Mahmoud Mehdi | Lebanese University (original) (raw)

Papers by Mahmoud Mehdi

International Journal of Electrical and Computer Engineering (IJECE)

A 5G mm-wave monolithic microwave integrated circuit (MMIC) voltage-controlled oscillator (VCO) i... more A 5G mm-wave monolithic microwave integrated circuit (MMIC) voltage-controlled oscillator (VCO) is presented in this paper. It is designed on GaAs substrate and with 0.25 µm-pHEMT technology from UMS foundry and it is based on pHEMT varactors in order to achieve a very small chip size. A 0dBm-output power over the entire tuning range from 27.67 GHz to 28.91 GHz, a phase noise of -96.274 dBc/Hz and -116.24 dBc/Hz at 1 and 10 MHz offset frequency from the carrier respectively are obtained on simulation. A power consumption of 111 mW is obtained for a chip size of 0.268 mm2. According to our knowledge, this circuit occupies the smallest surface area compared to pHEMTs oscillators published in the literature.

Terahertz Wireless Communication Components and System Technologies, 2022

Proceedings of the 2nd International Conference on Big Data, Modelling and Machine Learning

International Journal on Communications Antenna and Propagation (IRECAP)

A new topology of a dual-band active bandpass filter is presented in this paper. This structure c... more A new topology of a dual-band active bandpass filter is presented in this paper. This structure consists of two transconductances constituting the active inductor, which represents the core of the filter and which is responsible for delivering the resonance frequency of the filter, connected at its input to a varactor used to tune the centre frequency. The two peaks of the dual-band filter can be tuned in frequency while maintaining the same power of gain and the same bandwidth. Good out-of-band rejection is observed of -13 dB and -11 dB on both bands with a very high quality factor that exceeds 1500.The filter is designed for 5G applications around 28GHz and 38 GHz and for satellite uplinks.

2020 1st International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET), 2020

A customized structure of the Colpitts VCO for the 5G millimeter band is presented in this paper,... more A customized structure of the Colpitts VCO for the 5G millimeter band is presented in this paper, this structure has a very low phase noise level compared to other structures published in the literature. Simulation results show that our VCO has a tuning range of 1.69 GHz around 28 GHz, an output power of 3.3 dBm and a phase noise around -123.2dBc/Hz at 1 MHz offset frequency from carrier. The VCO is designed in MMIC technology using the pHEMT transistor of PH15 process from UMS foundry.

Embedded Systems and Artificial Intelligence, 2020

Ultra-wideband (UWB) radars are used for several applications such as locating, detecting and pre... more Ultra-wideband (UWB) radars are used for several applications such as locating, detecting and preventing collisions. The detection of humans hidden by walls or trapped in burning buildings or avalanche victims is so important. In our research, we aim to design UWB radar to meet those needs. In this paper, we study monostatic and bistatic radars in order to form a general idea about the process of implementation of a radar information processing chain, before adapting it to the UWB technology that will be used in our application later on. The application which consists in detecting and locating targets through walls.

2019 7th Mediterranean Congress of Telecommunications (CMT), 2019

this paper presents a new electromagnetic aspect of the antenna matrix which concerns the realiza... more this paper presents a new electromagnetic aspect of the antenna matrix which concerns the realization of high gains by using radiating pixels with large dimensions greater than (0.8λ × 0.8λ). The electromagnetic advantages are shown through a comparative study made between a 1D matrix antenna and a conventional linear antenna array. Comparison concerns bandwidth, radiating surfaces, surface efficiency and grating lobes. The comparison shows the possibility of eliminating grating lobes with large matrix antenna thus breaking the periodicity of conventional arrays.

In this paper, a 60 GHz high efficiency power amplifier (PA) with integrated input and output mat... more In this paper, a 60 GHz high efficiency power amplifier (PA) with integrated input and output matching is presented. The designed PA uses a 0.15 μm gate length AsGa PHEMT (Pseudomorphic High Electron Mobility Transistor) process. The power amplifier achieves a peak power gain of 17.8 dB and a maximum single-ended output power of 14.34 dBm with 57.95% of power-added efficiency (PAE) at 60 GHz. These results are the best combination of output power and efficiency reported for an MMIC (Monolithic Microwave Integrated Circuit) AsGa device at V-band. The designed power amplifier has a 3-dB bandwidth of 7 GHz.

