| 1. |
- Khan, H.R., et al.
(författare)
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A 900 MHz 26.8 dBm differential Class-E CMOS power amplifier in German Microwave Conference Digest of Papers, GeMIC 2010, vol , issue , pp 276-279
- 2010
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Ingår i: German Microwave Conference Digest of Papers, GeMIC 2010. ; , s. 276-279
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Konferensbidrag (refereegranskat)abstract
- A 900 MHz differential Class-E amplifier with finite dc inductance has been designed in CMOS. The large inductance of RF choke has been replaced with a finite inductance that provides the required inductive reactance of the class E amplifier. Resonance circuit is realized without series inductor by novel use of lattice LC balun. The amplifier delivers 26.8 dBm power to a 50 O load from a 2.2 V supply. A maximum Power Added Efficiency (PAE) of 43% is achieved.
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| 2. |
- Ahuja, Rajeev, et al.
(författare)
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Optical properties of 4H-SiC
- 2002
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:4, s. 2099-2103
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Tidskriftsartikel (refereegranskat)abstract
- The optical band gap energy and the dielectric functions of n-type 4H-SiC have been investigated experimentally by transmission spectroscopy and spectroscopic ellipsometry and theoretically by an ab initio full-potential linear muffin-tin-orbital method. We present the real and imaginary parts of the dielectric functions, resolved into the transverse and longitudinal photon moment a, and we show that the anisotropy is small in 4H-SiC. The measurements and the calculations fall closely together in a wide range of energies.
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| 3. |
- Arshad, Sana, et al.
(författare)
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50-830 MHz noise and distortion canceling CMOS low noise amplifier
- 2018
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Ingår i: Integration. - : Elsevier. - 0167-9260 .- 1872-7522. ; 60, s. 63-73
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a modified resistive shunt feedback topology is proposed that performs noise cancelation and serves as an opposite polarity non-linearity generator to cancel the distortion produced by the main stage. The proposed topology has a bandwidth similar to a resistive shunt feedback LNA, but with a superior noise figure (NF) and linearity. The proposed wideband LNA is fabricated in 130 nm CMOS technology and occupies an area of 0.5 mm(2). Measured results depict 3-dB bandwidth from 50 to 830 MHz. The measured gain and NF at 420 MHz are 17 dB and 2.2 dB, respectively. The high value of the 1/f noise is one of the key problems in low frequency CMOS designs. The proposed topology also addresses this challenge and a low NF is attained at low frequencies. Measured 811 and S22 are better than -8.9 dB and -8.5 dB, respectively within the 0.05-1 GHz band. The 1-dB compression point is -11.5 dBm at 700 MHz, while the IIP3 is -6.3 dBm. The forward core consumes 14 mW from a 1.8 V supply. This LNA is suitable for VHF and UHF SDR communication receivers.
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| 4. |
- Arshad, Sana, et al.
(författare)
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Highly Linear Inductively Degenerated 0.13 mu m CMOS LNA using FDC Technique
- 2014
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Ingår i: 2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS). - : IEEE. - 9781479952304 ; , s. 225-228
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Konferensbidrag (refereegranskat)abstract
- In this paper, a highly linear, inductively degenerated, common source narrowband LNA is presented. An extremely simple feed-forward distortion circuit (FDC) which consists of an appropriately sized ac-coupled diode connected NMOS is proposed. This circuit generates distortion components at output, when added at the input node as a feed forward element (M-6). These distortion components partially cancel the 3rd order nonlinearity of the cascode pair (M-2 and M-3), thus improving the overall linearity of LNA. The prototype is manufactured in standard 0.13 mu m CMOS process from IBM. Simulation and partial measurement results show the S11 and S22 to be -19.27dB and -7.14dB respectively at 2.45GHz. The simulation results of the LNA demonstrate a power gain of 18.5dB, NF of 4.38dB, input referred 1dBCP of -11.76dBm and IIP3 of +0.7dBm consuming 27.7mA from 1.0V power supply. The proposed LNA achieves the best input referred IIP3 reported in recent literature using 0.13 mu m CMOS in 2.4GHz frequency band.
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| 5. |
- Asghar, M., et al.
(författare)
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Characterization of deep level defects in sublimation grown p-type 6H-SiC epilayers by deep level transient spectroscopy
- 2012
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Ingår i: Physica B: Condensed Matter. - : Elsevier. - 0921-4526.
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Konferensbidrag (refereegranskat)abstract
- In this study deep level transient spectroscopy has been performed on boron-nitrogen co-doped 6H-SiC epilayers exhibiting p-type conductivity with free carrier concentration (N-A-N-D)similar to 3 x 10(17) cm(-3). We observed a hole H-1 majority carrier and an electron E-1 minority carrier traps in the device having activation energies E-nu + 0.24 eV, E-c -0.41 eV, respectively. The capture cross-section and trap concentration of H-1 and E-1 levels were found to be (5 x 10(-19) cm(2), 2 x 10(15) cm(-3)) and (1.6 x 10(-16) cm(2), 3 x 10(15) cm(-3)), respectively. Owing to the background involvement of aluminum in growth reactor and comparison of the obtained data with the literature, the H-1 defect was identified as aluminum acceptor. A reasonable justification has been given to correlate the E-1 defect to a nitrogen donor.
