RF Power Amplifier for TETRA Base Station

Lineaarisia tehovahvistimia tarvitaan järjestelmissä, joissa käytetään suureen spektritehokkuuteen pyrkiviä modulointimenetelmiä. Yksi tällaisista järjestelmistä on TETRA-järjestelmä (TErrestrial Trunked RAdio). Lineaariset tehovahvistimet ovat usein huonoja hyötysuhteeltaan. Siksi erilaisia linearisointimenetelmiä käytetään tehovahvistimien linearisointiin, jotta niiden hyötysuhdetta saadaan parannettua. Erilaisia linearisointimenetelmiä on esitelty tämän työn alkupuolella. Tämän työn tarkoituksena on tutkia LDMOS ja GaN tyyppisiä transistoreja ja niiden sopivuutta TETRA tukiaseman tehovahvistimiksi. Piirisimulaattoria apuna käyttäen LDMOS- ja GaN-transistorien tyypilliset ominaisuudet selvitetään ja annettujen vaatimusten mukaiset tehovahvistinkytkennät muodostetaan. Simulaatioista saatua tietoa hyödyntäen TETRA vahvistimen prototyyppi valmistetaan. Prototyyppivahvistin mitataan ja saatuja mittatuloksia verrataan simultaatiotuloksiin sekä TETRA-standardin asettamiin vaatimuksiin. Mittaustulosten perusteella LDMOS tyyppinen transistori on tutkituista transistoreista paras vaihtoehto TETRA-tehovahvistimeksi. Selvitys kuitenkin osoittaa, että jos GaN-transistorien hinta laskee, voivat ne tarjota varteen otettavan vaihtoehdon LDMOS-transistoreille TETRA-tukiasemakäyttöön.Linear power amplifiers are needed in systems, where spectrum efficient modulation methods are used. One of these systems is TETRA (TErrestrial Trunked RAdio). High linearity of power amplifier usually affects negatively its power efficiency. Therefore, different linearization methods are used to keep the power amplifier linear, while its efficiency is increased. Different linearization methods are presented in begining of this study. The scope of this thesis work is to study LDMOS and GaN transistor power amplifiers and select a suitable transistor to be used in the TETRA base station power amplifier. Using a circuit simulator, LDMOS and GaN transistor characteristics are analysed and power amplifier circuits are designed according the design specifications. Using the information derived from the simulations, a prototype of TETRA power amplifier is constructed. The constructed power amplifier circuit is then measured and the results are compared to simulation data and requirements of the TETRA standard. Based on the achieved measurement results, the LDMOS transistor is the most suitable choice to be used in TETRA power amplifier. However the study shows, that if the price of the GaN devices goes down, they may challenge LDMOS transistor, as they can offer wide frequency bandwidths with decent power efficiency and acceptable gain

A bipolar, semi-gaussian pulse shaping amplifier based on transconductance-C continuous time filters for use in a high resolution, small animal x-ray CT system

A new bipolar, semi-gaussian pulse shaping amplifier using transconductance-C (Gm-C) filters has been developed for use with the Oak Ridge National Laboratory (ORNL) MicroCAT small animal x-ray CT imaging system. The MicroCAT system employs Cadmium Zinc Telluride (CZT), a relatively new semiconductor detector material. The pulse shaping amplifier is based on a Gm-C filter topology and has adjustable gain, tunable filter time constants and quality factors as well as a differential signal path. The transconductor circuit design is also presented with emphasis placed upon the noise and linearity of the circuit. The architecture and experimental results for the prototype pulse shaping amplifier are also presented. The prototype was fabricated in the 1.2μ AMI NWELL CMOS process through the MOSIS program

The present situation and forecasts of semiconductor elements performance within the microwave range, 1970-1985

The present situation and possible developments over the period 1970-1985 for active semiconductor elements in the microwave range are outlined. After a short historical survey of FT techniques, the following are discussed: Generation, power amplification, amplification of small signals, frequency conversion, detection, electronic signal control and integrated microwave circuits

