![]() If P 1 is the input power, P 2 is the output (load) power, R 1 is the input resistance, and R 2 is the load resistance, then P 1 = 0. Voltage-current relationships for a four-terminal network. To do so, consider the network is shown in Figure.(1). If P 2 = 2 P 1, the gain is (3)Įquations.(3) and (4) show another reason why logarithms are greatly used: The logarithm of the reciprocal of a quantity is simply negative the logarithm of that quantity.Īlternatively, the gain G can be expressed in terms of voltage or current ratio. When P 1 = P 2, there is no change in power and the gain is 0 dB. The decibel (dB) provides us with a unit of less magnitude. Historically, the bel is used to measure the ratio of two levels of power or power gain G that is, (1) In communications systems, the gain is measured in bels. Since Bode plots are based on logarithms, it is important that we keep the following properties of logarithms in mind: Read also : capacitor voltage current capacitance The Decibel Scale It is not always easy to get a quick plot of the magnitude and phase of the transfer function as we did above.Ī more systematic way of obtaining the frequency response is to use Bode plots.īefore we begin to construct Bode plots, we should take care of two important issues: the use of logarithms and decibels in expressing gain. The decibel scale will be the basic thing before we learn about ‘Bode Plot’.
0 Comments
Leave a Reply. |