@inproceedings{RudolphLenkDoerneretal., author = {Rudolph, Matthias and Lenk, Friedrich and D{\"o}rner, Ralf and Heymann, Peter}, title = {Influence of 2 GHz Harmonic Load-Pull on HBT and MESFET Output Power and Efficiency}, series = {1999 IEEE MTT-S International Microwave Symposium digest, June 13 - 19, 1999, Anaheim Convention Center, Anaheim, California}, booktitle = {1999 IEEE MTT-S International Microwave Symposium digest, June 13 - 19, 1999, Anaheim Convention Center, Anaheim, California}, publisher = {Piscataway, NJ}, address = {IEEE}, isbn = {0-7803-5135-5}, pages = {741 -- 744}, language = {en} } @inproceedings{RudolphDoernerHeymannetal., author = {Rudolph, Matthias and D{\"o}rner, Ralf and Heymann, Peter and Lenk, Friedrich}, title = {Modeling of Low-Frequency Noise in GaInP/GaAs Hetero-Bipolar-Transistors}, series = {2001 IEEE MTT-S International Microwave Symposium digest, May 20 - 25, 2001, Phoenix Civic Plaza, Phoenix, AZ, 1967 - 1970, Vol.3}, booktitle = {2001 IEEE MTT-S International Microwave Symposium digest, May 20 - 25, 2001, Phoenix Civic Plaza, Phoenix, AZ, 1967 - 1970, Vol.3}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-6538-0}, pages = {1967 -- 1970}, language = {en} } @inproceedings{LenkRudolph, author = {Lenk, Friedrich and Rudolph, Matthias}, title = {New Extraction Algorithm for GaAs-HBTs With Low Intrinsic Base Resistance}, series = {IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, Vol. 2}, booktitle = {IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, Vol. 2}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7239-5}, pages = {725 -- 728}, language = {en} } @inproceedings{RudolphLenkDoerneretal., author = {Rudolph, Matthias and Lenk, Friedrich and D{\"o}rner, Ralf and Heymann, Peter}, title = {Towards a Unified Method to Implement Transit-Time Effects in Pi-Topology HBT CompactModels}, series = {IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, Vol. 2}, booktitle = {IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, Vol. 2}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7239-5}, pages = {997 -- 1000}, language = {en} } @misc{RudolphLenkLlopisetal., author = {Rudolph, Matthias and Lenk, Friedrich and Llopis, O. and Heinrich, Wolfgang}, title = {On the Simulation of Low-Frequency Noise Upconversion in InGaP/GaAs HBTs}, series = {IEEE transactions on microwave theory and techniques}, volume = {54}, journal = {IEEE transactions on microwave theory and techniques}, number = {7}, issn = {0018-9480}, pages = {2954 -- 2961}, language = {en} } @misc{LenkDoernerRumiantsev, author = {Lenk, Friedrich and D{\"o}rner, Ralf and Rumiantsev, Andrej}, title = {Sensitivity Analysis of S-Parameter Measurements Due to Calibration Standards Uncertainty}, series = {IEEE Transactions on Microwave Theory and Techniques}, volume = {61}, journal = {IEEE Transactions on Microwave Theory and Techniques}, number = {10}, issn = {0018-9480}, doi = {10.1109/TMTT.2013.2279774}, pages = {3800 -- 3807}, language = {en} } @misc{LenkSchottHilsenbecketal., author = {Lenk, Friedrich and Schott, Matthias and Hilsenbeck, Jochen and Heinrich, Wolfgang}, title = {A new design approach for low phase-noise reflection-type MMIC oscillators}, series = {IEEE transactions on microwave theory and techniques}, volume = {52}, journal = {IEEE transactions on microwave theory and techniques}, number = {12}, issn = {0018-9480}, doi = {10.1109/TMTT.2004.837319}, pages = {2725 -- 2731}, abstract = {In this paper, optimization of the loaded quality factor QL for reflection-type heterojunction bipolar transistor (HBT) oscillators is investigated. The main result is an optimum relation between the S-parameter phases at the three transistor ports. A new design strategy for this type of oscillator is proposed. The analysis is verified by comparing several Ka-band monolithic-microwave integrated-circuit oscillators in GaAs HBT technology with different resonators. The measured loaded QL values correspond to the measured phase noise of the circuits. At an oscillation frequency of 33 GHz, an excellent phase noise of -87 dBc/Hz at 100-kHz offset frequency is achieved over the whole tuning range.