In this paper, we verify the potentiality of common-gate configuration as an active impedance mat... more In this paper, we verify the potentiality of common-gate configuration as an active impedance matching to improve performance of PHEMT frequency multiplier by 4. A 8.87% relative bandwidth at millimeter wave frequencies for frequency multiplier by 4 is achieved by this technique. In this contribution, simulation results show the good impact of this technique on the performance of PHEMT frequency multiplier by 4 especially on the conversion gain and output power.

A mixture mixing an intermediate frequency signal FI device with a carrier signal from a local os... more A mixture mixing an intermediate frequency signal FI device with a carrier signal from a local oscillator OL to produce an output signal mainly comprising a component in the high radio frequency RF sideband, the lower sideband component and the OL and IF frequency components being removed. To do this, the device according to the invention comprises two phase shifting lines supplied by the intermediate frequency signal and the carrier signal. Each phase line successively generates four phase shifted by -90 ° signals. These phase shifted signals pass through a set of mixers, couplers and phase shifters so as not to obtain at the output a component at the RF frequency.

World Academy of Science, Engineering and Technology, International Journal of Electronics and Communication Engineering, 2015

This paper relates the new topology and simulations of a fully differential CMOS active filter fo... more This paper relates the new topology and simulations of a fully differential CMOS active filter for mm wave band applications. The advantages of the differential topology over the single ended one are discussed and the quality factor is tuned to insure application requirements, including narrow bandwidth and high selectivity due to a differential negative resistance that reuses the filter’s current. Using this topology enables independent tuning of the quality factor and low power consumption while compensating the resistive loss of the filter. Very high filter performance was obtained with the simulated active inductor based active filter that was designed using CMOS 0.35 µm technology from AMS foundry and that resonates at 30 GHz with a high quality factor of Q > 500.

World Academy of Science, Engineering and Technology, International Journal of Electronics and Communication Engineering, 2015

In this paper, a three-stage cascode LNA and a three-stage common source LNA are presented. A com... more In this paper, a three-stage cascode LNA and a three-stage common source LNA are presented. A comparison in terms of noise figure and gain between the two designed three-stage MMIC common source and cascode LNAs is discussed. This LNAs will be used as a part of a WPAN (Wirless Personal Area Network) receiver in the millimeter-wave band at 60 GHz. These low noise amplifiers are designed according to the MMIC technology (Monolithic Microwave Integrated Circuit) in PH15 process from UMS foundry and uses a 0.15 μ m GaAs PHEMT ( Pseudomorphic High Electron Mobility Transistor). The three-stage cascode LNA shows better performances compared to the three-stage common source LNA. The proposed three-stage cascode LNA exhibits a very low noise figure which is equal to 1dB and a high gain which is about 23 dB. An input return loss of -6.61 dB and an output return loss of -11.26 dB are also achieved by this LNA.

Advances in Science, Technology and Engineering Systems Journal, 2020

Oscillator phase noise (PN) has a strong impact on the spectral purity of the RF signal in wirele... more Oscillator phase noise (PN) has a strong impact on the spectral purity of the RF signal in wireless systems and is, therefore, a main challenge when designing a local oscillator. In this paper, we propose a new approach for designing a low PN oscillator based on the Time-Invariant Linear Model of phase noise. It leads on voltage-controlled oscillator (VCO) simulated good performances: a low phase noise (PN) near-123.2 dBc/Hz@1MHz offset from the carrier, an output power of 3.26 dBm, and an output signal frequency ranging from 27.98 GHz to 29.67 GHz. Low power-consumption (51mW) and small size (0.237 mm 2) benefit from MMIC UMS foundry (United Monolithic Semiconductors) and 0.15 µm-pHEMT GaAs technology.

International Journal of Electrical and Computer Engineering (IJECE), 2020

This paper presents the study and design of a balanced voltage controlled oscillator VCO for 5G w... more This paper presents the study and design of a balanced voltage controlled oscillator VCO for 5G wireless communication systems. This circuit is designed in monolithic microwave integrated circuit (MMIC) technology using PH15 process from UMS foundry. The VCO ensures an adequate tuning range by a single-ended pHEMT varactors configuration. The simulation results show that this circuit delivers a sinusoidal signal of output power around 9 dBm with a second harmonic rejection between 25.87 and 33.83 dB, the oscillation frequency varies between 26.46 and 28.90 GHz, the phase noise is -113.155 and -133.167 dBc/Hz respectively at 1 MHz and 10 MHz offset and the Figure of Merit is -181.06 dBc/Hz. The power consumed by the VCO is 122 mW. The oscillator layout with bias and RF output pads occupies an area of 0.515 mm2.

