| 1. |
- Hussain, Muhammad Waqar, 1985-, et al.
(författare)
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A 500 °C Active Down-Conversion Mixer in Silicon Carbide Bipolar Technology
- 2018
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Ingår i: IEEE Electron Device Letters. - : IEEE Press. - 0741-3106 .- 1558-0563. ; 39:6, s. 855-858
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents an active down-conversion mixer for high-temperature communication receivers. The mixer is based on an in-house developed 4H-SiC BJT and down-converts a narrow-band RF input signal centered around 59 MHz to an intermediate frequency of 500 kHz. Measurements show that the mixer operates from room temperature up to 500 °C. The conversion gain is 15 dB at 25 °C, which decreases to 4.7 dB at 500 °C. The input 1-dB compression point is 1 dBm at 25 °C and −2.5 dBm at 500 °C. The mixer is biased with a collector current of 10 mA from a 20 V supply and has a maximum DC power consumption of 204 mW. High-temperature reliability evaluation of the mixer shows a conversion gain degradation of 1.4 dB after 3-hours of continuous operation at 500 °C.
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| 2. |
- Hussain, Muhammad Waqar, 1985-, et al.
(författare)
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A SiC BJT-Based Negative Resistance Oscillator for High-Temperature Applications
- 2019
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Ingår i: IEEE Journal of the Electron Devices Society. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6734. ; 7:1, s. 191-195
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Tidskriftsartikel (refereegranskat)abstract
- This brief presents a 59.5 MHz negative resistanceoscillator for high-temperature operation. The oscillator employs an in-house 4H-SiC BJT, integrated with the requiredcircuit passives on a low-temperature co-fired ceramic substrate. Measurements show that the oscillator operates from room-temperature up to 400 C. The oscillator delivers an output◦power of 11.2 dBm into a 50 Ω load at 25 C, which decreases to 8.4 dBm at 400 C. The oscillation frequency varies by 3.3% in the entire temperature range. The oscillator is biased witha collector current of 35 mA from a 12 V supply and has amaximum DC power consumption of 431 mW.
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| 3. |
- Hussain, Muhammad Waqar, 1985-, et al.
(författare)
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An Intermediate Frequency Amplifier for High-Temperature Applications
- 2018
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Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9383 .- 1557-9646. ; 65:4, s. 1411-1418
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a two-stage small signal intermediate frequency amplifier for high-temperature communication systems. The proposed amplifier is implemented using in-house silicon carbide bipolar technology. Measurements show that the proposed amplifier can operate from room temperature up to 251 °C. At a center frequency of 54.6 MHz, the amplifier has a gain of 22 dB at room temperature, which decreases gradually to 16 dB at 251 °C. Throughout the measured temperature range, it achieves an input and output return loss of less than-7 and-11 dB, respectively. The amplifier has a 1-dB output compression point of about 1.4 dBm, which remains fairly constant with temperature. Each amplifier stage is biased with a collector current of 10 mA and a base-collector voltage of 3 V. Under the aforementioned biasing, the maximum power dissipation of the amplifier is 221 mW.