}, language = {en} } @misc{SoniaRichterBrunneretal., author = {Sonia, G. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Mai, M. and Lenk, Friedrich and Bundesmann, J. and Pensl, G. and Schmidt, J. and Zeimer, U. and Wang, L. and Baskar, K. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {2 MeV ion irradiation effects on AlGaN/GaN HFET devices}, series = {Solid-State Electronics}, volume = {52}, journal = {Solid-State Electronics}, number = {7}, issn = {0038-1101}, pages = {1011 -- 1017}, abstract = {AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with 2 MeV protons, carbon, oxygen, iron and krypton ions with fluences ranging from 1 × 109 cm-2 to 1 × 1013 cm-2. DC, pulsed I-V characteristics, loadpull and S-parameters of the AlGaN HFET devices were measured before and after irradiation. In parallel, a thick GaN reference layer was also irradiated with the same ions and was characterized by X-ray diffraction, photoluminescence, Hall measurements before and after irradiation. Small changes in the device performance were observed after irradiation with carbon and oxygen at a fluence of 5 × 1010 cm-2. Remarkable changes in device characteristics were seen at a fluence of 1 × 1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly, remarkable changes were also observed in the GaN layer for irradiations with fluence of 1 × 1012 cm-2. The results found on devices and on the GaN layer were compared and correlated.}, language = {en} } @misc{GnanapragasamRichterBrunneretal., author = {Gnanapragasam, S. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Mai, M. and Lenk, Friedrich and Opitz-Coutureau, J. and Pensl, G. and Schmidt, J. and Zeimer, U. and Wang, L. and Krishnan, B. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {Irradiation effects on AlGaN HFET devices and GaN layers}, series = {Journal of Materials Science: Materials in Electronics}, volume = {19}, journal = {Journal of Materials Science: Materials in Electronics}, number = {1}, issn = {1573-482X}, doi = {10.1007/s10854-008-9589-1}, pages = {64 -- 67}, abstract = {AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with protons as well as carbon, oxygen, iron and krypton ions of high (68 and 120 MeV) and low (2 MeV) energy with fluences in the range from 1x107 to 1x1013 cm-2. High energy irradiation with protons, carbon and oxygen produced no degradation in devices while krypton irradiation at the fluence of 1x1010 cm-2 resulted in a small reduction of 2\% in the transconductance. Similarly, for GaN samples irradiated with protons, carbon and oxygen at high energy no changes were seen by XRD, PL and Hall effect, while changes in lattice constant and a reduction in PL intensity were observed after irradiation with high energy krypton. Low energy irradiation with carbon and oxygen at a fluence of 5x1010 cm-2 results in small change in the device performance while remarkable changes in device characteristics are seen at a fluence of 1x1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly changes are also observed by XRD, PL and Hall effect for the thick GaN layer irradiated at the fluence of 1x1012 cm-2. The device results and GaN layer properties are strongly correlated.}, language = {en} } @incollection{Lenk, author = {Lenk, Friedrich}, title = {Kapitel "Modulation" und "Multiplex"}, series = {Taschenbuch der Nachrichtentechnik}, booktitle = {Taschenbuch der Nachrichtentechnik}, editor = {Frohberg, Wolfgang}, publisher = {Fachbuchverlag Leipzig im Carl Hanser Verlag}, address = {M{\"u}nchen}, isbn = {3-446-41602-1}, pages = {108 -- 130}, language = {de} } @misc{SoniaRichterBrunneretal., author = {Sonia, G. