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Now showing items 33 - 39 of 39

  • [IEEE 2012 80th ARFTG Microwave Measurement Conference - San Diego, CA, USA (2012.11.29-2012.11.30)] 80th ARFTG Microwave Measurement Conference - Pulsed RF calibration for NVNA measurements

    Roblin, Patrick   Ko, Youngseo   Jang, Haedong   Teyssier, Jean Pierre  

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  • [IEEE 2017 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR) - Phoenix, AZ, USA (2017.1.15-2017.1.18)] 2017 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR) - Direct design of Doherty and Chireix PAs using a nonlinear embedding device model

    Roblin, Patrick   Chang, Hsiu-Chen   Liang, Chenyu   Alsulami, Ruwaybih   Martinez-Rodriguez, Francisco   Galaviz Aguilar, Jose Alejandro  

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  • Negative input resistance and real-time active load-pull measurements of a 2.5GHz oscillator using a LSNA

    Hyo Dal Park   Rojas, Roberto   Vanden Bossche, Marc   Strahler, Jeffrey   Young Gi Kim   Cui, Xian   Roblin, Patrick   Seok Joo Doo   Inwon Suh  

    A large-signal measurement-based methodology to design oscillators using the Kurokawa theory is presented in this paper. Measurements of the negative input resistance and device line of a 2.5GHz HEMT oscillator versus frequency and power; and its optimization using real-time active load-pull (RTALP) for the 2nd and 3rd harmonics are performed with a large signal network analyzer (LSNA). As a result; the maximum output power of the oscillator is increased from 31.0mW to 38.8mW. Finally self-oscillation is verified using a load tuner to yield an output power and frequency of oscillation in reasonable agreement with the Kurokawa analysis.
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  • A 5 GHz CMOS Variable Gain Low Noise Amplifier for wireless LAN Applications

    Alam, Shaikh K.   DeGroat, Joanne   Roblin, Patrick  

    This paper describes a 5 GHz fully differential variable gain low noise amplifier (VGLNA) in a 0.18-驴m CMOS process. The LNA provides a 50-驴 input impedance and utilizes a tuned load to provide high selectivity. The VGLNA achieves a maximum small signal gain of 12.34 dB within 1-dB compression point (iCP1dB) of -12.0 dBm and a minimum gain of 6 dB. In the high gain mode (HGM) and low gain mode (LGM); the noise figures (NFs) are 3.89 dB and 4.25 dB; respectively with good input return loss. The LNA's IIP3 in the HGM is - 1.24 dBm. The LNA consumes only 5.79 mA of current from a 1.5-V power supply.
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  • Additive phase noise measurements of AlGaN/GaN HEMTs using a large signal network analyzer and a tunable monochromatic light source

    Mishra, Umesh   Speck, James   Pei, Yi   Poblenz, Christiane   Ringel, Steven   Arehart, Aaron   Malonis, Andrew   Yang, Chieh-Kai   Ko, Youngseo   Roblin, Patrick   Suh, Inwon  

    An additive phase noise measurement system is integrated with a large signal network analyzer (LSNA) and a tunable monochromatic light source. This system is used to measure the additive phase noise characteristics of an unpassivated AlGaN/GaN high electron mobility transistor (HEMT) at 2 GHz under various operating conditions. Illumination with different photon energies; below the AlGaN bandgap; is applied to probe the dependence of the RF additive phase noise on the trap and 2DEG population. Different drain voltages are also used to investigate the bias dependence of the phase noise. From 1 Hz to 10 KHz; an 1/f region is identified in the additive phase noise at 2 GHz; which is indicative of the presence of uniformly distributed traps. Further a decrease in additive phase noise is clearly observed with increasing photon energies below the GaN bandgap. This is due to the decrease of the trap population induced by photon assisted emission of electrons from the trap levels to the conduction band. Further it is found that the additive phase noise at 2 GHz increases at higher drain voltages. Various RF load impedances are also used to further characterize the noise performance of both passivated and unpassivated AlGaN/GaN HEMTs. The larger the drain voltage swing introduced; the more additive phase noise is observed. A degration of additive phase noise is also observed with the unpassivated device compared to the passivated device. Some preliminary results from a physical cyclostationary model are also presented. The observed 1/f noise increase at RF occuring at large bias or in large signal RF operation are attributed to the increase efficiency of the RF upconversion of the trap 1/f occupation fluctuation when the drain resistance increases. This work also demonstrates that the new combined additive phase noise/LSNA testbed developed is a useful tool for characterizing the additive phase noise in transistors/amplifiers under large signal operation.
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  • New Ultra-fast Real-time Active Load-pull Measurements for High Speed RF Power Amplifier Design

    Roblin, Patrick   Doo, Seok Joo   Cui, Xian   Jessen, Gregg H.   Chaillot, Dominique   Strahler, Jeffrey  

    To accelerate the speed of RF power amplifier design; a novel ultra-fast real-time active load-pull measurement based on a large signal network analyzer (LSNA) is presented. Real-time load-pull conventionally uses a single-tone excitation at the transistor's output to achieve a time varying load impedance. However this approach still requires multiple measurements at different power levels to map the Smith Chart and determine the optimal load termination. This paper proposes a modulated two-tone excitation method for mapping the Smith Chart in a single 10 ms LSNA measurement. Experiments for the 1st and 2nd harmonic demonstrate that this ultra-fast real-time active load-pull permits to identify the optimal load impedance in one measurement.
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  • Multi-harmonic broadband measurements using an large signal network analyzer

    Teyssier, Jean Pierre   De Groote, Fabien   Strahler, Jeffrey   Myoung, Sukkeun   Roblin, Patrick   Ko, Youngseo  

    A new testbed was developed with an LSNA to perform multi-harmonic broadband measurements for periodically modulated signals with bandwidth exceeding the IF receiver bandwidth of the LSNA. This testbed is intended for characterizing PAs using periodically modulated (multitone) signals often referred as multisines. Multisine signals can be synthesized to approximate the CCDF and PAPR of digitally modulated signals such as WiMAX and LTE (Long Term Evolution). In the experiment conducted a multisine with 13 tones distributed over 15 MHz was used which provided a PAPR of 6 dB. Using this excitation; the nonlinear response of a 80 W Doherty GaN PA at 2.16 GHz was characterized over a 80 MHz bandwidth. Inband signal distortion and spectral regrowth were recorded in the 63 tones measurement over the 80 MHz measurement bandwidth targeted at both the fundamental and second harmonic. This increased measurement bandwidth enables one to characterize the nonlinear vector response of the PA in its 3rd and 5th order inter-modulation bands at the fundamental frequency. The broadband vector results at the second harmonic obtained in the same measurements provides additional invaluable information for the multi-harmonic optimization of the efficiency of the Doherty PA under test. It is believed that the multi-harmonic broadband vector characterization capabilities provided by the reported testbed should assist with the development and verification of multi-harmonic behavioral models for wideband modulated signals.
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