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RF và mạch lạc lò vi sóng P7

TWO-PORT NETWORKS Electronic circuits are frequently needed for processing a given electrical signal to extract the desired information or characteristics. This includes boosting the strength of a weak signal or ®ltering out certain frequency bands and so forth. Most of these circuits can be modeled as a black box that contains a linear network comprising resistors, inductors, capacitors, and dependent sources. Thus, it may include electronic devices but not the independent sources. Further, it has four terminals, two for input and the other two for output of the signal | Radio-Frequency and Microwave Communication Circuits Analysis and Design Devendrá K. Misra Copyright 2001 John Wiley Sons Inc. ISBNs 0-471-41253-8 Hardback 0-471-22435-9 Electronic 7 TWO-PORT NETWORKS Electronic circuits are frequently needed for processing a given electrical signal to extract the desired information or characteristics. This includes boosting the strength of a weak signal or filtering out certain frequency bands and so forth. Most of these circuits can be modeled as a black box that contains a linear network comprising resistors inductors capacitors and dependent sources. Thus it may include electronic devices but not the independent sources. Further it has four terminals two for input and the other two for output of the signal. There may be a few more terminals to supply the bias voltage for electronic devices. However these bias conditions are embedded in equivalent dependent sources. Hence a large class of electronic circuits can be modeled as two-port networks. Parameters of the two-port completely describe its behavior in terms of voltage and current at each port. These parameters simplify the description of its operation when the two-port network is connected into a larger system. Figure 7.1 shows a two-port network along with appropriate voltages and currents at its terminals. Sometimes port-1 is called the input while port-2 is the output port. The upper terminal is customarily assumed to be positive with respect to the lower one on either side. Further currents enter the positive terminals at each port. Since Figure 7.1 Two-port network. 243 244 TWO-PORT NETWORKS the linear network does not contain independent sources the same currents leave respective negative terminals. There are several ways to characterize this network. Some of these parameters and relations among them are presented in this chapter including impedance parameters admittance parameters hybrid parameters and transmission parameters. Scattering parameters are introduced .