This article describes the work developed during the academic year 2015/2016 within the scope of ... more This article describes the work developed during the academic year 2015/2016 within the scope of the curricular unit of Project of the Undergraduate in Electrical and Computer Engineering of the Superior School of Technology and Management (ESTG). Ideas and objectives are presented, as well as the used methodologies and the prototypes developed in order to make the interaction between children and adapted toys easier and fun. In close touch with the campaign "Mil Brinquedos Mil Sorrisos" some strategies were defined together to improve this interaction through innovation and improvement of devices already developed. In a first approach, a research on existing alternative interfaces for adapted toys was done. The necessary requirements for each system, their operation method, energy consumption and price were also addressed. Two interaction systems were developed: a wired and a wireless system. The latter system involves two elements: an emitter and a receiver. Associated w...
This article proposes a Radio Frequency Identification (RFID) system for location proposes based ... more This article proposes a Radio Frequency Identification (RFID) system for location proposes based on the use of the nonlinear distortion, specially the 3rd order Intermodulation Distortion (IMD). This new configuration allows the use of the same RF path in transmission and reception of the same signal, improving the correct measurement of the time of travel. In addition the TAG configuration is less complex and need less components. This configuration offers the possibility to develop a semi-passive TAG (or even an almost passive one).
2010 IEEE MTT-S International Microwave Symposium, 2010
This paper presents an analysis of long term-memory effects on power measurements with diode powe... more This paper presents an analysis of long term-memory effects on power measurements with diode power probes. We show that a power probe calibrated with a single-tone sinusoidal excitation can provide erroneous values when used with modulated signals. This fact is ascribed to the low-frequency response imposed by the power probe baseband circuit. This hypothesis is first theoretically demonstrated by use of a Volterra series, and then validated by simulations and measurements using a diode power probe.
IEEE Transactions on Microwave Theory and Techniques, 2011
A new view of diode power probes is presented is this paper. It is shown analytically, by simulat... more A new view of diode power probes is presented is this paper. It is shown analytically, by simulations, and with measurements, that calibration procedures for diode power probes should be rethought when measuring new wireless standard types of signals. In this respect, an improved analysis of long term-memory effects and the behavior of power probes when in the presence of wideband and high peak-to-averagepower ratio signals is analyzed and studied. We show that a power probe calibrated with a single-tone sinusoidal excitation can provide erroneous values when used with modulated signals. This is ascribed to the lowfrequency response imposed by the power probe baseband circuit. This hypothesis is first theoretically demonstrated by use of a Volterra series and then validated by simulations and measurements using a diode power probe. A similar approach is used for high PAPR signals when using multisines as the excitation signal.
Advanced Microwave and Millimeter Wave Technologies: Semiconductor Devices, Circuits and Systems ... more Advanced Microwave and Millimeter Wave Technologies: Semiconductor Devices, Circuits and Systems 496 some considerations about the implementation of adaptable wideband architectures and multi-standard operation. In the following section several interference problems as blocking and PAPR problems will be analyzed. Furthermore, a few techniques of PAPR reduction are overviewed to receiver application. After that, two possible application fields of these concepts are addressed, wherein two projects are shown regarding the radio-frequency identification (RFID) and software-defined radio (SDR) systems. Finally, the concluding remarks are drawn. 2. Review of Receiver Front-Ends Architectures This chapter is intended to make a review of the main receiver's architectures known, show the main applications and study their main advantages and limitations (Besser & Gilmore, 2003), (Razavi, 1997), (Razavi, 1998). 2.1 Super-Heterodyne Receiver The most common configuration used in RF receivers is the well known super-heterodyne architecture (Fig. 1). This configuration is based in two down-conversion stages, i.e., the RF received signal is first demodulated to an intermediate frequency (IF) and then converted to baseband signal. The received signal (Fig. 2a) is first filtered by a pre-selection filter and (after amplified by the low-noise amplifier, (LNA)) passes through another filter to reduce the image frequency effects before the first translation from RF to IF (Fig. 2b e 2c). After this stage, the signal is again filtered and demodulated to baseband (Fig. 2d), where it is converted to the digital domain where it can be processed. In this stage some architectures make an I/Q modulation in order to achieve better amplitude/phase information from the signal received. Receiver Front-End Architectures-Analysis and Evaluation 499 2.3 Low-IF Receiver A similar configuration to the previous one is the low-IF receiver (Adiseno et al., 2002), Fig. 5, in which the RF signal is mixed down to a nonzero low or moderate IF (few hundred kHz to several MHz) instead of going directly to DC, using quadrature RF down-conversion. This solution tries to combine the advantages from the zero-IF receiver and the superheterodyne receiver. Like zero-IF receiver, the received signal (Fig. 6a) passes through a channel-selection filter at RF and is amplified by a LNA (Fig 6b). After this similar step, the signal is down converted to a low IF, instead of zero IF (Fig. 6c), and used an image suppression block in order to cancel the negative effects from frequency image. Finally, an ADC converts the signal to digital domain, allowing the use of digital signal processing algorithms. In some low-IF architectures the image suppression block is transferred to the digital domain.
