A 76-84 GHz SiGe power amplifier array employing low-loss four-way differential combining transformer

This paper presents holistic design of a novel four-way differential power-combining transformer for use in millimeter-wave power-amplifier (PA). The combiner with an inner radius of 25 µm exhibits a record low insertion loss of 1.25 dB at 83.5 GHz. It is designed to simultaneously act as a balanced-to-unbalanced converter, removing the need for additional BALUNs typically required in differential circuits. A complete circuit comprised of a power splitter, two-stage differential cascode PA array, a power combiner as well as input and output matching elements was designed and realized in SiGe technology with f/f 170/250 GHz. Measured small-signal gain of at least 16.8 dB was obtained from 76.4 to 85.3 GHz with a peak 19.5 dB at 83 GHz. The prototype delivered 12.5 dBm output referred 1 dB compression point and 14 dBm saturated output power when operated from a 3.2 V dc supply voltage at 78 GHz.

Amplitude-modulation characteristics of power-combining Class-E amplifier with finite choke

Power back-off performances of a new variant power-combining Class-E amplifier under different amplitude-modulation schemes such as continuous wave (CW), envelope elimination and restoration (EER), envelope tracking (ET) and outphasing are for the first time investigated in this study. Finite DC-feed inductances rather than massive RF chokes as used in the classic single-ended Class-E power amplifier (PA) resulted from the approximate yet effective frequency-domain circuit analysis provide the wherewithal to increase modulation bandwidth up to 80% higher than the classic single-ended Class-E PA. This increased modulation bandwidth is required for the linearity improvement in the EER/ET transmitters. The modified output load network of the power-combining Class-E amplifier adopting three-harmonic terminations technique relaxes the design specifications for the additional filtering block typically required at the output stage of the transmitter chain. Qualitative agreements between simulation and measurement results for all four schemes were achieved where the ET technique was proven superior to the other schemes. When the PA is used within the ET scheme, an increase of average drain efficiency of as high as 40% with respect to the CW excitation was obtained for a multi-carrier input signal with 12 dB peak-to-average power ratio. © 2011 The Institution of Engineering and Technology.

Enhanced efficiency of envelope-tracking based broadband inverse class-E power amplifier

In this paper, the envelope-tracking technique is exploited to boost average efficiency of the newly introduced broadband Inverse Class-E power amplifier. A 2.26 GHz - 20.5 dBm - 3 V power amplifier was designed, constructed, and measured. For a multi-carrier input signal with 10 dB peak-to-average ratio, the average PAE was increased from 5.7% to 54.5%. © 2008 IEEE.

2.4 GHz high-efficiency power-combining Class-E amplifier with transmission-line harmonic traps

Experimental assessments of the modified power-combining Class-E amplifier are described. The technique used to combine the output of individual power amplifiers (PAs) into an unbalanced load without the need for bulky transformers permits the use of small RF chokes useful for the deployment in the EER transmitter. The modified output load network of the PA results in excellent 50 dBc and 46 dBc second and third-harmonic suppressions, dispensing the need for additional lossy filtering block. Operating from a 3.2 V dc supply voltage, the PA exhibits 64% drain efficiency at 24 dBm output power. Over a wide bandwidth of 350 MHz, drain efficiency of better than 60% at output power higher than 22 dBm were achieved. © 2010 IEICE Institute of Electronics Informati.

Design technique for mm-wave IC realization of the load network of switched-mode class-EF power amplifier

Analysis and synthesis of the new Class-EF power amplifier (PA) are presented in this paper. The proposed circuit offers means to alleviate some of the major issues faced by existing Class-EF and Class-EF PAs, such as (1) substantial power losses due to parasitic resistance of the large inductor in the Class-EF load network, (2) unpredictable behaviour of practical lumped inductors and capacitors at harmonic frequencies, and (3) deviation from ideal Class-EF operation mode due to detrimental effects of device output inductance at high frequencies. The transmission-line load network of the Class-EF PA topology elaborated in this paper simultaneously satisfies the Class-EF optimum impedance requirements at fundamental frequency, second, and third harmonics as well as simultaneously providing matching to the circuit optimum load resistance for any prescribed system load resistance. Furthermore, an elegant solution using an open and short-circuit stub arrangement is suggested to overcome the problem encountered in the mm-wave IC realizations of the Class-EF PA load network due to lossy quarter-wave line. © 2010 IEICE Institute of Electronics Informati.

Power back-off behaviour of high-efficiency power-combining Class-E amplifier

Power back-off performances of the modified power-combining Class-E amplifier under different amplitudemodulation schemes such as envelope elimination and restoration (EER) and envelope tracking (ET) are experimentally assessed in this paper. The modified output load network adopting three-harmonic terminations technique eliminates the need for additional lossy filtering section in the transmitter chain. Small dc-feed inductances rather than massive RF chokes as in the classic Class-E amplifier are used so as to increase the modulation bandwidth and therefore improve the linearity of the EER transmitter. High efficiency over a wide dynamic range using amplitude modulation through drain-voltage control (EER) was achieved and this agrees well with the Class-E theoretical prediction. When the PA was used within the ET scheme, an increase of average drain efficiency of as high as 40% with respect to the CW excitation was obtained for a multi-carrier input signal with 12dB peak-to-average power ratio. © 2011 Institut fur Mikrowellen.

A 75-81 GHz, 14.3 dBm Peak Output Power, 21 dB Peak Gain, SiGe Power-Combining Amplifier Operating from a Single 3.3 V Supply

A compact differential 4-way power combiner with 2.3 dB loss and high common-mode rejection characteristic for use in mm-wave PAs is presented. A complete circuit comprised of a power splitter, two-stage cascode PA array, and a power combiner was implemented in SiGe technology. Measured small-signal gain of at least 17 dB was obtained from 74.5 GHz to 80.5 GHz with a peak 21 dB at 79 GHz. The prototype delivered 13.2 dBm P1dB and 14.3 dBm Psat when operated from a single 3.3 V supply at 75 GHz.

