This letter describes a novel three-port absorptive limiter for frequency-selective circuits based on a configuration similar to a conventional 90° hybrid coupler. This circuit uses the switching behavior of common diodes to change between the nonlimiting and absorptive limiting states. Theoretical descriptions and designs are presented along with prototypes based on PIN diodes. Measurements of the limiting performance of the devices at approximately 2 GHz as a function of power demonstrate the viability of the concept.
Gilabert, Pere L.; Montoro, G.; Ruiz, M.; García, J. IEEE microwave and wireless components letters Vol. 26, num. 7, p. 513-515 DOI: 10.1109/LMWC.2016.2574825 Data de publicació: 2016-07-01 Article en revista
This letter presents an adaptive envelope shaping (AES) method to linearize low and medium power amplifiers (PAs) with dynamic supply. This straightforward linearization solution results very useful for small cell or handset transmitters, where reducing power consumption and computational complexity of the digital part is crucial. With the AES method, there is no need of an a priori characterization of the PA to shape the supply voltage signal targeting maximum linearity. Excellent linearization results are obtained when the PA presents good AM-PM linearity, otherwise, additional phase distortion linearization has to be included to meet the ACLR specifications.
A novel Doherty-like power amplifier (DPA) has been fabricated using 15 W, 2.7 GHz, GaN HEMT transistors. The quarter-wave transformer used in the classical DPA topology is replaced by a matching network including a Klopfenstein taper. From a practical prototype realization, this modification has demonstrated that the resulting DPA bandwidth (BW) is increased in comparison with the conventional topology while keeping the efficiency figures. Moreover, this design allows an
easy tuning of the group delay through the output reactance of the taper, resulting in a more straightforward adjustments than other recently-published designs where the quarter-wave transformer is replaced by multi-section transmission lines (hybrid or similar). Experimental results have shown an average efficiency of 47.2% for the HSPA+ modulation centered at 2.25GHz.
Aragones, X.; Mateo, D.; Gonzalez, J.; Vidal, E.; Gómez, D.; Martineau, B.; Altet, J. IEEE microwave and wireless components letters Vol. 25, num. 11, p. 745-747 DOI: 10.1109/LMWC.2015.2479848 Data de publicació: 2015-11 Article en revista
This letter shows how a temperature sensor and a simple DC voltage multimeter can be used as instruments to determine the central frequency and 3 dB bandwidth of a 60 GHz linear power amplifier (PA). Compared to previous works, the DC temperature monitoring now proposed requires a much simpler and convenient measurement set-up. In this example, the temperature sensor is embedded in the same silicon die as the PA. Being placed in empty layout spaces next to it, it is proposed as a built-in test circuit.
Collado, J.; Hueltes, A.; Rocas, E.; Mateu, J.; Booth, J.; O'callaghan, J.; Verdu, J. IEEE microwave and wireless components letters Vol. 24, num. 6, p. 415-417 DOI: 10.1109/LMWC.2014.2313583 Data de publicació: 2014-06-01 Article en revista
This letter describes a novel absorptive limiter for frequency-selective circuits. The proposed circuit allows the design of absorptive limiters based on a bi-state phase shifter, which is appropriate for integration into channelizing devices, such as hybrid-coupled input multiplexers. A preliminary prototype with shunt PIN diodes has been fabricated and measured to demonstrate the viability of the concept.
This letter introduces a novel on-chip measurement technique for the determination of the central frequency and 3 dB bandwidth of a 60 GHz power amplifier (PA) by performing low frequency temperature measurements. The temperature sensor is embedded in the same silicon die as the PA, and placed in empty spaces next to it. Results confirm that temperature sensors can be used as functional built-in testers which serve to reduce testing costs and enhance yield as part of self-healing strategies.
Silveira, D.D.; Gilabert, Pere L.; Dos Santos, A.B.; Gadringer, M.E. IEEE microwave and wireless components letters Vol. 23, num. 8, p. 442-444 DOI: 10.1109/LMWC.2013.2268456 Data de publicació: 2013 Article en revista
This article discusses several different implementations of Volterra series models, and performs a fair comparison between them using measured data and well known figures of merit. Among the implemented models, an approach that uses sub-sampling techniques together with Volterra series in a parallel cascade structure shows an improved performance compared to the other variations of Volterra series models. Based on the results, new trends in RF power amplifier behavioral modeling are suggested.
This article discusses several different implementations of Volterra seriesmodels, and performs a fair comparison between them using measured data and well known figures of merit.
Among the implemented models, an approach that uses sub-sampling techniques together with Volterra series in a parallel cascade structure shows an improved performance compared to the other variations of Volterra seriesmodels.Based on the results, new trends in RF power amplifier behavioral modeling are suggested.
This letter presents a dynamic slow envelope dependent digital predistorter (SED-DPD) capable of compensating for the nonlinear distortion and memory effects that arise in envelope tracking (ET) power amplifiers (PAs) when using a slow version of the signal's envelope to dynamically supply the PA drain voltage. Moreover, a new DPD architecture based on the combination of several basic predistortion cells (BPCs) is presented to allow the FPGA implementation of the proposed SED-DPD. Finally, results showing the necessity and linearization performance of the proposed dynamic SED-DPD are provided.
Capdevila, S.; Jofre, L.; Romeu, J.; Bolomey, J.Ch. IEEE microwave and wireless components letters Vol. 22, num. 8, p. 436-438 DOI: 10.1109/LMWC.2012.2205910 Data de publicació: 2012 Article en revista
In this letter, a measurement technique for a complete
parametric characterization of the input impedance of an RFID
IC is presented. The use of an SPDT switch to modulate the signal
from the network analyzer provides the capability to measure the
RFID IC activation level and its input impedance simultaneously.
This data can then be used to fully predict the dynamic response
and performance of an RFID tag.
This letter presents a novel approach for providing
substrate-integrated waveguide tunable resonators by means of
placing an additional metalized via-hole on the waveguide cavity.
The via-hole contains an open-loop slot on the top metallic wall.
The dimensions, position and orientation of the open-loop slot
defines the tuning range. Fabrication of some designs reveals good
agreement between simulation and measurements. Additionally,
a preliminary prototype which sets the open-loop slot orientation
manually is also presented, achieving a continuous tuning range
Moncunill, F. X.; Palà-Schönwälder, P.; Dehollain, C.; Joehl, N.; Declercq, M. IEEE microwave and wireless components letters Vol. 15, num. 8, p. 499-501 DOI: 10.1109/LMWC.2005.852775 Data de publicació: 2005-08 Article en revista
Garcia-Garcia, J.; Martin, F.; Falcone, F.; Bonache , J.; Gil, I.; Lopetegi, T.; Laso, M.; Sorolla, M.; Marques, R. IEEE microwave and wireless components letters Vol. 40, num. 9, p. 416-418 Data de publicació: 2004-09 Article en revista
Anguera, J.; Font, G.; Puente, C.; Borja, C.; Soler, J. IEEE microwave and wireless components letters Vol. 13, num. 3, p. 123-124 DOI: 10.1109/LMWC.2003.810126 Data de publicació: 2003-03 Article en revista