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Lenk, Friedrich and Opitz-Coutureau, J. and Mai, M. and Schmidt, J. and Zeimer, U. and Wang, L. and Baskar, K. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {High energy irradiation effects on AlGaN/GaN HFET devices}, series = {Semiconductor Science and Technology}, volume = {22}, journal = {Semiconductor Science and Technology}, number = {11}, issn = {0268-1242}, doi = {10.1088/0268-1242/22/11/007}, pages = {1220 -- 1224}, abstract = {The effect of proton, carbon, oxygen and krypton irradiation on AlGaN HFET devices has been studied. Irradiation was performed at 68 and 120 MeV with fluences in the range from 1 × 10^7 to 1 × 10^13 cm2 . Before and after irradiation, dc and pulsed I - V characteristics, loadpull and S -parameters of the AlGaN HFET devices were measured. A thick GaN reference layer was characterized by x-ray diffraction, photoluminescence and Hall measurements before and after irradiation. Proton, carbon and oxygen irradiation show no degradation in devices while krypton irradiation shows a small change at a fluence of 1 × 10 10 cm2 in the device characteristics. The device results are correlated with the thick GaN results.}, language = {en} } @inproceedings{RumiantsevDoernerLenk, author = {Rumiantsev, Andrej and D{\"o}rner, Ralf and Lenk, Friedrich}, title = {Impact of in-situ TRL reference impedance determination on parameter extraction}, series = {Microwave Conference (EuMC), 2012 42nd European, Amsterdam, Netherlands, 29 October - 1 November 2012}, booktitle = {Microwave Conference (EuMC), 2012 42nd European, Amsterdam, Netherlands, 29 October - 1 November 2012}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-2215-7}, pages = {593 -- 596}, abstract = {This paper investigates the impact of possible parameter extraction errors caused by inaccurate definition of the calibration reference impedance of in-situ multiline TRL. Two calibration sets implemented on GaAs and Si/SiGe:C wafer processes were quantitatively analyzed. Obtained results demonstrated that for most practical cases, the desired 5\%-level of confidence of extracted parameters of high-reflective devices can easily be achieved without additional efforts. Thus, implementation of the in-situ TRL into a characterization workflow of high-performance microwave devices can be significantly simplified.}, language = {en} } @inproceedings{BerndtMroskDoerneretal., author = {Berndt, Sebastian and Mrosk, Till and D{\"o}rner, Ralf and Lenk, Friedrich}, title = {Residual errors in coplanar on-chip 1-port calibration caused by standard deviations}, series = {Microwave Measurement Conference (ARFTG), 2013 81st ARFTG, Seattle, Washington, USA, 7 June 2013}, booktitle = {Microwave Measurement Conference (ARFTG), 2013 81st ARFTG, Seattle, Washington, USA, 7 June 2013}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-4981-9}, doi = {10.1109/ARFTG.2013.6579054}, pages = {141 -- 144}, abstract = {The uncertainty calculation for on-wafer 1-port S-Parameter measurements due to the uncertainty of coplanar on-chip calibration standards is presented. Analytical expressions for the sensitivities are used and applied for typical fabrication tolerances of monolithic integrated on-chip structures. The method is verified for OSM calibration by means of simulations with a commercial calibration software as well as by measurements, where test-structures with artificial errors were used. In each case the analytically calculated deviation is compared to a numerical approach and good agreement is found. All results are given for a MMIC process on GaAs, but can be adopted for other technologies.