The Experts below are selected from a list of 12114 Experts worldwide ranked by ideXlab platform
Bram Nauta - One of the best experts on this subject based on the ideXlab platform.
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a polyphase multipath technique for software defined Radio Transmitters
IEEE Journal of Solid-state Circuits, 2006Co-Authors: Rameswor Shrestha, Eric A M Klumperink, E Mensink, Gerard J M Wienk, Bram NautaAbstract:Transmitter circuits using large signal swings and hard-switched mixers are power-efficient, but also produce unwanted harmonics and sidebands, which are commonly removed using dedicated filters. This paper presents a polyphase multipath technique to relax or eliminate filters by canceling a multitude of harmonics and sidebands. Using this technique, a wideband and flexible power upconverter with a clean output spectrum is realized in 0.13-mum CMOS, aiming at a software-defined Radio application. Prototype chips operate from DC to 2.4 GHz with spurs smaller than -40 dBc up to the 17th harmonic (18-path mode) or 5th harmonic (6-path mode) of the transmit frequency, without tuning or calibration. The transmitter delivers 8 mW of power to a 100-Omega load (2.54 Vpp-diff voltage swing) and the complete chip consumes 228 mW from a 1.2-V supply. It uses no filters, but only digital circuits and mixers
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a polyphase multipath technique for software defined Radio Transmitters
International Solid-State Circuits Conference, 2006Co-Authors: Rameswor Shrestha, Eric A M Klumperink, E Mensink, Gerard J M Wienk, Bram NautaAbstract:Transmitter circuits using large signal swings and hard-switched mixers are power-efficient, but also produce unwanted harmonics and sidebands, which are commonly removed using dedicated filters. This paper presents a polyphase multipath technique to relax or eliminate filters by canceling a multitude of harmonics and sidebands. Using this technique, a wideband and flexible power upconverter with a clean output spectrum is realized in 0.13-μm CMOS, aiming at a software-defined Radio application. Prototype chips operate from DC to 2.4 GHz with spurs smaller than -40 dBc up to the 17th harmonic (18-path mode) or 5th harmonic (6-path mode) of the transmit frequency, without tuning or calibration. The transmitter delivers 8 mW of power to a 100-Ω load (2.54 V pp-diff voltage swing) and the complete chip consumes 228 mW from a 1.2-V supply. It uses no filters, but only digital circuits and mixers.
S D Johnston - One of the best experts on this subject based on the ideXlab platform.
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measurement of bovine body and scrotal temperature using implanted temperature sensitive Radio Transmitters data loggers and infrared thermography
International Journal of Biometeorology, 2017Co-Authors: Andrea Wallage, J B Gaughan, A Lisle, L A Beard, C W Collins, S D JohnstonAbstract:Synchronous and continuous measurement of body (BT) and scrotal temperature (ST) without adverse welfare or behavioural interference is essential for understanding thermoregulation of the bull testis. This study compared three technologies for their efficacy for long-term measurement of the relationship between BT and ST by means of (1) temperature sensitive Radio Transmitters (RT), (2) data loggers (DL) and (3) infrared imaging (IRI). After an initial pilot study on two bulls to establish a surgical protocol, RTs and DLs were implanted into the flank and mid-scrotum of six Wagyu bulls for between 29 and 49 days. RT frequencies were scanned every 15 min, whilst DLs logged every 30 min. Infrared imaging of the body (flank) and scrotum of each bull was recorded hourly for one 24-h period and compared to RT and DL data. After a series of subsequent heat stress studies, bulls were castrated and testicular tissue samples processed for evidence of histopathology. Radio Transmitters were less reliable than DLs; RTs lost >11 % of data, whilst 11 of the 12 DLs had 0 % data loss. IRI was only interpretable in 35.8 % of images recorded. Pearson correlations between DL and RT were strong for both BT (r > 0.94, P 0.80, P < 0.001). Surgery produced temporary minor inflammation and scrotal hematoma in two animals post-surgery. Whilst scar tissue was observed at all surgical sutured sites when bulls were castrated, there was no evidence of testicular adhesion and normal active spermatogenesis was observed in six of the eight implanted testicles. There was no significant correlation of IRI with either DL or RT. We conclude that DLs provided to be a reliable continuous source of data for synchronous measurement of BT and ST.
Rameswor Shrestha - One of the best experts on this subject based on the ideXlab platform.
