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Continuous-Time Circuits
Published in Tertulien Ndjountche, CMOS Analog Integrated Circuits, 2017
A class A tuned amplifier, as shown in Figure 7.17(a), is often used in applications where a narrow band of frequencies around a center frequency is of interest. The small-signal equivalent model is depicted in Figure 7.18(a). It is assumed that R0 and C0 denote the total resistance and capacitance at the output node, respectively. Applying Kirchhoff’s current law at the output node gives () (V0−Vi)sCgd+gmVi+V0(G0+sC0+1/sL)=0,
Multistage and Feedback Amplifiers
Published in Nassir H. Sabah, Electronics, 2017
In a tuned amplifier, tuned circuits are connected at the input and output of transistor amplifier stages. To increase the bandwidth, the circuits can be stagger tuned, or magnetically coupled. The maximum gain–bandwidth product in a tuned amplifier is that of the transistor.
Dielectric and thermodynamic studies of n-cyano-biphenyl (nCB) liquid crystals at microwave frequency
Published in Liquid Crystals, 2023
The underlying idea behind the perturbation technique is that the presence of a ‘small’ size dielectric sample inside a resonant cavity causes the shift in the resonant frequency and the cavity’s quality factor falls. Here, ‘small’ means the sample’s volume is considerably smaller than the cavity’s size. The observed changes in frequency and the quality factor of the cavity are used to calculate the complex permittivity of the material under test. Figure 1 is the block diagram of the experimental setup of microwave cavity spectrometer. In this setup, a signal frequency, near cavity resonance, is generated by a reflex klystron by mechanical tuning and setting of voltage. An oscilloscope sends saw-tooth ramp voltage, and a chopper signal of 31 kHz is impressed on the klystron repeller to produce an AC signal of the desired frequency. This chopper signal enables the tuned amplifier to detect the signal by the RF detector. The second derivative of the signal is fed to one channel of the oscilloscope. A signal from the Klystron was sent to the marker mixture along with harmonics of the frequency standard. The two signals are compared by a tuned radio receiver, and the two markers were generated and displayed on the second channel of the oscilloscope. A permanent record of the signal and two markers is taken on dual pen chart recorder. The separation of these markers is set to 4 MHz (Figure 2).