}, language = {en} } @inproceedings{HilsenbeckBrunnerLenketal., author = {Hilsenbeck, Jochen and Brunner, F. and Lenk, Friedrich and W{\"u}rfl, Joachim}, title = {Fabrication and Electrical Performance of Oscillators in GaAs/GaInP-HBT MMIC Technology up to 40 GHz}, series = {29th International Symposium on Compound Semiconductors (ISCS), Lausanne/Switzerland, 2002}, booktitle = {29th International Symposium on Compound Semiconductors (ISCS), Lausanne/Switzerland, 2002}, publisher = {Institute of Physics Publ.}, address = {Bristol [u.a.]}, isbn = {0-7503-0942-3}, pages = {239 -- 242}, language = {en} } @inproceedings{SchmueckleLenkHutteretal., author = {Schm{\"u}ckle, Franz-Josef and Lenk, Friedrich and Hutter, M. and Klein, M. and Oppermann, H. and Engelmann, G. and Topper, M. and Riepe, K. and Heinrich, Wolfgang}, title = {W-band flip-chip VCO in thin-film environment}, series = {2005 IEEE MTT-S International Microwave Symposium, June 12 - 17, 2005, Long Beach, CA}, booktitle = {2005 IEEE MTT-S International Microwave Symposium, June 12 - 17, 2005, Long Beach, CA}, publisher = {IEEE Operations Center}, address = {Piscataway, NJ}, isbn = {0-7803-8845-3}, doi = {10.1109/MWSYM.2005.1516837}, abstract = {A flip-chip packaging approach for W-band GaAs chips is presented using thin-film structures on silicon as carrier substrate. Reliability investigations indicate that, depending on bump size, the CTE mismatch is not critical and an underfiller does not provide distinctive benefits. A 77 GHz VCO GaAs-HBT MMIC is flip-chip-mounted to demonstrate validity of the packaging scheme.}, language = {en} } @inproceedings{SchottLenkMelianietal., author = {Schott, Matthias and Lenk, Friedrich and Meliani, Chafik and Heinrich, Wolfgang}, title = {Low phase noise X-band push-push oscillator with frequency divider}, series = {2005 IEEE MTT-S International Microwave Symposium, June 12 - 17, 2005, Long Beach, CA}, booktitle = {2005 IEEE MTT-S International Microwave Symposium, June 12 - 17, 2005, Long Beach, CA}, publisher = {IEEE Operations Center}, address = {Piscataway, NJ}, isbn = {0-7803-8845-3}, doi = {10.1109/MWSYM.2005.1516986}, abstract = {A MMIC Colpitts oscillator in push-push configuration with integrated frequency divider using InGaP/GaAs HBTs is presented. The output is taken from the second harmonic port while the fundamental signal is fed to a frequency divider by two thus providing a reference signal at one quarter of the output frequency. The MMIC VCO reaches state-of-the-art phase-noise performance in X-band down to -120dBc/Hz at 1MHz offset frequency at high output power and a tuning range of 4\%.}, language = {en} } @inproceedings{LenkSchottHilsenbecketal., author = {Lenk, Friedrich and Schott, Matthias and Hilsenbeck, Jochen and Heinrich, Wolfgang}, title = {Optimizing MMIC reflection-type oscillators}, series = {2004 IEEE MTT-S International Microwave Symposium digest, June 6 - 11, 2004, Fort Worth Convention Center, Fort Worth, Texas, vol. 3}, booktitle = {2004 IEEE MTT-S International Microwave Symposium digest, June 6 - 11, 2004, Fort Worth Convention Center, Fort Worth, Texas, vol. 3}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-8331-1}, doi = {10.1109/MWSYM.2004.1338816}, pages = {1341 -- 1344}, abstract = {In this paper, optimization of the loaded quality factor QL for reflection-type HBT oscillator is investigated. Main result is an optimum relation between the S parameter phases at the three transistor ports. To support this finding, a 35.5 GHz MMIC VCO phase noise better than -85 dBc/Hz at 100 kHz offset frequency is demonstrated.}, language = {en} } @inproceedings{LenkDoerner, author = {Lenk, Friedrich and D{\"o}rner, Ralf}, title = {A new multiport measurement-method using a two-port network analyzer}, series = {2005 IEEE MTT-S International Microwave Symposium, June 12 - 17, 2005, Long Beach, CA}, booktitle = {2005 IEEE MTT-S International Microwave Symposium, June 12 - 17, 2005, Long Beach, CA}, publisher = {IEEE Operations Center}, address = {Piscataway, NJ}, isbn = {0-7803-8845-3}, doi = {10.1109/MWSYM.2005.1517031}, abstract = {A new method is presented how to characterize multiport devices using a two-port vector network-analyzer (VNA). Up to now, at least one of the port terminations had to be fully known to measure the S-parameters of the device. Our new measurement method overcomes this restriction. All of the device parameters and all of the port terminations are calculated from the device measurements.