Niccolò Giovannelli

A 240-W dual-band 870 and 2140 MHz envelope tracking GaN PA designed by a probability distribution conscious approach

In this paper, we present the design of a dual-band power amplifier (PA) for envelope tracking (ET) operation. The design was based on a multi-section transmission line matching technique and has taken into account the actual probability distribution function of the WCDMA 3GPP DL signal. The technique was applied to a concurrent 870 and 2140 MHz ET PA designed around a GaN HEMT. The ET friendly design method has proven capable to meet the performance equal to those of each single band pulsed load pull with minor loss, over a bandwidth of 100 MHz, reporting an average drain efficiency of 69.5% and 51.0%, and peak power levels of 54.86 dBm and 53.96 dBm at the design frequencies. A detailed discussion of the design method and validating experimental results data are reported.

Efficiency and linearity enhancements with envelope shaping control in wideband envelope tracking GaAs PA

In this paper we present the efficiency and linearity trade-off of a dual band power amplifier (PA) for envelope tracking (ET) operation. The paper discusses the impact of envelope shaping i.e. the mapping of the drain modulated waveform to the RF output power, on system linearity and efficiency performance, for a given signal statistic. The technique was applied to a dual-band ET PA designed around a GaAs HEMT at 940 and 1940 MHz. Analytical treatment of the design technique along with characterization at device and system level are also presented in the paper.

A 80 W broadband GaN HEMT envelope tracking PA harmonically tuned for WCDMA and LTE with 50% average efficiency

We discuss the development of a balanced GaN ET PA with optimised peak power and efficiency over 720 MHz to 960 MHz. The design was enabled by a wideband second harmonic control. The PA achieved performance delivers greater than 60% average efficiency across band at 80 W average power supporting multi-standard operation with both 2 channel WCDMA and 10 MHz LTE signals. The overall system efficiency including the ET modulator is 50% or greater with a target −50 dBc ACR across the entire bandwidth.

A 250W LDMOS Doherty PA with 31% of fractional bandwidth for DVB-T applications

We discuss the development of a wideband LDMOS Doherty PA (DPA) with optimized peak power and efficiency over 550 MHz to 770 MHz of bandwidth. The design was enabled by a wideband output combiner which involves multisection impedance transformation. The DPA delivers more than 46% average efficiency across the band at 48 dBm average power supporting DVB-T signal with 8 MHz bandwidth and PAPR of 10.5 dB. The DPA prototype achieves the target ACPR of - 50 dBc at the upper limit of the bandwidth if digital predistortion is applied.

Bi-dimensional shaping function in concurrent dual band GaAs envelope tracking power amplifier

This work reports for the first time the characterization and the bi-dimensional shaping function for a dual-band 10W ET-PA operating in concurrent mode at 870 and 1950 MHz. The characterization involved WCDMA 6.5 PAR excitation, and a detailed analysis of the signals statistic resulting from the ET mode is reported as well. The measured data reported an average DE for the concurrent modes of 49.2 %, while we observed a significant variation of the PAR, with respect to single band operation. We demonstrate that this PAR variation is due to the specific gain versus power level shape, which is established during the concurrent ET-PA operation.

A concurrent dual band 870 and 1970 MHz 10 W envelope tracking PA designed by a WCDMA probability distribution conscious approach

In this paper we propose a novel approach for the design of a concurrent dual-band power amplifier (PA) optimized for envelope tracking (ET) operation. The design was based around the WCDMA probability distribution function and implemented through a multi-section transmission line matching technique. This technique was applied to a concurrent 870 and 1970 MHz ET PA designed around a GaAs HEMT. The ET friendly design method has proven capable to enhance the average efficiency by a 2.2 factor over a signal bandwidth of 140MHz and 60MHz in the two carrier frequency bands respectively for the specific WCDMA signal. A detailed discussion of the design method and the validating experimental results are reported.

Compact Concurrent Dual-Band Power Amplifier for 1.9GHz WCDMA and 3.5GHz OFDM Wireless Systems

The aim of this paper is to focus on the dual band power amplifier design and characterization as an enabling technology for beyond 3G wireless systems. The design approach within a full characterization of the dual band power amplifier is given in the paper. For 1.98 GHz 3 GPP UL WCDMA and 3.42 GHz 5 MHz 16QAM WiMAX digital systems, the dual-band concurrent exhibited simultaneous peak power levels of 24 dBm and 17 dBm respectively, to maintain ACPR and EVM within the regulatory requirements. A performance discussion is then outlined with respect to multi band multi module PA architectures for software defined radio wireless transmitters.

Frequency Analysis and Multiline Implementation of Compensated Impedance Inverter for Wideband Doherty High-Power Amplifier Design

In this paper, we present a frequency analysis of a compensated impedance inverter and its effective implementation in the context of high-power Doherty amplifier (DPA) design. On the basis of an idealized DPA model, we calculate the expected operative bandwidth and the corresponding maximum drain efficiency as a function of the modulated signal statistics. In addition, we introduce an effective technique for the implementation of the compensated impedance inverter, suitable for preserving its broadband characteristics in the presence of large devices output capacitance. The implementation technique is based on the generalized equivalent transmission-line equivalence principle, which considers both shortening and lengthening the equivalent transmission lines. We demonstrate that, by the proposed approach, parasitic absorption is possible maintaining a low Q-factor of the equivalent network. The technique is validated by the development of a silicon laterally diffused metal-oxide-semiconductor DPA with optimized peak power and efficiency for applications in the 650-950-MHz band. The fabricated prototype is characterized by an LTE signal with a 20-MHz bandwidth and peak-to-average-power ratio of 7.5 dB and features an average drain efficiency between 37% and 47%, with an average power of 49 dBm across 37.5% of the bandwidth.

A 300 W Si-LDMOS Doherty PA for 700–950 MHz LTE applications based on a compensated output network design

In this paper we present a novel approach to the design of output combiners for Doherty PA (DPA). It is based on the compensated transmission line equivalence principle, applied to both the impedance inverter and the peak amplifier matching network considered as a whole. This technique is applied to the design of a Silicon Laterally Diffused MOS (LDMOS) DPA with optimized peak power and efficiency for LTE application in the 700 MHz to 950 MHz bandwidth. The approach permits the wideband absorption of the main and peak devices capacitance and the package parasitics. The fabricated prototype is characterized by a LTE signal with 20 MHz bandwidth and Peak to Average Power Ratio (PAPR) of 7.5 dB and features an average drain efficiency between 37 and 46%, with average power of 49 dBm across the band.

A 280 W LDMOS broadband Doherty PA with 52% of fractional bandwidth based on a multi-line impedance inverter for DVB-T applications

We introduce a new technique for the design of an output combiner for Doherty power amplifier (DPA) and its effective exploitation for the development of a wideband laterally diffused metal oxide semiconductor (LDMOS) DPA. The design is enabled by a two-line impedance inverter for the DPA back-off operation, which is capable of 52% of fractional bandwidth. The technique is validated by the development of a DPA prototype for Ultra high frequency terrestrial digital video broadcast (DVB-T) applications, with optimized peak power and efficiency over 470–806 MHz. The prototype delivers between 40 and 53% of average efficiency across the band, at 49 dBm output power in average across the bandwidth, and supporting DVB-T signals with 8 MHz bandwidth and a peak-to-average power ratio of 10.5 dB. It achieves the target adjacent channel power ratio of −52 dBc at 750 MHz if digital pre-distortion is applied, and provides 47.8 dBm of output power with a drain efficiency of 44.3%. (Less)