A Comprehensive Guide of Design of Microwave Amplifiers

A Microwave amplifier is a widely used device to amplify signals. A novice may find it difficult to pick the right Microwave Amplifier and optimize the use of the device. Understanding the design of the equipment can help to make the best use of it. The type of microwave amplifier you must pick depends on the output you need to achieve. When it comes to the performance of the device the factors you must consider are: semiconductor technology, matching networks, thermal management, circuit architecture, and design methodology, etc. The design of an amplifier meets physical, electrical, thermal, and economic requirements for a particular application and frequency range. The performance of the device in terms of frequency band, noise figure, gain, power output, linearity and input and output VSWR depends on the factors like device size, matching networks, circuit design topology, the number of gain stages, design methodology, fabrication technology, the aspect ratio for the devices between stages, and packaging. Most of the times, it involves trade-offs among size, reliability, electrical performance, and cost. The two types of microwave amplifier designed are low-noise and power amplifier. While designing an amplifier, the input is matched for minimum noise, maximum gain, or linearity and output is matched for maximum gain, optimum power or PAE/linearity. All the matching networks contain distributed and lumped elements. Let’s learn about them one by one – In a low noise amplifier the primary goal is to keep the noise figure lowest and therefore, the transistor’s input is matched for optimum noise figure. On the other hand, the output is matched to 50 Ω system impedance for maximum gain and return loss (RL). When it comes to a Power Amplifier the transistor’s input is joined and matched for gain and RL while the 50 Ω system impedance is matched to a required load at the transistor’s output to attain maximum power. Moreover, in a linear amplifier, the output and input are matched for superior linearity. The supply voltage in a microwave amplifier whether drain or collector is applied through an RF choke or biasing circuit and it is an integral part of the matching network. The power amplifiers are non-linear circuits; therefore linearization for such circuits must be achieved to minimize distortion for multiple-carrier communication applications. The design of such circuits can be obtained in several ways such as by using measured source-pull and load-pull data, accurate non-linear models, and by using some distortion cancellation technique. For detailed information about the particular microwave amplifier, you must read the description provided ON THE RADITEK web site http://www.raditek.com You can find a wide range of variants to choose from. Raditek Amplifiers are offered in Frequency bands covering 1MHz to 96GHz and Power Ranges a few mille watts to 15 Kilo watts. Raditek solid state amplifiers include either Gallium Arsenide (GaAs) or Gallium Nitrate (GaN) active devices: these are the devices that do the actual amplification. Simplistically GaAs has the best linearity and GaN the best efficiency. Applications are numerous; our focus is typically RF high power generation for RF and Microwave applications such as radio transmitters. Interstage amplifiers, medical amplifiers for cancer treatment, Low Noise amplifiers for Receivers