International Journal on Communications Antenna and Propagation (IRECAP), 2016

This paper discusses the nonlinear behavior of the transconductance of a GaAs PHEMT device and it... more This paper discusses the nonlinear behavior of the transconductance of a GaAs PHEMT device and its dependence with the harmonic generation. The analytic study and simulations show that when the gate bias is close to the pinch-off voltage, the transconductance is zero and the extracting of the even harmonics occurs, besides, when this bias is around 0 V, the transconductance is maximized and the odd harmonics are generated. As an example to validate this dependence, a frequency quadrupler based on 0.15 μm PHEMT from UMS foundry using ADS software from Agilent is presented in this work.

Contemporary Engineering Sciences, 2017

The modern telecommunication systems such as mobile radio network, wireless and satellites requir... more The modern telecommunication systems such as mobile radio network, wireless and satellites require the use of tunable high selective filters with a high quality factor Q. Unlike large sized passive filters whose frequency is difficult to tune, active inductor based filters have lots of benefits such as electronic frequency tuning, simplicity of integration and minimizing size. However, the intrinsic losses of the transistors limit the quality factor and the energy consumption remains significant. To remedy, various techniques exist in literature to boost Q including biasing conditions optimization in order to save energy and improve the quality factor of the filter. The centre frequency tuning requires varactors widely used in filtering and low noise amplifier circuits. In this way the frequency may be varied without affecting the quality factor of the filter. In this paper an active filter using 0.15 µm PHEMT technology is proposed with a centre frequency of 38 GHz for use in the next 5 generation of mobile network system. The aforementioned filter presents a high quality factor, a very good out-of-band rejection 194 Imane Halkhams et al. and very low noise figure. This filter will be used in the implementation of high frequency transceivers in the millimetre band.

Lecture Notes in Electrical Engineering, 2016

This paper presents a V-band buffer amplifier based on 0.15 µm pHEMT from UMS foundry for WPAN ap... more This paper presents a V-band buffer amplifier based on 0.15 µm pHEMT from UMS foundry for WPAN applications. This amplifier will be used as a part of a frequency quadrupler in the millimeter wave band at 60 GHz. The amplifier circuit can deliver a gain up to 13 dB at 60 GHz with a low noise figure of 2.4 dB. An input return loss of 18 dB and an output return loss of 10 dB are also achieved by this amplifier. The input P1 dB and IP3 are 0.3 and 27 dBm respectively.

International Journal of Electrical and Computer Engineering (IJECE)

A 5G mm-wave monolithic microwave integrated circuit (MMIC) voltage-controlled oscillator (VCO) i... more A 5G mm-wave monolithic microwave integrated circuit (MMIC) voltage-controlled oscillator (VCO) is presented in this paper. It is designed on GaAs substrate and with 0.25 µm-pHEMT technology from UMS foundry and it is based on pHEMT varactors in order to achieve a very small chip size. A 0dBm-output power over the entire tuning range from 27.67 GHz to 28.91 GHz, a phase noise of -96.274 dBc/Hz and -116.24 dBc/Hz at 1 and 10 MHz offset frequency from the carrier respectively are obtained on simulation. A power consumption of 111 mW is obtained for a chip size of 0.268 mm2. According to our knowledge, this circuit occupies the smallest surface area compared to pHEMTs oscillators published in the literature.

Terahertz Wireless Communication Components and System Technologies, 2022

Proceedings of the 2nd International Conference on Big Data, Modelling and Machine Learning

International Journal on Communications Antenna and Propagation (IRECAP)

A new topology of a dual-band active bandpass filter is presented in this paper. This structure c... more A new topology of a dual-band active bandpass filter is presented in this paper. This structure consists of two transconductances constituting the active inductor, which represents the core of the filter and which is responsible for delivering the resonance frequency of the filter, connected at its input to a varactor used to tune the centre frequency. The two peaks of the dual-band filter can be tuned in frequency while maintaining the same power of gain and the same bandwidth. Good out-of-band rejection is observed of -13 dB and -11 dB on both bands with a very high quality factor that exceeds 1500.The filter is designed for 5G applications around 28GHz and 38 GHz and for satellite uplinks.

2020 1st International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET), 2020

A customized structure of the Colpitts VCO for the 5G millimeter band is presented in this paper,... more A customized structure of the Colpitts VCO for the 5G millimeter band is presented in this paper, this structure has a very low phase noise level compared to other structures published in the literature. Simulation results show that our VCO has a tuning range of 1.69 GHz around 28 GHz, an output power of 3.3 dBm and a phase noise around -123.2dBc/Hz at 1 MHz offset frequency from carrier. The VCO is designed in MMIC technology using the pHEMT transistor of PH15 process from UMS foundry.

