Ahmed Sayed

Two-stage ultrawide-band 5-W power amplifier using SiC MESFET

This paper describes a two-stage 5-W broad-band amplifier covering the frequency range from 10 MHz to 2.4 GHz. An SiC MESFET is used as the power stage. A large-signal table-based model has been developed and verified for the SiC device by comparison with measurements. A novel broad-band choke structure was developed to obtain high dc isolation and low RF loss over the full bandwidth. No impedance transformer was used at all. Broad-band input and output matching networks and shunt feedback topology were introduced to fulfill the bandwidth requirements. Typical values of 22-dB power gain, 37-dBm output power, 28% power-added efficiency, and 47-dBm third-order intercept points have been achieved in a two-stage design using a GaAs MESFET as driver stage. All power and linearity results were obtained over the whole frequency band. The design procedure is given in detail and the results are being discussed and compared with simulations.

Broadband GaN switch mode class E power amplifier for UHF applications

In this work a broad-band class E power amplifier (PA) is designed, manufactured and measured. 400 MHz bandwidth with a center frequency of 800 MHz was realized using a GaN HEMT device. A novel and easy circuit topology is proposed for broad-band bandpass filter with integrated output matching network. Different filter types are discussed, suitable topology is chosen and design equations are shown. A maximum drain efficiency of 87.8 % (PAE = 80.6 %) is observed. Maximum output power of 49 W is measured with 16.3 dB power gain at the 1 dB compression point.

Novel Broadband Wilkinson Power Combiner

This paper describes a new hybrid wideband architecture of a two-stage Wilkinson power combiner/divider using additional capacitive and inductive elements in both stages. The combiner/divider shows a bandwidth from 0.3 GHz up to 2.8 GHz with an insertion loss of less than 0.2 dB and an isolation of about 10 dB. The new combiner topology, design process and results are being discussed

5W highly linear GaN power amplifier with 3.4 GHz bandwidth

In this paper, a 1 MHz to 3.4 GHz, 5 W, highly linear power amplifier based on GaN HEMT is reported. Load-pull technique has been applied to introduce a compromising solution for the PA performance trade-off problem. Over the whole bandwidth a measured small signal gain of 14 plusmn 0.7 dB and an output return loss of better than -10 dB have been achieved. The input return loss was better than -10 dB up to 3 GHz. Power and linearity performances have been measured and compared to simulations resulting in a very good agreement. At a frequency spacing of 100 kHz, minimum values of output IP3 and output IP2 have been evaluated and found to be 48.5 dBm and 59.3 dBm. At 1 dB power compression point, minimum Pout, and Gp were found to be ges37.3 dBm and ges13.3 dB, respectively within the whole frequency band.

A 2.14 GHz 50 Watt 60% Power Added Efficiency GaN Current Mode Class D Power Amplifier

This paper presents a 50 W current mode class D (CMCD) power amplifier (PA) operating at 2.14 GHz. The PA is implemented using GaN pHEMT. The peak drain efficiency (iquest) is 62.7% and power added efficiency (PAE) is 60.3%. A resonator without an inductor was implemented to eliminate any loss that results from the low quality factors. The resonator uses narrow microstrip DC-feed lines located close to the drain leads which is used as resonator inductance. A model of the output capacitance (i.e.; Cds) was extracted from the die model and is used as a part of the resonator. Finally, a comparison between an ideal parallel LC with the proposed resonator was simulated to achieve the required impedance termination.

An enhanced empirical large signal model of SiC MESFETs for power applications

In this paper, a large signal table-based model for SiC MESFET is presented. A packaged commercially available high power MESFET device (CREE CRF24010) is adopted for the model development. The extracted bias-dependent elements of the small signal model as well as the measured DC data are mathematically described by small modification of Angelovs formulation. Dispersion between DC and RF characteristics of the drain current is also observed and interpreted. The new model is capable to predict small signal as well as large signal performance accurately. A single stage ultra broadband 5 W power amplifier has been developed to verify the derived model. A good agreement has been obtained between simulated and measured results.

Design of Class F -1 Power Amplifier Using GaN pHEMT for Industrial Applications

This work presents a Class F-1 power amplifier (PA) operating at 2.35 GHz. An output power of 40 W (46 dBm) was achieved with 10 dB gain. The maximum drain efficiency was measured to be 60.8 % (PAE = 55.7 %). The power amplifier was implemented using GaN pHEMT. The realization of the optimum load resonator was designed by a microstrip resonator, for the first four harmonics. The resonator achieves an optimum load for the transistor at the fundamental frequency.

Reference Plane Transformation of Continuous Mode Terminations for Broadband Power Amplifiers

Abstract In this article the behavior of continuous mode amplifiers at different reference planes is discussed using the example of a continuous class-F−1 amplifier mode. The variation of the output impedances and the conversion of the output voltage and current waveforms are analyzed depending on the considered reference plane. For instance, the frequently discussed current source reference plane has a way different impedance characteristic than the accessible lead reference plane. In order to study this aspect, a broadband continuous class-F−1 mode amplifier has been realized using a bare-die GaN-HEMT. From 1.0 to 1.8 GHz, this amplifier attains 44.5–45.2 dBm output power with corresponding drain efficiency of 65–68%.

ANALYSIS OF BROADBAND GAN SWITCH MODE CLASS-E POWER AMPLIFIER

Switch mode power amplifiers offer high efficiency approaching 100 % for an ideal case. This paper discusses the operation mode of broadband switch mode class-E power amplifier designed previously by the authors for UHF applications (600 – 1000 MHz). A method to extract the waveforms at the die reference plane from the time domain analysis using 50 Ω environment system is discussed. It has been observed that the designed class-E power amplifier operation was not maintained ideally over the entire band, however, it was operating close to the class-E operation.

A 6W Uneven LDMOS Doherty Power Amplifier With High Efficiency for GSM900 Base Stations

In this paper, a 6W uneven LDMOS Doherty power amplifier (DPA), designed for GSM900 base stations, which implement phased antenna array transmission, is presented. The designed Doherty PA can deliver a maximum power of 6.5W. A high drain efficiency of ¿=64% (PAE=58%) is measured. The efficiency is maintained above ¿=43% (PAE=37%), over 6-dB output backoff, and above ¿=31% (PAE=29%), over 9-dB output backoff, related to the maximum (saturated) power.