This part of the design has the most influence on the efficiency and output power, which is why it has the initial focus of the design effort. The most important component in a Doherty amplifier is the transistor.įor the PA performance, the output matching circuit is crucial. From their result, a separate set of requirements is produced for both amplifier paths and the impedances used throughout the design. Because the Doherty topology is more elaborate than a single PA, these calculations are also more complex. The first step of the design is entering the specifications and transistor data in a set of general system calculations. The transistor data are provided by Ampleon in the form of measurements, models and/or load-pull files. This component is selected to match the requirements with the best performance. The most important component in a Doherty amplifier is, of course, the transistor itself. When designed properly, this topology can produce a good efficiency over a wide output power range and with high linearity. It’s used to amplify the high power peaks of the input, hence the name. The peaking path is biased in class C, which means that it will only produce output power when the input signal is large enough. The carrier path is always amplifying the input signal and produces output power over a wide range of input powers. It consists of two separate paths, both of which serve a specific purpose. The Doherty topology is a very common choice for base station amplifiers. The block diagram of a Doherty amplifier. Incorporating these mechanical constraints already in the prototype design will make the integration process easier for the customer. The full set includes electrical specs like frequency range and output power but also mechanical specs like size constraints and PCB material. The specifications of the Doherty amplifier are a combination of requirements from wireless standards and Ampleon’s customers. These prototypes incorporate more broadband amplifiers, covering multiple frequency bands (eg 700-900 MHz or 1.8-2.3 GHz). For customers of Ampleon, Bruco Integrated Circuits designs so-called Doherty amplifier module prototypes, the schematic and PCB layout of which are used as a basis for base station equipment development and tests. Typically, there are multiple amplifiers, each tuned to a specific frequency band, with power, efficiency and linearity as important parameters. 5G MIMO communication to mobile devices will ride the mm-wave (27 GHz).įrom the antenna, the base stations run a wired backhaul to a receiver/amplifier subsystem that boosts the cellular signal to the mobile device and an optical fiber connection to the core network. Bundling all transmitted power to the user increases efficiency. Rather than broadcasting in all directions, beam steering technology allows the base stations to send the radio signal directly to the targets, with advanced signal processing algorithms determining the best path. To be able to send and receive more data simultaneously, and thus connect more users at the same time, 5G employs ‘massive’ MIMO (multiple input, multiple output) antennas, consisting of a very large number of antenna elements. For customers of Ampleon, Bruco Integrated Circuits designs so-called Doherty amplifier module prototypes. Higher frequencies bring higher bandwidth and speed, but lower area coverage. The high band (26-27.5 GHz) in the millimeter-wave (mm-wave) spectrum services a radius of less than one kilometer with typical speeds of 1-3 Gb/s. Together, these are called sub-6 GHz bands. In the mid-band (3.4-3.8 GHz in Europe), the tower covers a radius of four kilometers and supports 100-900 Mb/s. The low-band (600-700 MHz) base station tower has a large area coverage with a ten kilometer radius, combined with a narrow bandwidth and speeds of 30-250 Mb/s. They’ll initially operate in conjunction with existing 4G networks before evolving to fully stand-alone networks in subsequent releases and coverage expansions.ĥG applications operate in three frequency bands. The 5th generation of mobile networks has been designed to meet the steep growth in data and connectivity demand of modern society, the ever-expanding internet of things with billions of connected devices and tomorrow’s innovations. For the customers of Ampleon, Bruco Integrated Circuits develops efficient PA modules for 4G/5G base station applications in the range of 0.6-4 GHz.įeaturing lower latency, higher capacity and increased bandwidth, 5G is a significant evolution of today’s 4G LTE (Long-Term Evolution) standard. Going to higher frequencies makes the power amplifier application design even more challenging. Market demand for higher speeds and larger bandwidths drives the move from 4G to 5G.
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