Elisa Cipriani

Optimization of Class E Power Amplifier Design above Theoretical Maximum Frequency

In this contribution, the analysis on high frequency class E design approach is presented. Starting from the classical theory, a numerical analysis is performed to extend class E feasibility at higher frequencies. The design of hybrid class-E amplifier in LDMOS technology for UMTS base-station applications will be presented, in order to validate the theoretical results. The simulated PA reaches an output power of 40.7 dBm in correspondence of 56% drain efficiency.

Class F −1 PA: Theoretical aspects

This contribution presents an analysis of the Class F-1 power amplifier considering different waveforms as driving signals and output current, comparing the output performance for two noteworthy cases. A MMIC Class F-1 amplifier in GaAs pHEMT technology is designed in order to validate the proposed theoretical analysis. The designed amplifier shows an output power of 28.5 dBm with a peak efficiency of 54% at 9.6 GHz.

Effects of Envelope Tracking technique on an L-band power amplifier

This contribution presents the application of Envelope Tracking technique on a LDMOS 2nd harmonic tuned PA, designed to operate at 2.14 GHz. Accounting for the input dynamic signal, optimum drain and gate bias voltages are derived starting from a simplified model of the active device. Experimental results give an increase up to 40% in average efficiency, when bias tracking is applied. The application of Envelope Tracking does not impact on output power and gain performance, in the selected back-off region, implying also a reduction in the spectral regrowth when complex signals are involved.

Evaluation of FET performance and restrictions by low-frequency measurements

In this paper a characterization technique for the evaluation of transistor performance and restrictions is presented, based on a simple and low-cost measurement system. Experimental examples, carried out on a 0.5 × 1000 μm2GaN HEMT, are reported. The validity of the proposed approach is demonstrated by comparing the results with the ones obtained by means of commonly adopted measurement setups.

Development of a PWM based transmitter for P-band SAR applications

In this paper, authors present the preliminary measurements of a PWM-based transmitter. It is realised by cascading a pulse width modulator and a driver stage (PWCD), with a high efficiency Class E switched mode power amplifier (SMPA). The PWCD was realized by using 250nm BiCMOS process from IHP (SGB25V GD), while the SMPA was realized by using a packaged GaN device from UMS (CHK040A-SOA). The preliminary results showed output power levels higher than 40W with efficiency close to 70 %.

A High Power Solid State Amplifier for Galileo Satellite System Exploiting European GaN Technology

This paper describes the development of an L-Band (f 0 = 1.575 GHz) high power and efficient solid state power amplifier (SSPA) designed for the European satellite navigation system (i.e. Galileo). The amplifier, developed in the framework of the European Project named SLOGAN, exploits the GH50-10 GaN technology available at United Monolithic Semiconductor foundry. The aim of the project is to offer, using as much as possible European technologies, a valid alternative to replace traveling wave tube amplifiers with more compact and reliable systems. All the SSPA functionalities, i.e. power supply, power conditioning and radio frequency amplification, are integrated in the developed architecture and accommodated in a single box with limited volume and mass. The required output power level is achieved by parallelizing several GaN die power bars of 12 and/or 25.6 mm. In continuous wave operating mode, the overall SSPA delivers an output power higher than 250 W at less than 2 dB of gain compression in the whole E1-band. Moreover, the registered gain and efficiency are higher than 67 dB and 54%, respectively.

Theoretical consideration on harmonic manipulated amplifiers based on experimental data

This contribution aims at the experimental confirmation of the advantages of the harmonic manipulation theory, using a low-frequency low-cost characterization setup. A 0.5-μm 10×100-μm (1-mm gate periphery) GaN HEMT has been characterized synthesizing at the current-generator plane different load conditions, realizing tuned-load and Class-F operation. The measurements clearly demonstrate the importance of by synthesizing the required loads at the correct reference plane, giving an experimental proof of the performance predicted by theoretical analysis.

Design and test of a pulse-width modulator and driver for space-borne GaN switch mode power amplifiers in P-band

In this paper, the design and test of a single-chip RF pulse-width modulator and driver (PWMD) aimed at exciting a high-power class-E GaN high-power stage at 435 MHz is described. For the required buffer size, avoiding potential ringing of the pulses within the buffer structure presents a major challenge in the design process. Therefore, a smaller test chip capable of driving capacitive loads of up to 5 pF was initially designed, fabricated, and tested. An approach based on three-dimensional electromagnetic simulations was used to validate the test results and offers excellent simulation accuracy. Based on the results obtained for test chip an enlarged PWMD chip capable of driving a 40 W high-power stage has been designed and tested on passive loads representing the targeted final stage.

An efficient, linear and compact GaN-MMIC power module for microwave backhaul links

A GaN-MMIC power module for microwave back-haul applications in C-band frequency range is presented in this contribution. The design is based on a commercial 0.25 μm channel length GaN power process. The module is composed of two stages. The final stage is designed in order to reach 38 dBm of saturated output power with high efficiency and AM/AM linearity. The driver stage is integrated in order to achieve 25 dB of gain and to partially compensate the phase distortion generated by the final stage. The size of the passive matching networks is minimized, allowing to implement the overall circuit in a 3×3mm2 chip area. An uneven drain bias voltage for the two stages is adopted in order to maximize the total efficiency. The module shows 38 dBm of saturated output power, 25 dB of gain, 55% of power added efficiency and less than 1.5 degree of phase distortion at 7 GHz.

Class F-C X-band MMIC GaN power amplifier: An extension of waveform engineering approach

This contribution reports the design of an X-band MMIC power amplifier in a 0.25 um GaN technology, proposing for the first time a harmonic manipulation approach on a class C bias condition. Output network provides the power matching condition at fundamental frequency and an open circuit condition at the 3rd harmonic; the correct phase ratio between drain current components is assured by the proper input 2nd harmonic impedance. This solution allows to reach an efficiency higher than 60% in the frequency band 8.5 GHz–9.5 GHz.