Amplitude and phase modulation techniques for an asymmetric multi-level outphasing transmitter

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 93-95).New techniques for improving outphasing transmitters show potential of breaking the traditional linearity-efficiency trade-off by using highly efficient non-linear switching Power Amplifiers (PAs). This work focuses on two of the main building blocks of modem outphasing systems, the power supply switching network and the phase modulator. Both are ubiquitous building blocks in modern RF transceivers, and both are especially critical in Asymmetric Multilevel Outphasing (AMO) systems. A design of the power supply network and control scheme is proposed for an implementation in mm-wave operating frequencies as part of a complete transmitter in 45nm SOI CMOS utilizing four discrete power supplies and achieving data rates of up to 4GS/s. The design includes analysis and simulation of the control signal data path requirements for optimal system operation as well as switch optimization and effects of the driving strength on overall system performance. A new design concept is proposed for a phase modulator utilizing the phase shifthing capabilities of a resonant tank and the ability to seperately control the circuit properties via its components. A prototype in 65nm CMOS achieves 12 bits of resolution, with an Effective Number Of Bits (ENOB) of 10.2 bits and very fast settling time of less than 5 carrier cycles. The chip is also tested as a stand alone transmitter showing an EVM of less than 5% for 8-PSK modulation at maximum data rate, meeting the requirements for operation at the Medical Implant Communication Services (MICS) band.by Gilad Yahalom.S.M

Design of a Power Amplifier and Envelope Amplifier for a Multi-band Multi-standard Envelope Tracking System

This thesis presents the design of a Power Amplifier (PA) and envelope amplifier for an Envelope Tracking (ET) system that is aimed at meeting emerging radio standards in terms of power efficiency and linearity. The class J mode of operation, as well as the efficiency and power contours from load pull was exploited to develop an adequate procedure for the design of a broadband and high efficiency radio frequency PA. An in-depth study has also been conducted for a hybrid envelope amplifier topology in order to optimize it for power efficiency through proper setting of its switching stage supply. Two separate proof of concept prototypes of the PA and envelop amplifier were designed, fabricated and tested. The PA designed was able to achieve an average drain efficiency of 73.6%, average output power of 45.89dBm, and an average gain of 18dB between 650MHz and 1.050GHz (48% bandwidth). The envelope amplifier achieved close to 74.6% efficiency for a 5MHz bandwidth LTE signal envelope with 6.4dB peak to average power ratio

ISM-Band Energy Harvesting Wireless Sensor Node

In recent years, the interest in remote wireless sensor networks has grown significantly, particularly with the rapid advancements in Internet of Things (IoT) technology. These networks find diverse applications, from inventory tracking to environmental monitoring. In remote areas where grid access is unavailable, wireless sensors are commonly powered by batteries, which imposes a constraint on their lifespan. However, with the emergence of wireless energy harvesting technologies, there is a transformative potential in addressing the power challenges faced by these sensors. By harnessing energy from the surrounding environment, such as solar, thermal, vibrational, or RF sources, these sensors can potentially operate autonomously for extended periods. This innovation not only enhances the sustainability of wireless sensor networks but also paves the way for a more energy-efficient and environmentally conscious approach to data collection and monitoring in various applications. This work explores the development of an RF-powered wireless sensor node in 22nm FDSOI technology working in the ISM band for energy harvesting and wireless data transmission. The sensor node encompasses power-efficient circuits, including an RF energy harvesting module equipped with a multi-stage RF Dickson rectifier, a robust power management unit, a DLL and XOR-based frequency synthesizer for RF carrier generation, and a class E power amplifier. To ensure the reliability of the WSN, a dedicated wireless RF source powers up the WSN. Additionally, the RF signal from this dedicated source serves as the reference frequency input signal for synthesizing the RF carrier for wireless data transmission, eliminating the need for an on-chip local oscillator. This approach achieves high integration and proves to be a cost-effective implementation of efficient wireless sensor nodes. The receiver and energy harvester operate at 915 MHz Frequency, while the transmitter functions at 2.45 GHz, employing On-Off Keying (OOK) for data modulation. The WSN utilizes an efficient RF rectifier design featuring a remarkable power conversion efficiency, reaching 55% at an input power of -14 dBm. Thus, the sensor node can operate effectively even with an extremely low RF input power of -25 dBm. The work demonstrates the integration of the wireless sensor node with an ultra-low-power temperature sensor, designed using 65 nm CMOS technology. This temperature sensor features an ultra-low power consumption of 60 nW and a Figure of Merit (FOM) of 0.022 [nJ.K-2]. The WSN demonstrated 55% power efficiency at a TX output power of -3.8 dBm utilizing a class E power amplifier