}, language = {en} } @inproceedings{LenkDoernerKurpasetal., author = {Lenk, Friedrich and D{\"o}rner, Ralf and Kurpas, Paul and Rumiantsev, Andrej}, title = {Measurement uncertainties due to non-ideal calibration standards for unknown thru calibration}, series = {Microwave Measurement Conference (ARFTG), 2013 81st ARFTG}, booktitle = {Microwave Measurement Conference (ARFTG), 2013 81st ARFTG}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-4981-9}, doi = {10.1109/ARFTG.2013.6579057}, pages = {1 -- 4}, language = {en} } @inproceedings{LenkSchottHilsenbecketal., author = {Lenk, Friedrich and Schott, Matthias and Hilsenbeck, Jochen and W{\"u}rfl, Joachim and Heinrich, Wolfgang}, title = {Low phase-noise monolithic GaInP/GaAs-HBT VCO for 77 GHz}, series = {2003 IEEE MTT-S International Microwave Symposium digest, June 8 - 13, 2003, Pennsylvania Convention Center, Philadelphia, Pennsylvania, vol. 2}, booktitle = {2003 IEEE MTT-S International Microwave Symposium digest, June 8 - 13, 2003, Pennsylvania Convention Center, Philadelphia, Pennsylvania, vol. 2}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7695-1}, doi = {10.1109/MWSYM.2003.1212515}, pages = {903 -- 906}, abstract = {Coplanar W-band push-push VCO MMICs using GaInP/GaAs HBTs are presented. One circuit operates at 77 GHz with phase noise of -92 dBc/Hz at 1 MHz offset. To our knowledge this is the first fully monolithic W-band VCO with phase noise better than -90 dBc/Hz. A second version with two varactor diodes yields an almost threefold relative tuning bandwidth.}, language = {en} } @inproceedings{KuhnertLenkHilsenbecketal., author = {Kuhnert, Holger and Lenk, Friedrich and Hilsenbeck, Jochen and W{\"u}rfl, Joachim and Heinrich, Wolfgang}, title = {Low phase-noise GaInP/GaAs-HBT MMIC oscillators up to 36 GHz}, series = {2001 IEEE MTT-S International Microwave Symposium digest, May 20 - 25, 2001, Phoenix Civic Plaza, Phoenix, AZ, vol. 3}, booktitle = {2001 IEEE MTT-S International Microwave Symposium digest, May 20 - 25, 2001, Phoenix Civic Plaza, Phoenix, AZ, vol. 3}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-6538-0}, doi = {10.1109/MWSYM.2001.967198}, pages = {1551 -- 1554}, abstract = {Monolithic coplanar 18 and 36 GHz oscillators with GaInP/GaAs-HBTs and on-chip resonators are presented. Measured phase-noise reaches -93 dBc/Hz and -91 dBc/Hz at 100 kHz offset for 18 and 36 GHz, respectively. These values demonstrate that GaAs-HBT oscillators yield a phase-noise performance comparable to SiGe-HBTs, with the potential for higher frequencies.}, language = {en} } @inproceedings{SchottKuhnertLenketal., author = {Schott, Matthias and Kuhnert, Holger and Lenk, Friedrich and Hilsenbeck, Jochen and W{\"u}rfl, Joachim and Heinrich, Wolfgang}, title = {38 GHz push-push GaAs-HBT MMIC oscillator}, series = {2002 IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, vol. 2}, booktitle = {2002 IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, vol. 2}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7239-5}, doi = {10.1109/MWSYM.2002.1011761}, pages = {839 -- 842}, abstract = {Two differential coplanar MMIC HBT oscillators are presented, a fixed frequency and a VCO version. They provide single-ended output at the second harmonic at 38 GHz as well as differential output at 19 GHz. The oscillators show excellent phase noise performance, the fixed-frequency type reaches -95 dBc/Hz at the fundamental frequency and -89 dBc/Hz at the second harmonic, at 100 kHz offset.