This article describes the work developed during the academic year 2015/2016 within the scope of ... more This article describes the work developed during the academic year 2015/2016 within the scope of the curricular unit of Project of the Undergraduate in Electrical and Computer Engineering of the Superior School of Technology and Management (ESTG). Ideas and objectives are presented, as well as the used methodologies and the prototypes developed in order to make the interaction between children and adapted toys easier and fun. In close touch with the campaign "Mil Brinquedos Mil Sorrisos" some strategies were defined together to improve this interaction through innovation and improvement of devices already developed. In a first approach, a research on existing alternative interfaces for adapted toys was done. The necessary requirements for each system, their operation method, energy consumption and price were also addressed. Two interaction systems were developed: a wired and a wireless system. The latter system involves two elements: an emitter and a receiver. Associated w...
This article proposes a Radio Frequency Identification (RFID) system for location proposes based ... more This article proposes a Radio Frequency Identification (RFID) system for location proposes based on the use of the nonlinear distortion, specially the 3rd order Intermodulation Distortion (IMD). This new configuration allows the use of the same RF path in transmission and reception of the same signal, improving the correct measurement of the time of travel. In addition the TAG configuration is less complex and need less components. This configuration offers the possibility to develop a semi-passive TAG (or even an almost passive one).
2010 IEEE MTT-S International Microwave Symposium, 2010
This paper presents an analysis of long term-memory effects on power measurements with diode powe... more This paper presents an analysis of long term-memory effects on power measurements with diode power probes. We show that a power probe calibrated with a single-tone sinusoidal excitation can provide erroneous values when used with modulated signals. This fact is ascribed to the low-frequency response imposed by the power probe baseband circuit. This hypothesis is first theoretically demonstrated by use of a Volterra series, and then validated by simulations and measurements using a diode power probe.
IEEE Transactions on Microwave Theory and Techniques, 2011
A new view of diode power probes is presented is this paper. It is shown analytically, by simulat... more A new view of diode power probes is presented is this paper. It is shown analytically, by simulations, and with measurements, that calibration procedures for diode power probes should be rethought when measuring new wireless standard types of signals. In this respect, an improved analysis of long term-memory effects and the behavior of power probes when in the presence of wideband and high peak-to-averagepower ratio signals is analyzed and studied. We show that a power probe calibrated with a single-tone sinusoidal excitation can provide erroneous values when used with modulated signals. This is ascribed to the lowfrequency response imposed by the power probe baseband circuit. This hypothesis is first theoretically demonstrated by use of a Volterra series and then validated by simulations and measurements using a diode power probe. A similar approach is used for high PAPR signals when using multisines as the excitation signal.
Advanced Microwave and Millimeter Wave Technologies: Semiconductor Devices, Circuits and Systems ... more Advanced Microwave and Millimeter Wave Technologies: Semiconductor Devices, Circuits and Systems 496 some considerations about the implementation of adaptable wideband architectures and multi-standard operation. In the following section several interference problems as blocking and PAPR problems will be analyzed. Furthermore, a few techniques of PAPR reduction are overviewed to receiver application. After that, two possible application fields of these concepts are addressed, wherein two projects are shown regarding the radio-frequency identification (RFID) and software-defined radio (SDR) systems. Finally, the concluding remarks are drawn. 2. Review of Receiver Front-Ends Architectures This chapter is intended to make a review of the main receiver's architectures known, show the main applications and study their main advantages and limitations (Besser & Gilmore, 2003), (Razavi, 1997), (Razavi, 1998). 2.1 Super-Heterodyne Receiver The most common configuration used in RF receivers is the well known super-heterodyne architecture (Fig. 1). This configuration is based in two down-conversion stages, i.e., the RF received signal is first demodulated to an intermediate frequency (IF) and then converted to baseband signal. The received signal (Fig. 2a) is first filtered by a pre-selection filter and (after amplified by the low-noise amplifier, (LNA)) passes through another filter to reduce the image frequency effects before the first translation from RF to IF (Fig. 2b e 2c). After this stage, the signal is again filtered and demodulated to baseband (Fig. 2d), where it is converted to the digital domain where it can be processed. In this stage some architectures make an I/Q modulation in order to achieve better amplitude/phase information from the signal received. Receiver Front-End Architectures-Analysis and Evaluation 499 2.3 Low-IF Receiver A similar configuration to the previous one is the low-IF receiver (Adiseno et al., 2002), Fig. 5, in which the RF signal is mixed down to a nonzero low or moderate IF (few hundred kHz to several MHz) instead of going directly to DC, using quadrature RF down-conversion. This solution tries to combine the advantages from the zero-IF receiver and the superheterodyne receiver. Like zero-IF receiver, the received signal (Fig. 6a) passes through a channel-selection filter at RF and is amplified by a LNA (Fig 6b). After this similar step, the signal is down converted to a low IF, instead of zero IF (Fig. 6c), and used an image suppression block in order to cancel the negative effects from frequency image. Finally, an ADC converts the signal to digital domain, allowing the use of digital signal processing algorithms. In some low-IF architectures the image suppression block is transferred to the digital domain.
Uploads
Papers by Hugo Gomes