to the helical antennas' non-50Ω input impedance issue. The antennas are evaluated on their performance of VSWR, impedance, radiation pattern directivity, size and gain. A size reduction design process is given for custom sizing the helical antenna, and the resulting structures are compared versus a patch antenna at 2.4GHz that is often used in NCVS systems. Our test data indicates that an AMHA can significantly increase accuracy of NCVS systems by increasing the system's Signal-to-Noise-and-Interference Ratio (SNIR).

An intelligent non-contact wireless patient monitoring system is presented in this paper. The monitoring system is capable of measuring the vital signs (respiration rate and heart beat) and detecting patients' motion without physically contacting them by using a miniature Doppler radar sensor system. The system can provide all-round near-real-time 24/7 monitoring, which can be used in hospitals and homes to

A portable non-contact vital signs sensor system that is capable of continuously monitoring heart and respiration rates is presented. The system operates based on the continuous wave (CW) Doppler radar principle and has been evaluated using several antenna types: patch, Yagi, log-periodic and helical. The sensor operates at 2.4 GHz, realized on a custom designed low-cost PCB that integrates both the RF receiver (Rx) and transmitter (Tx) sections with analog electronics. It uses a quadrature receiver architecture with separate Tx and Rx antennas. The sensor using our custom designed helical antenna performs best among all antennas tested here. The sensor system can achieve a ±1 beat/min error versus the reference heartbeat signal for 75% of the continuous monitoring time, while the accuracy for the respiration rate is within ±1 breath/min for 95% of the time.

An Axial-Mode Helical Antenna (AMHA) design for applications in Doppler-based continuous non-contact vital signs (NCVS) monitoring sensor systems is presented. Two methodologies of on-reflector impedance matching are presented as a solution to the helical antennas' non-50Ω input impedance issue. The antennas are evaluated on their performance of VSWR, impedance, radiation pattern directivity, size and gain. A size reduction design process is given for custom sizing the helical antenna, and the resulting structures are compared versus a patch antenna at 2.4GHz that is often used in NCVS systems. Our test data indicates that an AMHA can significantly increase accuracy of NCVS systems by increasing the system's Signal-to-Noise-and-Interference Ratio (SNIR).

An intelligent non-contact wireless patient monitoring system is presented in this paper. The monitoring system is capable of measuring the vital signs (respiration rate and heart beat) and detecting patients' motion without physically contacting them by using a miniature Doppler radar sensor system. The system can provide all-round near-real-time 24/7 monitoring, which can be used in hospitals and homes to

A portable non-contact vital signs sensor system that is capable of continuously monitoring heart and respiration rates is presented. The system operates based on the continuous wave (CW) Doppler radar principle and has been evaluated using several antenna types: patch, Yagi, log-periodic and helical. The sensor operates at 2.4 GHz, realized on a custom designed low-cost PCB that integrates both the RF receiver (Rx) and transmitter (Tx) sections with analog electronics. It uses a quadrature receiver architecture with separate Tx and Rx antennas. The sensor using our custom designed helical antenna performs best among all antennas tested here. The sensor system can achieve a ±1 beat/min error versus the reference heartbeat signal for 75% of the continuous monitoring time, while the accuracy for the respiration rate is within ±1 breath/min for 95% of the time.

An Axial-Mode Helical Antenna (AMHA) design for applications in Doppler-based continuous non-contact vital signs (NCVS) monitoring sensor systems is presented. Two methodologies of on-reflector impedance matching are presented as a solution to the helical antennas' non-50Ω input impedance issue. The antennas are evaluated on their performance of VSWR, impedance, radiation pattern directivity, size and gain. A size reduction design process is given for custom sizing the helical antenna, and the resulting structures are compared versus a patch antenna at 2.4GHz that is often used in NCVS systems. Our test data indicates that an AMHA can significantly increase accuracy of NCVS systems by increasing the system's Signal-to-Noise-and-Interference Ratio (SNIR).