}, language = {en} } @inproceedings{LenkDoerner, author = {Lenk, Friedrich and D{\"o}rner, Ralf}, title = {Improved parameter extraction of small-sized FETs for low-power applications}, series = {2000 IEEE MTT-S International Microwave Symposium digest, June 11 - 16, 2000, Hynes Convention Center, Boston, Massachusetts, vol. 3}, booktitle = {2000 IEEE MTT-S International Microwave Symposium digest, June 11 - 16, 2000, Hynes Convention Center, Boston, Massachusetts, vol. 3}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-5687-X}, doi = {10.1109/MWSYM.2000.862233}, pages = {1389 -- 1392}, abstract = {In low-power applications FETs with small gate width are required. For such devices common extraction methods fail. In particular, extracting source inductance and drain pad capacitance using "cold"-FET measurements is no longer possible. We present an improved method that allows reliable extraction of extrinsic elements for small-sized FETs.}, language = {en} } @inproceedings{HilsenbeckLenkLossyetal., author = {Hilsenbeck, Jochen and Lenk, Friedrich and Lossy, Richard and W{\"u}rfl, Joachim and Kohler, K. and Obloh, H.}, title = {DC and microwave properties of 0.5 um AlGaN/GaN high electron mobility transistors fabricated on 2-inch process line}, series = {IEEE International Symposium on Compound Semiconductors, held in Monterey, California, 2 - 5 October 2000}, booktitle = {IEEE International Symposium on Compound Semiconductors, held in Monterey, California, 2 - 5 October 2000}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-6258-6}, doi = {10.1109/ISCS.2000.947181}, pages = {351 -- 356}, abstract = {DC and RF characteristics of AlGaN/GaN HEMTs processed by 2-inch stepper lithography are presented. The devices, grown by MOVPE on 2" sapphire wafers consist of: GaN buffer, Al0.25Ga0.75 N spacer, doped Al0.25Ga0.75N supply layer, Al0.25Ga0.75N barrier, GaN cap. Refractory source and gate contacts along with mesa isolation and air bridge technology are applied. Typical values for maximum saturation current, transconductance and pinch-off voltage are: 616 m/A/mm, 203 mS/mm, -3.5 V with very good homogeneity across 2". The cut off frequencies fT and fmax are 24 and 54 GHz respectively. A standard small signal equivalent circuit model exactly describes DC- and microwave properties}, language = {en} } @inproceedings{MelianiLenkHeinrich, author = {Meliani, Chafik and Lenk, Friedrich and Heinrich, Wolfgang}, title = {24 GHz Low Power VCOs and Analog Frequency Dividers}, series = {IEEE MTT-S International Microwave Symposium digest, 11 - 16 June 2006, San Francisco, CA}, booktitle = {IEEE MTT-S International Microwave Symposium digest, 11 - 16 June 2006, San Francisco, CA}, publisher = {IEEE Operations Center}, address = {Piscataway, NJ}, isbn = {0-7803-9541-7}, doi = {10.1109/MWSYM.2006.249744}, pages = {1801 -- 1804}, abstract = {24 GHz VCOs and frequency dividers with very low power consumption are presented. The circuits are realized as GaAs HBT MMICs. They comprise a VCO with high efficiency >17\% and 12\% tuning range at only 18 mW DC consumption as well as several frequency dividers. In order to minimize power consumption, the latter use the injection-locked frequency-divider (ILFD) concept. Divider ratios of 2 and 4 are realized, power consumption as low as 25 mW for a divider-by-2 is achieved. This demonstrates the capabilities of the analog concept in realizing dividers for mm-wave frequencies at DC consumption levels far below their digital counterparts}, language = {en} } @inproceedings{LenkSchottHeinrich, author = {Lenk, Friedrich and Schott, Matthias and Heinrich, Wolfgang}, title = {Modeling and Measurement of Phase Noise in GaAs HBT Ka-Band Oscillators}, series = {31st European Microwave Conference, 2001, 24 - 26 Sept. 2001}, booktitle = {31st European Microwave Conference, 2001, 24 - 26 Sept. 2001}, publisher = {Microwave Engineering Europe}, address = {London}, doi = {10.1109/EUMA.2001.339168}, pages = {1 -- 4}, abstract = {Accurate oscillator phase-noise simulation is a key problem in MMIC design, which is not solved satisfactory so far and needs further investigation. In this paper, a Ka-band MMIC oscillator with GaInP/GaAs HBT and on-chip resonator is treated as an example. Measured phase noise reaches -90 dBc/Hz and below at 100 kHz offset. To evaluate phase-noise prediction, the circuit is simulated using different commercial simulation tools and HBT models. Considerable differences in simulation results are observed.