Embedded Systems and Artificial Intelligence, 2020

Ultra-wideband (UWB) radars are used for several applications such as locating, detecting and pre... more Ultra-wideband (UWB) radars are used for several applications such as locating, detecting and preventing collisions. The detection of humans hidden by walls or trapped in burning buildings or avalanche victims is so important. In our research, we aim to design UWB radar to meet those needs. In this paper, we study monostatic and bistatic radars in order to form a general idea about the process of implementation of a radar information processing chain, before adapting it to the UWB technology that will be used in our application later on. The application which consists in detecting and locating targets through walls.

2019 7th Mediterranean Congress of Telecommunications (CMT), 2019

this paper presents a new electromagnetic aspect of the antenna matrix which concerns the realiza... more this paper presents a new electromagnetic aspect of the antenna matrix which concerns the realization of high gains by using radiating pixels with large dimensions greater than (0.8λ × 0.8λ). The electromagnetic advantages are shown through a comparative study made between a 1D matrix antenna and a conventional linear antenna array. Comparison concerns bandwidth, radiating surfaces, surface efficiency and grating lobes. The comparison shows the possibility of eliminating grating lobes with large matrix antenna thus breaking the periodicity of conventional arrays.

In this paper, a 60 GHz high efficiency power amplifier (PA) with integrated input and output mat... more In this paper, a 60 GHz high efficiency power amplifier (PA) with integrated input and output matching is presented. The designed PA uses a 0.15 μm gate length AsGa PHEMT (Pseudomorphic High Electron Mobility Transistor) process. The power amplifier achieves a peak power gain of 17.8 dB and a maximum single-ended output power of 14.34 dBm with 57.95% of power-added efficiency (PAE) at 60 GHz. These results are the best combination of output power and efficiency reported for an MMIC (Monolithic Microwave Integrated Circuit) AsGa device at V-band. The designed power amplifier has a 3-dB bandwidth of 7 GHz.

In this paper, we verify the potentiality of common-gate configuration as an active impedance mat... more In this paper, we verify the potentiality of common-gate configuration as an active impedance matching to improve performance of PHEMT frequency multiplier by 4. A 8.87% relative bandwidth at millimeter wave frequencies for frequency multiplier by 4 is achieved by this technique. In this contribution, simulation results show the good impact of this technique on the performance of PHEMT frequency multiplier by 4 especially on the conversion gain and output power.

A mixture mixing an intermediate frequency signal FI device with a carrier signal from a local os... more A mixture mixing an intermediate frequency signal FI device with a carrier signal from a local oscillator OL to produce an output signal mainly comprising a component in the high radio frequency RF sideband, the lower sideband component and the OL and IF frequency components being removed. To do this, the device according to the invention comprises two phase shifting lines supplied by the intermediate frequency signal and the carrier signal. Each phase line successively generates four phase shifted by -90 ° signals. These phase shifted signals pass through a set of mixers, couplers and phase shifters so as not to obtain at the output a component at the RF frequency.

World Academy of Science, Engineering and Technology, International Journal of Electronics and Communication Engineering, 2015

This paper relates the new topology and simulations of a fully differential CMOS active filter fo... more This paper relates the new topology and simulations of a fully differential CMOS active filter for mm wave band applications. The advantages of the differential topology over the single ended one are discussed and the quality factor is tuned to insure application requirements, including narrow bandwidth and high selectivity due to a differential negative resistance that reuses the filter’s current. Using this topology enables independent tuning of the quality factor and low power consumption while compensating the resistive loss of the filter. Very high filter performance was obtained with the simulated active inductor based active filter that was designed using CMOS 0.35 µm technology from AMS foundry and that resonates at 30 GHz with a high quality factor of Q > 500.

World Academy of Science, Engineering and Technology, International Journal of Electronics and Communication Engineering, 2015

In this paper, a three-stage cascode LNA and a three-stage common source LNA are presented. A com... more In this paper, a three-stage cascode LNA and a three-stage common source LNA are presented. A comparison in terms of noise figure and gain between the two designed three-stage MMIC common source and cascode LNAs is discussed. This LNAs will be used as a part of a WPAN (Wirless Personal Area Network) receiver in the millimeter-wave band at 60 GHz. These low noise amplifiers are designed according to the MMIC technology (Monolithic Microwave Integrated Circuit) in PH15 process from UMS foundry and uses a 0.15 μ m GaAs PHEMT ( Pseudomorphic High Electron Mobility Transistor). The three-stage cascode LNA shows better performances compared to the three-stage common source LNA. The proposed three-stage cascode LNA exhibits a very low noise figure which is equal to 1dB and a high gain which is about 23 dB. An input return loss of -6.61 dB and an output return loss of -11.26 dB are also achieved by this LNA.

