| 1. |
- Khan, H.R., et al.
(författare)
-
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
-
Ingår i: German Microwave Conference Digest of Papers, GeMIC 2010. ; , s. 276-279
-
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.
|
|
| 2. |
- Arshad, Sana, et al.
(författare)
-
Highly Linear Inductively Degenerated 0.13 mu m CMOS LNA using FDC Technique
- 2014
-
Ingår i: 2014 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS). - : IEEE. - 9781479952304 ; , s. 225-228
-
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.
|
|
| 3. |
- Asghar, M., et al.
(författare)
-
Characterization of deep level defects in sublimation grown p-type 6H-SiC epilayers by deep level transient spectroscopy
- 2012
-
Ingår i: Physica B: Condensed Matter. - : Elsevier. - 0921-4526.
-
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.
|
|
| 4. |
- Asghar, M., et al.
(författare)
-
Study of deep level defects in doped and semi-insulating n-6H-SiC epilayers grown by sublimation method
- 2012
-
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.
|
|
| 5. |
- Ashraf, H., et al.
(författare)
-
Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy
- 2010
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 108:10
-
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.
|
|
| 6. |
- Azam, Sher, et al.
(författare)
-
Comparison of Two GaN Transistor Technologies in Broadband Power Amplifiers
- 2010
-
Ingår i: MICROWAVE JOURNAL. - : Horizon House Publications, Inc.. - 0192-6225. ; 53:4, s. 184-192
-
Tidskriftsartikel (refereegranskat)abstract
- This article compares the performance of two different GaN transistor technologies, GaN HEMT on silicon substrate (PA1) and GaN on SiC (PA2), utilized in two broadband power amplifiers operating at 0.7 to 1.8 GHz. The study explores the broadband power amplifier potential of both GaN HEMT technologies for phased-array radar (PAR) and electronic warfare (EW) systems. The measured maximum output power for PA1 is 42.5 dBm (18 W) with a maximum PAE of 66 percent and a gain of 19.5 dB. The measured maximum output power for PA2 is 40 dBm with a PAE of 37 percent and a power gain slightly above 10 dB. The high power gain, ME, wider bandwidth and unconditional stability was obtained without feedback for the amplifier based on GaN HEMT technology, fabricated on Si substrate.
|
|
| 7. |
|
|
| 8. |
- Bano, Nargis, et al.
(författare)
-
Depth-resolved cathodoluminescence study of zinc oxide nanorods catalytically grown on p-type 4H-SiC
- 2010
-
Ingår i: Journal of Luminescence. - : Elsevier Science B.V., Amsterdam.. - 0022-2313 .- 1872-7883. ; 130:6, s. 963-968
-
Tidskriftsartikel (refereegranskat)abstract
- Optical properties of ZnO nanorods (NRs) grown by vapour-liquid-solid (VLS) technique on 4H-p-SiC substrates were probed by cathodoluminescence (CL) measurements at room temperature and at 5 K complemented with electroluminescence. At room temperature the CL spectra for defect related emission intensity was enhanced with the electron beam penetration depth. We observed a variation in defect related green emission along the nanorod axis. This indicates a relatively poor structural quality near the interface between ZnO NRs and p-SiC substrate. We associate the green emission with oxygen vacancies. Analysis of the low-temperature (5 K) emission spectra in the UV region suggests that the synthesized nanorods contain shallow donors and acceptors.
|
|
| 9. |
- Faraz, Sadia Muniza, et al.
(författare)
-
Annealing Effects on Electrical and Optical Properties of N-ZnO/P-Si Heterojunction Diodes
- 2011
-
Ingår i: <em>Advanced Materials Research Vol. 324 (2011) pp 233-236</em>. - : Trans Tech Publications Inc.. ; , s. 233-236
-
Konferensbidrag (refereegranskat)abstract
- The effects of post fabrication annealing on the electrical characteristics of n-ZnO/p-Si heterostructure are studied. The nanorods of ZnO are grown by aqueous chemical growth (ACG) technique on p-Si substrate and ohmic contacts of Al/Pt and Al are made on ZnO and Si. The devices are annealed at 400 and 600 oC in air, oxygen and nitrogen ambient. The characteristics are studied by photoluminescence (PL), current–voltage (I-V) and capacitance - voltage (C-V) measurements. PL spectra indicated higher ultraviolet (UV) to visible emission ratio with a strong peak of near band edge emission (NBE) centered from 375-380 nm and very weak broad deep-level emissions (DLE) centered from 510-580 nm. All diodes show typical non linear rectifying behavior as characterized by I-V measurements. The results indicated that annealing in air and oxygen resulted in better electrical characteristics with a decrease in the reverse current.
|
|
| 10. |
- Kashif, Ahsan-Ullah, et al.
(författare)
-
A TCAD approach for non-linear evaluation of microwave power transistor and its experimental verification by LDMOS
- 2010
-
Ingår i: Journal of Computational Electronics. - : SpringerLink. - 1569-8025 .- 1572-8137. ; 9:2, s. 79-86
-
Tidskriftsartikel (refereegranskat)abstract
- A simulation technique is developed in TCAD to study the non-linear behavior of RF power transistor. The technique is based on semiconductor transport equations to swot up the overall non-linearity’s occurring in RF power transistor. Computational load-pull simulation technique (CLP) developed in our group, is further extended to study the non-linear effects inside the transistor structure by conventional two-tone RF signals, and initial simulations were done in time domain. The technique is helpful to detect, understand the phenomena and its mechanism which can be resolved and improve the transistor performance. By this technique, the third order intermodulation distortion (IMD3) was observed at different power levels. The technique was successfully implemented on a laterally-diffused field effect transistor (LDMOS). The value of IMD3 obtained is −22 dBc at 1-dB compression point (P 1 dB) while at 10 dB back off the value increases to −36 dBc. Simulation results were experimentally verified by fabricating a power amplifier with the similar LDMOS transistor.
|
|