}, language = {en} } @inproceedings{LenkDoerner, author = {Lenk, Friedrich and D{\"o}rner, Ralf}, title = {New extraction method for FET extrinsic capacitances using active bias conditions}, series = {IEEE MTT-S International Microwave Symposium digest, June 7 - 12, 1998, Baltimore Convention Center, Baltimore, Maryland}, booktitle = {IEEE MTT-S International Microwave Symposium digest, June 7 - 12, 1998, Baltimore Convention Center, Baltimore, Maryland}, publisher = {IEEE Publication}, address = {Piscataway, NJ}, isbn = {0-7803-4471-5}, doi = {10.1109/MWSYM.1998.689374}, pages = {279 -- 282}, abstract = {A new procedure for extracting the extrinsic capacitances of FETs is presented. It requires measurements only in the active bias regime. The method utilizes the symmetry of the intrinsic FET in the forward and reverse biased operating regime. The extraction is performed analytically and does not require any optimization.}, language = {en} } @inproceedings{HilsenbeckLenkHeinrichetal., author = {Hilsenbeck, Jochen and Lenk, Friedrich and Heinrich, Wolfgang and W{\"u}rfl, Joachim}, title = {Low phase noise MMIC VCOs for Ka-band applications with improved GaInP/GaAs-HBT technology}, series = {Gallium Arsenide Integrated Circuit (GaAs IC) Symposium, 2003, 25th Annual Technical Digest 2003, San Diego, California, November 9 - 12, 2003}, booktitle = {Gallium Arsenide Integrated Circuit (GaAs IC) Symposium, 2003, 25th Annual Technical Digest 2003, San Diego, California, November 9 - 12, 2003}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7833-4}, doi = {10.1109/GAAS.2003.1252399}, pages = {223 -- 226}, abstract = {We report on the technology and performance of fully monolithic coplanar voltage-controlled oscillators (VCOs) with GaInP/GaAs-HBTs as the active devices. With our optimized HBT process, the parasitic base resistance R/sub B/ and extrinsic base-collector capacitance C/sub EX/ are significantly reduced. In this way, the maximum frequency of oscillation F/sub max/ is increased from 100 to 170 GHz. This allows us to realize fundamental 38 GHz-VCOs with very low phase noise. At an oscillation frequency F/sub res/=34.2/spl plusmn/0.2 GHz, the VCO reaches phase noise levels of -87 dBc/Hz @ 100 kHz and -108 dBc/Hz @ 1 MHz offset frequency, respectively. To our knowledge, these phase noise values are the lowest GaAs data for Ka-band applications reported so far.}, language = {en} } @inproceedings{LenkKlockenhoffMaassdorfetal., author = {Lenk, Friedrich and Klockenhoff, Harald and Maaßdorf, Andre and W{\"u}rfl, Joachim and Heinrich, Wolfgang}, title = {A 3.2 W coplanar single-device X-band amplifier with GaAs HBT}, series = {Gallium Arsenide and Other Semiconductor Application Symposium, 2005, EGAAS 2005}, booktitle = {Gallium Arsenide and Other Semiconductor Application Symposium, 2005, EGAAS 2005}, publisher = {Horizon House Publ.}, address = {London}, isbn = {88-902012-0-7}, pages = {49 -- 52}, abstract = {High-power GaInP/GaAs HBTs with high breakdown voltage for X-band applications are presented. To demonstrate the capabilities of these devices, a simple monolithic amplifier is realized. For a single 12-finger device with 2/spl times/70 /spl mu/m/sup 2/ emitter finger size, an output power of 3.2 W at 9 GHz with 47\% PAE is achieved.