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| 6. |
- Asghar, M., et al.
(författare)
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Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy
- 2007
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:7
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Tidskriftsartikel (refereegranskat)abstract
- Characterization of dominant electron trap in as-grown SiC epilayers has been carried out using deep level transient spectroscopy. Two electron traps E1 and Z1 at Ec-0.21 and Ec-0.61 are observed, respectively, Z1 being the dominant level. Line shape fitting, capture cross section, and insensitivity with doping concentration have revealed interesting features of Z1 center. Spatial distribution discloses that the level is generated in the vicinity of epilayers/substrate interface and the rest of the overgrown layers is defect-free. Owing to the Si-rich growth conditions, the depth profile of Z1 relates it to carbon vacancy. The alpha particle irradiation transforms Z1 level into Z 1/Z2 center involving silicon and carbon vacancies. Isochronal annealing study further strengthens the proposed origin of the debated level. © 2007 American Institute of Physics.
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| 7. |
- Asghar, M., et al.
(författare)
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Study of deep level defects in doped and semi-insulating n-6H-SiC epilayers grown by sublimation method
- 2012
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Ingår i: Physica B: Condensed Matter. - : Elsevier. - 0921-4526.
-
Konferensbidrag (refereegranskat)abstract
- Deep level transient spectroscopy (DLTS) is employed to study deep level defects in n-6H-SiC (silicon carbide) epilayers grown by the sublimation method. To study the deep level defects in n-6H-SiC, we used as-grown, nitrogen doped and nitrogen-boron co-doped samples represented as ELS-1, ELS-11 and ELS-131 having net (N-D-N-A) similar to 2.0 x 10(12) cm(-3), 2 x 10(16) cm(-3) and 9 x 10(15) cm(3), respectively. The DLTS measurements performed on ELS-1 and ELS-11 samples revealed three electron trap defects (A, B and C) having activation energies E-c - 0.39 eV, E-c - 0.67 eV and E-c - 0.91 eV, respectively. While DLTS spectra due to sample ELS-131 displayed only A level. This observation indicates that levels B and C in ELS-131 are compensated by boron and/or nitrogen-boron complex. A comparison with the published data revealed A, B and C to be E-1/E-2, Z(1)/Z(2) and R levels, respectively.
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| 8. |
- Ashraf, H., et al.
(författare)
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Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy
- 2010
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 108:10
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Tidskriftsartikel (refereegranskat)abstract
- Electric field-enhanced emission of electrons from a deep level defect in GaN grown by hydride vapor phase epitaxy has been studied. Using the field dependent mode of conventional deep level transient spectroscopy (DLTS), several frequency scans were performed keeping applied electric field (12.8-31.4 MV/m) and sample temperature (300-360 K) constant. Arrhenius plots of the resultant data yielded an activation energy of the electron trap E ranging from E-c -0.48 +/- 0.02 eV to E-c-0.35 +/- 0.02 eV, respectively. The extrapolation of the as-measured field dependent data (activation energy) revealed the zero-field emission energy (pure thermal activation energy) of the trap to be 0.55 +/- 0.02 eV. Various theoretical models were applied to justify the field-enhanced emission of the carriers from the trap. Eventually it was found that the Poole-Frenkel model associated with a square well potential of radius r=4.8 nm was consistent with the experimental data, and, as a result, the trap is attributed to a charged impurity. Earlier, qualitative measurements like current-voltage (I-V) and capacitance-voltage (C-V) measurements were performed, and screening parameters of the device were extracted to ascertain the reliability of DLTS data.
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| 9. |
- Azam, Sher, 1971-, et al.
(författare)
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A New Load Pull TCAD Simulation Technique for Class D, E & FSwitching Characteristics of Transistors
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We have further developed a computational load pull simulation technique inTCAD. It can be used to study the Class-D, E & F switching response of the transistors. Westudied our enhanced version of previously fabricated and tested SiC transistor. Thesimulated Gain (dB), Power density (W/mm), switching loss (W/mm) and power addedefficiency (PAE %) at 500 MHz were studied using this technique. A PAE of 84 % at500MHz with 26 dB Power gain and power density of 2.75 W/mm is achieved. Thistechnique allows the prediction of switching response of the device before undertaking anexpensive and time-consuming device fabrication. The beauty of this technique is that, weneed no matching and other lumped element networks to study the large signal switchingbehavior of RF and microwave transistors.
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| 10. |
- Azam, Sher, 1971-, et al.
(författare)
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Broadband Power Amplifier performance of SiC MESFET and CostEffective SiGaN HEMT
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes the broadband power amplifier performance of two differentwide band gap technology transistors at 0.7 to 1.8 GHz using cost effective NitronexGaN HEMT on Silicon (Si) and Cree Silicon Carbide MESFET. The measured resultsfor GaN amplifier are; maximum output power at Vd = 28 V is 42.5 dBm (~18 W), amaximum PAE of 39 % and a maximum gain of 19.5 dB is obtained. The measuredmaximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W),with a PAE of 32 % and a power gain above 10 dB. At a drain bias of Vd = 66 V at700 MHz for SiC MESFET amplifier the Pmax was 42.2 dBm (~16.6 W) with a PAE of34.4 %.
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