Large signal design of silicon field effect transistors for linear radio frequency power amplifiers

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Improving linearity utilising adaptive predistortion for power amplifiers at mm-wave frequencies

The large unlicensed 3 GHz overlapping bandwidth that is available worldwide at 60 GHz has resulted in renewed interest in 60 GHz technology. This frequency band has made it attractive for short-range gigabit wireless communication. The power amplifier (PA) directly influences the performance and quality of this entire communication chain, as it is one of the final subsystems in the transmitter. Spectral efficient modulation schemes used at 60 GHz pose challenging requirements for the linearity of the PA. To improve the linearity, several external linearisation techniques currently exist, such as feedback, feedforward, envelope elimination and restoration, linear amplification with non-linear components and predistortion. This thesis is aimed at investigating and characterising the distortion components found in PAs at mm-wave frequencies and evaluating whether an adaptive predistortion (APD) linearisation technique is suitable to reduce these distortion components. After a thorough literature study and mathematical analysis, it was found that the third-order intermodulation distortion (IMD3) components were the most severe distortion components. Predistortion was identified as the most effective linearisation technique in terms of minimising these IMD3 components and was therefore proposed in this research. It does not introduce additional complexity and can easily be integrated with the PA. Furthermore, the approach is stable and has lower power consumption when compared to the aforementioned linearisation techniques. The proposed predistortion technique was developed compositely through this research by making it a function of the PA’s output power that was measured using a power detector. A comparator was used with the detected output power and the reference voltages to control the dynamic bias circuit of the variable gain amplifier. This provided control and flexibility on when to apply the predistortion to the PA and therefore allowing the linearity of the PA to be optimised. Three-stage non-linear and linear PAs were also designed at 60 GHz and implemented to compare the performance of the APD technique and form part of the hypothesis verification process. The 130 nm silicon-germanium (SiGe) bipolar and complementary metal oxide semiconductor (BiCMOS) technology from IBM was used for the simulation of the entire APD and PA design and for the fabrication of the prototype integrated circuits (ICs). This technology has the advantage of integrating the high performance, low power intensive SiGe heterojunction bipolar transistors (HBTs) with the CMOS technology. The SiGe HBTs have a high cut-off frequency (fT > 200 GHz), which is ideal for mm-wave PA applications and the CMOS components were integrated in the control logic of the digital circuitry. The simulations and IC layout were accomplished with Cadence Virtuoso. The implemented IC occupies an area of 1.8 mm by 2.0 mm. The non-linear PA achieves a Psat of 11.97 dBm and an IP1dB of -10 dBm. With the APD technique applied, the linearity of the PA is significantly improved with an IP1dB of -6 dBm and an optimum IMD3 reduction of 10 dB. Based on the findings and results of the applied APD technique, APD reduced intermodulation distortion (especially the IMD3) and is thus suitable to improve the linearity of PAs at mm-wave frequencies. To the knowledge of this author, no APD technique has been applied for PAs at 60 GHz, therefore the contribution of this research will assist future PA designers to characterise and optimise the reduction of the IMD3 components. This will result in improved linear output power from the PA and the use of complex modulation schemes at 60 GHz.Thesis (PhD)--University of Pretoria, 2014.Electrical, Electronic and Computer EngineeringPh