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| 4. |
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| 5. |
- Hussain, Muhammad Waqar, 1985-
(författare)
-
High-Temperature Radio Circuits in Silicon Carbide Bipolar Technology
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-temperature electronics find many niche applications in downhole drilling, aviation, automotive and future exploration of inner planets like Venus and Mercury. Past studies have shown the potential of silicon carbide (SiC) electronics for catering these extreme temperature applications. In particular, analog, digital and mixed-signal integrated circuits, based on in-house SiC bipolar technology, have been shown to operate successfully for temperatures as high as 500 oC. This thesis aims at exploring the potential of in-house SiC bipolar technology for realizing high-temperature radio frequency (RF) circuits.To that end, the in-house SiC bipolar junction transistors (BJTs) are first characterized up to 300 oC for RF figures of merit like unity current gain bandwidth and unity power gain bandwidth. The measurement results showed the feasibility of the current batch of SiC BJTs for developing RF circuits operating at low-end of very high frequency (VHF) band. Thereafter, three fundamental blocks of a high-temperature radio receiver, i.e. an intermediate-frequency amplifier, an oscillator and a down-conversion mixer were implemented. Firstly, an intermediate-frequency amplifier has been designed and measurement results demonstrated operation up to 251 oC. The proposed amplifier achieved a gain, input, and output matching of 16 dB, -7.5 dB and -11.2 dB, respectively, at 54.6 MHz and 251 oC. Next, 500 oC operation of an active down-conversion mixer has been exhibited. Measurements have shown that the conversion gain of the proposed mixer is 4.7 dB at 500 oC. Lastly, a negative resistance oscillator has been designed and tested successfully up to 400 oC. It has been shown that at 400 oC, the proposed oscillator delivers an output power of 8.4 dBm into a 50 Ω load.In addition to SiC BJTs, the aforementioned circuits also employed spiral inductors implemented on PCBs, commercially available ceramic capacitors and thick-film resistors. Therefore, this thesis presents the evaluation of passives to assess their feasibility for high temperature operation. This work also identifies and addresses several challenges associated with the development flow of high-temperature RF circuits.
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| 6. |
- Hussain, Muhammad Waqar, 1985-, et al.
(författare)
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Modeling Temperature Dependence of fT in 4H-SiC Bipolar Transistors
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper models the temperature dependence of fT in 4H-SiC bipolar devices. The proposed model describes variation of the constituent parameters of fT as a function of temperature. The model assumes complete ionization of dopants in 4H-SiC. However, this assumption hampers the model’s utilityat temperatures below 300◦C. The model was simulated attemperatures between 300◦C and 700◦C and a drop in fT wasobserved. However, measurements are required to prove thecorrectness of the model or lack thereof.
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| 7. |
- Hussain, Muhammad Waqar, 1985-, et al.
(författare)
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Silicon Carbide BJT Oscillator Design Using S-Parameters
- 2018
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Ingår i: European Conference on Silicon Carbide and Related Materials (ECSCRM), Birmingham September 2-6, 2018..
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Konferensbidrag (refereegranskat)abstract
- Radio frequency (RF) oscillator design typically requires large-signal, high-frequency simulation models for the transistors. The development of such models is generally difficult and time consuming due to a large number of measurements needed for parameter extraction. The situation isfurther aggravated as the parameter extraction process has to be repeated at multiple temperature points in order to design a wide-temperature range oscillator. To circumvent this modelling effort, analternative small-signal, S-parameter based design method can be employed directly without goinginto complex parameter extraction and model fitting process. This method is demonstrated through design and prototyping a 58 MHz, high-temperature (HT) oscillator, based on an in-house 4H-SiC BJT. The BJT at elevated temperature (up to 300 0C) was accessed by on-wafer probing and connectedby RF-cables to the rest of circuit passives, which were kept at room temperature (RT).
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| 8. |
- Hussain, Muhammad Waqar, 1985-, et al.
(författare)
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Silicon carbide BJT oscillator design using S-parameters
- 2019
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Ingår i: Silicon Carbide and Related Materials 2018. - : Trans Tech Publications Ltd. ; , s. 674-678
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Konferensbidrag (refereegranskat)abstract
- Radio frequency (RF) oscillator design typically requires large-signal, high-frequency simulation models for the transistors. The development of such models is generally difficult and time consuming due to a large number of measurements needed for parameter extraction. The situation is further aggravated as the parameter extraction process has to be repeated at multiple temperature points in order to design a wide-temperature range oscillator. To circumvent this modelling effort, an alternative small-signal, S-parameter based design method can be employed directly without going into complex parameter extraction and model fitting process. This method is demonstrated through design and prototyping a 58 MHz, high-temperature (HT) oscillator, based on an in-house 4H-SiC BJT. The BJT at elevated temperature (up to 300 °C) was accessed by on-wafer probing and connected by RF-cables to the rest of circuit passives, which were kept at room temperature (RT).
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