A SiGe Power Amplifier with Integrated BALUNs for 81-86 GHz E-Band Backhaul Applications

The design of a two-stage differential cascode power amplifier (PA) for 81-86 GHz E-band applications is presented. The PA was realised in SiGe technology with fT/fmax 170/250 GHz. A broadband transformer with efficiency higher than 79.4% from 71 GHz to 96 GHz is used as a BALUN. The PA delivers a 4.5 dBm saturated output power and exhibits a 13.4 dB gain at 83.6 GHz. The input and output return losses agree well with the design specifications.

D3.1 Benefits Analysis of the Initial Operational Cruiser-Feeder Concept

The REsearch on a CRuiser Enabled Air Transport Environment (RECREATE) project is considers the introduction and airworthiness of cruiser-feeder operations for civil aircraft. Cruiser-feeder operations are investigated as a promising pioneering idea for the air transport of the future. The soundness of the concept of cruiser-feeder operations for civil aircraft can be understood, taking air-to-air refueling operations as an example. For this example, a comprehensive estimate of the benefits can be made, which shows a fuel burn reduction potential and a CO2 emission reduction of 31% for a typical 6000 nautical miles flight with a payload of 250 passengers. This reduction potential is known to be large by any standard. The top level objective of the RECREATE project is to demonstrate on a preliminary design level that cruiser-feeder operations (as a concept to reduce fuel burn and CO2 emission levels) can be shown to comply with the airworthiness requirements for civil aircraft. The underlying Scientific and Technological (S&T) objectives are to determine and study airworthy operational concepts for cruiser-feeder operations, and to derive and quantify benefits in terms of CO2 emission reduction but also other benefits.

Work Package (WP) 3 has the objective to substantiate the assumed benefits of the cruiser/feeder operations through refined analysis and simulation. In this report, initial benefits evaluation of the initial RECREATE cruiser/feeder concepts is presented. The benefits analysis is conducted in delta mode, i.e. comparison is made with a baseline system. Since comparing different aircraft and air transport systems is never a trivial task, appropriate measures and metrics are defined and selected first. Non-dimensional parameters are defined and values for the baseline system derived.

The impact of cruiser/feeder operations such as air-to-air refueling are studied with respect to fuel-burn (or carbon-dioxide), noise and congestion. For this purpose, traffic simulations have been conducted.
Cruiser/feeder operations will have an impact on dispatch reliability as well. An initial assessment of the effect on dispatch reliability has been made and is reported.

Finally, a considerable effort has been made to create the infrastructure for economic delta analysis of the cruiser/feeder concept of operation. First results of the cost analysis have been obtained.

D1.2 Operational Cruiser-Feeder Concept

The project REsearch on a CRuiser Enabled Air Transport Environment (RECREATE) is about the introduction and airworthiness of cruiser-feeder operations for civil aircraft. Cruiser-feeder operations are investigated as a promising pioneering idea for the air transport of the future.
The top level objective of the project is to demonstrate on a preliminary design level that cruiser-feeder operations (as a concept to reduce fuel burn and CO2 emission levels) can be shown to comply with the airworthiness requirements for civil aircraft. The project is funded through the Seventh Framework Programme of the European Commission. Work Package (WP) 1 has the objective to substantiate that viable and acceptable concepts for cruiser/feeder operations exist. In this deliverable the initial operational concept of the RECREATE cruiser/feeder is presented.

Full duplex reflection amplifier tag

The authors describe a reflection amplifier adapted to have both a reflection and a transmission port. The amplifier uses a single silicon bipolar transistor and demonstrates a reflection gain of 13 dB, transmission gain of 10 dB and 3.4 dB noise figure at 5.25 GHz. The added feature of transmission gain in the reflection amplifier permits practical implementation of full duplex microwave radiofrequency indentification (RFID) tag operation. By using a simple subcarrier modulation scheme full duplex RFID operation utilising this amplifier is demonstrated. These results indicate that for 27 dBm (0.5 W) effective isotropic radiated power (EIRP) transmit power it should be possible to obtain approximately 8 m downlink range and 25 m uplink range

A 2.2 GHz High-Efficiency Third-Harmonic-Peaking Class-EF Power Amplifier

This paper presents the design and implementation of a low-voltage-stress Class-EF power amplifier (PA) with extended maximum operating frequency, named as ‘third-harmonic-peaking Class-EF PA’. A novel transmission-line load network is proposed to meet the Class-EF impedance requirements at the fundamental, all even harmonics, and third harmonic components. It also provides an impedance matching to a 50 Ω load. A more effective λ/8 open- and shorted-stub network is deployed at the drain of the transistor replacing the traditional λ/4 transmission line. Implemented using GaN HEMTs, the PA delivered 39.2 dBm output power with 80.5% drain efficiency and 71% PAE at 2.22 GHz.

E-Band Transformer-Based Differential 4-Way Power-Combining Amplifier

This paper presents the design and implementation of a differential 4-way power-combining amplifier operating at E-band. The proposed 4-way power combiner (4WPC) facilitates short interconnects to the PA cells, thereby resulting in reduced loss. Simple C-L-C and L-C networks are deployed in order to compensate inductive loading due to the routing lines that would otherwise introduce mismatch and subsequently increase overall loss. Realized in SiGe technology, the PA prototype delivered 13.2 dBm output-referred 1-dB compression point and 14.3 dBm saturated output power when operated from a single 3.3 V DC supply at 75 GHz.