Advances in Science, Technology and Engineering Systems Journal, 2020

Oscillator phase noise (PN) has a strong impact on the spectral purity of the RF signal in wirele... more Oscillator phase noise (PN) has a strong impact on the spectral purity of the RF signal in wireless systems and is, therefore, a main challenge when designing a local oscillator. In this paper, we propose a new approach for designing a low PN oscillator based on the Time-Invariant Linear Model of phase noise. It leads on voltage-controlled oscillator (VCO) simulated good performances: a low phase noise (PN) near-123.2 dBc/Hz@1MHz offset from the carrier, an output power of 3.26 dBm, and an output signal frequency ranging from 27.98 GHz to 29.67 GHz. Low power-consumption (51mW) and small size (0.237 mm 2) benefit from MMIC UMS foundry (United Monolithic Semiconductors) and 0.15 µm-pHEMT GaAs technology.

International Journal of Electrical and Computer Engineering (IJECE), 2020

This paper presents the study and design of a balanced voltage controlled oscillator VCO for 5G w... more This paper presents the study and design of a balanced voltage controlled oscillator VCO for 5G wireless communication systems. This circuit is designed in monolithic microwave integrated circuit (MMIC) technology using PH15 process from UMS foundry. The VCO ensures an adequate tuning range by a single-ended pHEMT varactors configuration. The simulation results show that this circuit delivers a sinusoidal signal of output power around 9 dBm with a second harmonic rejection between 25.87 and 33.83 dB, the oscillation frequency varies between 26.46 and 28.90 GHz, the phase noise is -113.155 and -133.167 dBc/Hz respectively at 1 MHz and 10 MHz offset and the Figure of Merit is -181.06 dBc/Hz. The power consumed by the VCO is 122 mW. The oscillator layout with bias and RF output pads occupies an area of 0.515 mm2.

International Journal on Communications Antenna and Propagation (IRECAP), 2016

This paper discusses the nonlinear behavior of the transconductance of a GaAs PHEMT device and it... more This paper discusses the nonlinear behavior of the transconductance of a GaAs PHEMT device and its dependence with the harmonic generation. The analytic study and simulations show that when the gate bias is close to the pinch-off voltage, the transconductance is zero and the extracting of the even harmonics occurs, besides, when this bias is around 0 V, the transconductance is maximized and the odd harmonics are generated. As an example to validate this dependence, a frequency quadrupler based on 0.15 μm PHEMT from UMS foundry using ADS software from Agilent is presented in this work.

Contemporary Engineering Sciences, 2017

The modern telecommunication systems such as mobile radio network, wireless and satellites requir... more The modern telecommunication systems such as mobile radio network, wireless and satellites require the use of tunable high selective filters with a high quality factor Q. Unlike large sized passive filters whose frequency is difficult to tune, active inductor based filters have lots of benefits such as electronic frequency tuning, simplicity of integration and minimizing size. However, the intrinsic losses of the transistors limit the quality factor and the energy consumption remains significant. To remedy, various techniques exist in literature to boost Q including biasing conditions optimization in order to save energy and improve the quality factor of the filter. The centre frequency tuning requires varactors widely used in filtering and low noise amplifier circuits. In this way the frequency may be varied without affecting the quality factor of the filter. In this paper an active filter using 0.15 µm PHEMT technology is proposed with a centre frequency of 38 GHz for use in the next 5 generation of mobile network system. The aforementioned filter presents a high quality factor, a very good out-of-band rejection 194 Imane Halkhams et al. and very low noise figure. This filter will be used in the implementation of high frequency transceivers in the millimetre band.

Lecture Notes in Electrical Engineering, 2016

This paper presents a V-band buffer amplifier based on 0.15 µm pHEMT from UMS foundry for WPAN ap... more This paper presents a V-band buffer amplifier based on 0.15 µm pHEMT from UMS foundry for WPAN applications. This amplifier will be used as a part of a frequency quadrupler in the millimeter wave band at 60 GHz. The amplifier circuit can deliver a gain up to 13 dB at 60 GHz with a low noise figure of 2.4 dB. An input return loss of 18 dB and an output return loss of 10 dB are also achieved by this amplifier. The input P1 dB and IP3 are 0.3 and 27 dBm respectively.