Paul Saad

Design of a Concurrent Dual-Band 1.8–2.4-GHz GaN-HEMT Doherty Power Amplifier

In this paper, the design, implementation, and experimental results of a high-efficiency dual-band GaN-HEMT Doherty power amplifier (DPA) are presented. An extensive discussion about the design of the passive structures is presented showing different possible topologies of the dual-band DPA. One of the proposed topologies is used to design a dual-band DPA in hybrid technology for the frequency bands 1.8 and 2.4 GHz with the second efficiency peak at 6-dB output power back-off (OBO). For a continuous-wave output power of 20 W, the measured power-added efficiency (PAE) is 64% and 54% at 1.8 and 2.4 GHz, respectively. At -dB OBO, the resulting measured PAEs were 60% and 44% in the two frequency bands. Linearized concurrent modulated measurement using 10-MHz LTE signal with 7-dB peak-to-average-ratio (PAR) at 1.8 GHz and 10-MHz WiMAX signal with 8.5-dB PAR at 2.4 GHz shows an average PAE of 34%, at an adjacent channel leakage ratio of -48 dBc and -46 dBc at 1.8 and 2.4 GHz, respectively.

Design of a Highly Efficient 2–4-GHz Octave Bandwidth GaN-HEMT Power Amplifier

In this paper, the design, implementation, and experimental results of a high-efficiency wideband GaN-HEMT power amplifier are presented. A method based on source-pull/load-pull simulation has been used to find optimum source and load impedances across the bandwidth and then used with a systematic approach to design wideband matching networks. Large-signal measurement results show that, across 1.9-4.3 GHz, 9-11-dB power gain and 57%-72% drain efficiency are obtained while the corresponding power-added efficiency (PAE) is 50%-62%. Moreover, an output power higher than 10 W is maintained over the band. Linearized modulated measurements using a 20-MHz long-term evolution signal with 11.2-dB peak-to-average ratio show an average PAE of 27% and 25%, an adjacent channel leakage ratio of -44 and -42 dBc at 2.5 and 3.5 GHz, respectively.

An RF Carrier Bursting System Using Partial Quantization Noise Cancellation

This paper introduces a method for bandpass cancellation of the quantization noise occurring in high efficiency, envelope pulsed transmitter architectures-or carrier bursting. An equivalent complex baseband model of the proposed system, including the -modulator and cancellation signal generation, is developed. Analysis of the baseband model is performed, leading to analytical expressions of the power amplifier drain efficiency, assuming the use of an ideal class B power amplifier. These expressions are further used to study the impact of key system parameters, i.e. the compensation signal variance and clipping probability, on the class B power amplifier drain efficiency and signal-to-noise ratio. The paper concludes with simulations followed by practical measurements in order to validate the functionality of the method and to evaluate the performance-trend predictions made by the theoretical framework in terms of efficiency and spectral purity.

Branch-Line Coupler Design Operating in Four Arbitrary Frequencies

This letter presents a successful design approach for a branch-line coupler operating in four arbitrary frequencies. An optimized compensation technique is adopted to fulfill satisfactory matching, transmission and isolation properties within each operating band. Based on the simple planar microstrip technology, the proposed quad-band coupler has been realized and tested. A return loss better than 16 dB, together with an amplitude imbalance limited to 0.3 dB and an isolation higher than 17.5 dB, have been experimentally measured on each operating band, validating the proposed design methodology.

Concurrent dual-band GaN-HEMT power amplifier at 1.8 GHz and 2.4 GHz

This paper presents the design, implementation, and experimental results of a highly efficient concurrent dual-band GaN-HEMT power amplifier at 1.8 GHz and 2.4 GHz. A bare-die approach, in conjunction with a harmonic source-pull/load-pull simulation approach, are used in order to design and implement the harmonically tuned dual-band PA. For a continuous wave output power of 42.3 dBm the measured gain is 12 dB in the two frequency bands; while the power added efficiency is 64% in both bands. Linearized modulated measurements, using concurrently 10 MHz LTE and WiMAX signals, show an average PAE of 25% and and adjacent channel leakage ratio of -48 dBc and -47 dBc at 1.8 GHz and 2.4 GHz, respectively.

Highly efficient GaN-HEMT power amplifiers at 3.5 GHz and 5.5 GHz

This paper reports the design, implementation, and experimental results of two high efficiency GaN-HEMT power amplifiers (PAs) at 3.5 GHz and 5.5 GHz. A bare-die approach is used to eliminate package parasitics in conjunction with an in-house transistor model that enables investigation of the transistor intrinsic waveforms. With this as a basis, harmonic source-pull/load-pull simulations have been used to design and implement two state-of-the-art highly efficient harmonically tuned PAs. For the 3.5-GHz PA, large-signal measurement results show a PAE of 80%, a power gain of 15.5 dB, and an output power of 7 W, while for the 5.5-GHz PA, 5.6 W output power, 12.5 dB power gain, and 70% PAE are achieved.

High-Efficiency Power Amplifier

In this article, the design of a high-efficiency harmonically tuned GaN HEMT PA has been presented. The PA presents state-of-the-art measured efficiency and gain performance at 3.5 GHz, demonstrating the success of the dedicated transistor modeling, the bare-die mounting and implementation technique, and the circuit design methodology.

A highly efficient 3.5 GHz inverse class-F GaN HEMT power amplifier

This paper presents the design and implementation of an inverse class-F power amplifier (PA) using a high power gallium nitride high electron mobility transistor (GaN HEMT). For a 3.5 GHz continuous wave signal, the measurement results show state-of-the-art power-added efficiency (PAE) of 78%, a drain efficiency of 82%, a gain of 12 dB, and an output power of 12 W. Moreover, over a 300 MHz bandwidth, the PAE and output power are maintained at 60% and 10 W, respectively. Linearized modulated measurements using 20 MHz bandwidth long-term evolution (LTE) signal with 11.5 dB peak-to-average ratio show that 242 dBc adjacent channel power ratio (ACLR) is achieved, with an average PAE of 30%, 247 dBc ACLR with an average PAE of 40% are obtained when using a WCDMA signal with 6.6 dB peak-to-average ratio (PAR).

Highly efficient and wideband harmonically tuned GaN-HEMT power amplifier

In this paper, the design of a highly efficient 25 W GaN-HEMT power amplifier (PA), operating in 1.7 - 2.3 GHz, is presented. The influence of the harmonics and the impact of the parasitic components of the nonlinear device are considered in order to ensure an accurate matching network design to achieve high efficiency. Optimum fundamental and harmonic load impedances were obtained using load-pull simulations across the operation band. From continuous wave large-signal measurements, an average output power of 44 dBm was obtained over the bandwidth. The corresponding drain efficiency ranged between 73 - 80 % with a gain of 12 dB. Linearized modulated measurement, using 10 MHz LTE signal with 7.3 dB peak-to-average-power-ratio (PAPR), shows an average power-added-efficiency (PAE) of 38.2 % and adjacent channel leakage ratio (ACLR) of almost -45 dBc at 1.8 GHz.

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%.