}, language = {en} } @inproceedings{SchottLenkHeymann, author = {Schott, Matthias and Lenk, Friedrich and Heymann, Peter}, title = {On the load-pull effect in MMIC oscillator measurements}, series = {33rd European Microwave Conference, 7 - 9th October 2003, ICM, Munich, Germany, Vol. 1}, booktitle = {33rd European Microwave Conference, 7 - 9th October 2003, ICM, Munich, Germany, Vol. 1}, publisher = {London}, address = {Korizon House Publ.}, isbn = {1-58053-834-7}, doi = {10.1109/EUMC.2003.1262295}, pages = {367 -- 370}, abstract = {Low phase-noise MMIC oscillators are key components for microwave and nun-wave systems. As a consequence, phase-noise measurements of these circuits have become a subject of growing interest and importance. This paper demonstrates that MMIC oscillator circuits with their relatively low Q factors are prone to specific measurement errors. Caused by a load-pull effect, the measurement system can become part of the oscillator, which yields phase-noise data significantly below reality. Special care has to be taken in order to avoid such phenomena.}, language = {en} } @inproceedings{LenkSchottHilsenbecketal., author = {Lenk, Friedrich and Schott, Matthias and Hilsenbeck, Jochen and Heinrich, Wolfgang}, title = {Low phase-noise GaAs-HBT monolithic W-band oscillator}, series = {34th European Microwave Conference, Tuesday 12th, Wednesday 13th and Thursday 14th October}, booktitle = {34th European Microwave Conference, Tuesday 12th, Wednesday 13th and Thursday 14th October}, publisher = {London}, address = {Horizon House Publ.}, isbn = {1-58053-992-0}, pages = {897 -- 900}, language = {en} } @inproceedings{LenkDoernerRumiantsevetal., author = {Lenk, Friedrich and D{\"o}rner, Ralf and Rumiantsev, Andrej and Rudolph, Matthias}, title = {Calibration Residual Error Propagation Analysis Using Conformal Mapping}, series = {77th ARFTG Microwave Measurement Conference (ARFTG 2011), Baltimore, Maryland, USA, 10 June 2011}, booktitle = {77th ARFTG Microwave Measurement Conference (ARFTG 2011), Baltimore, Maryland, USA, 10 June 2011}, publisher = {Piscataway, NJ}, address = {IEEE}, isbn = {978-1-61284-959-1}, pages = {Paper 2-4}, language = {en} } @misc{KraemerMelianiLenketal., author = {Kraemer, Thorsten and Meliani, Chafik and Lenk, Friedrich and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {Transferred substrate DHBT of ft = 410 GHz and fmax = 480 GHz for traveling wave amplifiers}, series = {Indium Phosphide and Related Materials, 2008, IPRM 2008, 20th International Conference, Versailles, France, 25 - 29 May 2008}, journal = {Indium Phosphide and Related Materials, 2008, IPRM 2008, 20th International Conference, Versailles, France, 25 - 29 May 2008}, isbn = {978-1-4244-2258-6}, doi = {10.1109/ICIPRM.2008.4702999}, pages = {1 -- 3}, abstract = {We report a MMIC process in transferred substrate technology. The transistors of 0.8 times 5 mum2 emitter size feature ft = 410 GHz and fmax = 480 GHz at BVceo = 5.5 V. Traveling wave amplifiers of 12 dB broadband gain up to fc = 70 GHz were realized.}, language = {en} } @misc{KraemerLenkMaassdorfetal., author = {Kraemer, Thorsten and Lenk, Friedrich and Maaßdorf, Andre and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {High Yield Transferred Substrate InP DHBT}, series = {Indium Phosphide \& Related Materials, 2007, IPRM '07, IEEE 19th International Conference, Matsue, Japan, 14 - 18 May 2007}, journal = {Indium Phosphide \& Related Materials, 2007, IPRM '07, IEEE 19th International Conference, Matsue, Japan, 14 - 18 May 2007}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {1-4244-0875-X}, doi = {10.1109/ICIPRM.2007.381210}, pages = {407 -- 408}, abstract = {A transferred substrate InP DHBT of 0.8 mum emitter width was developed. The transistors featured high yield and homogeneous device characteristics over the three inch wafer, with an average of ft = 300 GHz plusmn 3\%SD, fmax = 250 GHz plusmn 5\%SD at a breakdown voltage of BVceo = 6 V.}, language = {en} }