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a polyphase multipath technique for software defined Radio Transmitters
IEEE Journal of Solid-state Circuits, 2006Co-Authors: Rameswor Shrestha, Eric A M Klumperink, E Mensink, Gerard J M Wienk, Bram NautaAbstract:Transmitter circuits using large signal swings and hard-switched mixers are power-efficient, but also produce unwanted harmonics and sidebands, which are commonly removed using dedicated filters. This paper presents a polyphase multipath technique to relax or eliminate filters by canceling a multitude of harmonics and sidebands. Using this technique, a wideband and flexible power upconverter with a clean output spectrum is realized in 0.13-mum CMOS, aiming at a software-defined Radio application. Prototype chips operate from DC to 2.4 GHz with spurs smaller than -40 dBc up to the 17th harmonic (18-path mode) or 5th harmonic (6-path mode) of the transmit frequency, without tuning or calibration. The transmitter delivers 8 mW of power to a 100-Omega load (2.54 Vpp-diff voltage swing) and the complete chip consumes 228 mW from a 1.2-V supply. It uses no filters, but only digital circuits and mixers
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a polyphase multipath technique for software defined Radio Transmitters
International Solid-State Circuits Conference, 2006Co-Authors: Rameswor Shrestha, Eric A M Klumperink, E Mensink, Gerard J M Wienk, Bram NautaAbstract:Transmitter circuits using large signal swings and hard-switched mixers are power-efficient, but also produce unwanted harmonics and sidebands, which are commonly removed using dedicated filters. This paper presents a polyphase multipath technique to relax or eliminate filters by canceling a multitude of harmonics and sidebands. Using this technique, a wideband and flexible power upconverter with a clean output spectrum is realized in 0.13-μm CMOS, aiming at a software-defined Radio application. Prototype chips operate from DC to 2.4 GHz with spurs smaller than -40 dBc up to the 17th harmonic (18-path mode) or 5th harmonic (6-path mode) of the transmit frequency, without tuning or calibration. The transmitter delivers 8 mW of power to a 100-Ω load (2.54 V pp-diff voltage swing) and the complete chip consumes 228 mW from a 1.2-V supply. It uses no filters, but only digital circuits and mixers.
Andrea Wallage - One of the best experts on this subject based on the ideXlab platform.
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measurement of bovine body and scrotal temperature using implanted temperature sensitive Radio Transmitters data loggers and infrared thermography
International Journal of Biometeorology, 2017Co-Authors: Andrea Wallage, J B Gaughan, A Lisle, L A Beard, C W Collins, S D JohnstonAbstract:Synchronous and continuous measurement of body (BT) and scrotal temperature (ST) without adverse welfare or behavioural interference is essential for understanding thermoregulation of the bull testis. This study compared three technologies for their efficacy for long-term measurement of the relationship between BT and ST by means of (1) temperature sensitive Radio Transmitters (RT), (2) data loggers (DL) and (3) infrared imaging (IRI). After an initial pilot study on two bulls to establish a surgical protocol, RTs and DLs were implanted into the flank and mid-scrotum of six Wagyu bulls for between 29 and 49 days. RT frequencies were scanned every 15 min, whilst DLs logged every 30 min. Infrared imaging of the body (flank) and scrotum of each bull was recorded hourly for one 24-h period and compared to RT and DL data. After a series of subsequent heat stress studies, bulls were castrated and testicular tissue samples processed for evidence of histopathology. Radio Transmitters were less reliable than DLs; RTs lost >11 % of data, whilst 11 of the 12 DLs had 0 % data loss. IRI was only interpretable in 35.8 % of images recorded. Pearson correlations between DL and RT were strong for both BT (r > 0.94, P 0.80, P < 0.001). Surgery produced temporary minor inflammation and scrotal hematoma in two animals post-surgery. Whilst scar tissue was observed at all surgical sutured sites when bulls were castrated, there was no evidence of testicular adhesion and normal active spermatogenesis was observed in six of the eight implanted testicles. There was no significant correlation of IRI with either DL or RT. We conclude that DLs provided to be a reliable continuous source of data for synchronous measurement of BT and ST.
Jussi Ryynanen - One of the best experts on this subject based on the ideXlab platform.
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tri phasing modulation for efficient and wideband Radio Transmitters
IEEE Transactions on Circuits and Systems I-regular Papers, 2018Co-Authors: Jerry Lemberg, Mikko Martelius, Marko Kosunen, Enrico Roverato, Kari Stadius, Lauri Anttila, Mikko Valkama, Jussi RyynanenAbstract:In this paper, we show that amplitude transitions that are inherent to the multilevel outphasing Radio transmitter architecture distort the transmitted signal due to time-domain discontinuities. In order to address this challenge, we propose a new transmitter architecture called tri-phasing which avoids discontinuities in signal waveforms and thus achieves significantly better linearity than multilevel outphasing. The output waveform in tri-phasing can be made continuous by representing the baseband signal with three components. One of the three components is amplified by discrete amplitude steps, whereas the other two are used to compensate the instantaneous shift in the output waveform due to the discrete amplitude step and to provide fine amplitude resolution. An implementation of the tri-phasing transmitter requires three phase modulators and additional digital signal processing. The system-level simulations performed in this paper demonstrate that the ACLR of a multilevel outphasing transmitter with 4 amplitude levels and 10-bit phase resolution is limited to −48 dBc, when simulated with a 100 MHz carrier-aggregated LTE downlink signal at 2.46 GHz carrier frequency. The proposed tri-phasing transmitter achieves −58 dBc ACLR with the same simulation parameters, indicating that continuous amplitude transitions can significantly improve the transmitter linearity.