Published online by Cambridge University Press: 05 March 2013
What is a tuned power amplifier?
Tuned power amplifiers are key components in the transmission path of wireless communication systems and in automotive radar. They typically deliver the power required for transmitting information to the antenna with high efficiency and, usually, high linearity, over bandwidths of 10% to 20% relative to the center frequency of the amplifier. For battery-operated applications in particular, minimum DC power consumption at a specified output power level is required.
As shown in Figure 6.1, in its idealized representation, a tuned power amplifier consists of a common-emitter or common-source (very large) transistor operating under large signal conditions with large output voltage swing. The transistor drain/collector is biased through a bias T (which presents an infinite inductor to the power supply and an infinite capacitor towards the load) and is loaded with a parallel resonant tank (formed by RL, C1, L) at the frequency of interest. For the sake of simplicity, we will assume that the transistor output capacitance, Cout = Cds + Cgd or Cbc + Ccs, is absorbed in the load capacitance C1. In a similar manner, RL includes the loss resistance of inductor L1 and capacitor C1. The circuit draws DC power from the supply to amplify the input signal power and deliver it to the load. Ideally all of the DC power and the input signal power should be converted to output signal power. In practice, at least some of the DC power is dissipated as heat.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.