Có 18+ tài liệu thuộc chủ đề "Mạch RF"
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The full definitions will be shown in Chapter 2.. Starting from a basic NPN transistor structure with a narrow base region, Figure 1.1a, the first step is to go to the model where the base emitter junction is replaced with a forward biased diode.. Figure 1.1 Low frequency ‘T’ model for a bipolar transistor. Note that considerable insight into the...
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Commonly used figures of merit include h FE , the short circuit low frequency current gain, f T , the transition frequency at which the modulus of the short circuit current gain equals one, GUM (Maximum Unilateral Gain), the gain when the device is matched at the input and the output and the internal feedback has been assumed to be...
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Using these parameters, the input and output impedances/admittances can be calculated in terms of the y parameters and arbitrary source and load admittances. Figure 3.1 y parameter representation of an amplifier. However, if y 11 is large, this part of the input impedance is lower and the device is more likely to be stable. Note that the imaginary part of...
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It will show that there are optimum coupling coefficients between the resonator and the amplifier to obtain low noise and that this optimum is dependent on the definitions of the oscillator parameters.. The effect of coupling power out of the oscillator.. Tuning effects including the varactor Q and loss resistance, and the coupling coefficient of the varactor.. These oscillator designs...
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The typical symbol for a mixer is shown in Figure 5.1.. Figure 5.1 Typical symbol for a mixer. An ideal mixer should multiply the RF and LO signals to produce the IF signal.. Most of these requirements can be met by the perfect multiplication of two signals as illustrated in equation (5.1):. Here it can be seen that the output...
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For example if high efficiency is required the output network should not match the device to the load as match causes at least 50% of the power to be lost in the active device. Note that maximum power transfer using matching causes 50% of the power to be lost in the source impedance.. Measurement of the device under the actual...
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Using the circuit shown in Figure 7.2 the following steps should be performed.. Private Sub Command2_Click() Command2.Visible = False Form1.PrintForm. Private Sub Form_Load() Timer1.Enabled = False 'INITIAL VALUES. Text4.Text = "9.6e-13". Text5.Text e-9". 'L1 series inductor Text6.Text e-12". Text7.Text e-9". 'L2 Text8.Text . Text9.Text = "1.8e9". Text10.Text e-12". Text11.Text = Text4.Text Text12.Text = Text5.Text Text13.Text = Text6.Text Text14.Text = Text7.Text...
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Scientists and mathematicians of the nineteenth century laid the foundation of telecommunication and wireless technology, which has affected all facets of modern society. Interested readers may ®nd an excellent reference on the historical developments of radio frequencies (RF) and microwaves in the IEEE Transactions on Microwave Theory and Technique (Vol. In the case of a single audio channel, the information...
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A microwave signal arriving at antenna A works as input to port 1 of the circulator. This frequency conversion facilitates ampli®cation of the signal economically. A band-pass ®lter is used at the output of the mixer to stop undesired harmonics. The size of the antenna can be smaller (3 feet or even smaller with higher- power satellites) against 8 to...
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This chapter begins with an introduction to line parameters and a distributed model of the transmission line. Solutions to the transmission line equation are then constructed in order to understand the behavior of the propagating signal. Finally, the Smith chart is introduced to facilitate graphical analysis and design of transmission line circuits.. 3.1 DISTRIBUTED CIRCUIT ANALYSIS OF TRANSMISSION LINES Any...
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Further,resonant circuits are an integral part of the frequency-selective ampli®er as well as of the oscillator designs. Since the inductive reactance is directly proportional to signal frequency,it tries to block the high-frequency contents of the signal. This frequency is called the resonant frequency of the circuit. It can be analyzed as follows.. Therefore,the transfer function of this circuit has a...
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As shown in Figure 5.1, impedance matching networks are employed at the input and the output of an ampli®er circuit. Figure 5.1 Block diagram of an ampli®er circuit.. The real part of the normalized impedance (or the normalized admittance) becomes unity at certain points on the line. Figure 5.2 Transmission line with a shunt matching element.. The imaginary part of...
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Further, it may be necessary in certain cases to keep the re¯ection coef®cient below a speci®ed value over a given frequency band. Matching bandwidth can be increased at the cost of a higher re¯ection coef®cient. Multisection binomial transformers exhibit almost ¯at re¯ection coef®cient about the center frequency and increase gradually on either side. Chebyshev transfor- mers can provide even wider...
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Z 11 Z 12 Z 21 Z 22. Similarly, with a source connected at port-2 while port-1 is open circuit, we ®nd that Z 12 V 1. Similarly, when the source is connected at port-2 and port-1 has an open circuit, we. As before, assume that the source is connected at port-1 while port-2 is open. Similarly, with a...
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Figure 8.1 A two-port network with terminations.. Transfer characteristics of the network can be formulated as follows. The frequency response of the designed circuit is shown in Figure 8.3. Figure 8.3 Frequency response of the T-section shown in Figure 8.2.. Figure 8.4 Image impedance of the constant-k ®lter of Figure 8.2 as a function of frequency.. Figure 8.5 A constant-k...
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A signal-¯ow graph is a graphical means of portraying the relationship among the variables of a set of linear algebraic equations. Associated terms are de®ned in this chapter along with the procedure to draw the signal-¯ow graph for a given set of algebraic equations. The manipula- tion of signal-¯ow graphs is summarized to ®nd the desired transfer functions.. Nodes or...
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10.1 STABILITY CONSIDERATIONS. Condition (10.1.3) can be rearranged as follows:. we ®nd that (10.1.10) is satis®ed if 1. Adding (10.1.13) and we get. From (10.1.6) and we have. Multiplying (10.1.13) and we get. Figure 10.2 A graphical representation of (10.1.7).. From (10.1.16) and we get. Figure 10.3 Input and output stability circles for Example 10.1.. 10.2 AMPLIFIER DESIGN FOR MAXIMUM...
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11.1 FEEDBACK AND BASIC CONCEPTS. Figure 11.1 A simple feedback system.. Figure 11.2 A schematic oscillator circuit.. Figure 11.3 An electrical equivalent of the schematic oscillator circuit.. Equation (11.1.10) represents the most general formulation. ®rst column will be removed from (11.1.10).. From (11.1.21) and (11.1.23),. Figure 11.4 illustrates the RF sections of these two circuits (excluding the transistor's. Figure 11.4...