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Basic transistor circuits
Published in David Crecraft, David Gorham, electronics, 2018
4. A simple npn common-emitter amplifier has its base biased by current through a resistor connected to the positive supply. An alternative, to avoid dependence of the operating point on the d.c. value of the current gain β (hfe), is a potential divider to set the base voltage. An emitter resistor then determines the emitter and collector currents. The input signal is fed in via a coupling capacitor to the base. The output signal is developed across a resistor connected to the positive supply, and is fed out via a coupling capacitor from the collector. The voltage gain of a common-emitter amplifier is A = –gmR′L, where R′L is the effective load resistance.
Transistors
Published in John Okyere Attia, Circuits and Electronics, 2017
For the common-emitter amplifier, shown in Figure 7.28, the coupling capacitor, CC1, couples the voltage source, VS, to the bias network. Coupling capacitor, CC2, connects the collector resistance, RC, to the load RL. The bypass capacitance, CE, is used to increase the midband gain, since it effectively short circuits the emitter resistance RE at midband frequencies. The resistance RE is needed for bias stability. The external capacitors CC1, CC2, CE influence the low frequency response of the common-emitter amplifier. The internal capacitances of the transistor control the high frequency cut-off. The overall gain of the common-emitter amplifier can be written as A(s)=Ams2(s+wz)(s+wL1)(s+wL2)(s+wL3)(1+s/wH)
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Thus, FETs have the disadvantage of a much lower transfer conductance and therefore lower voltage gain than BJTs operating under similar quiescent current levels, but they do have the major advantage of a much higher input impedance and a much lower input current. In the case of a JFET the input signal is applied to the reverse-biased gate-to-channel PN junction and thus sees very high impedance. In the case of a common-emitter BJT amplifier the input signal is applied to the forward-biased baseemitter junction and the input impedance is given approximately by rIN=rBE≅1.5⋅β⋅VT/IC If IC=5mA and β=200, for example, then rIN≅1500Ω. This moderate input resistance value of 1.5kΩ is certainly no problem if the signal source resistance is less than around 100Ω. However, if the source resistance is above 1kΩ, then there will be a substantial signal loss in the coupling of the signal from the signal source to the base of the transistor. If the source resistance is in the range of above 100kΩ, and certainly if it is above 1MΩ, there will be severe signal attenuation due to the BJT input impedance, and a FET amplifier will probably offer a greater overall voltage gain. Indeed, when high impedance signal sources are encountered, a multistage amplifier with a FET input stage, followed by cascaded BJT stages is often used.
Isolated Interleaved Boost Converter Based Single-Phase Grid-Interfaced Photovoltaic System
Published in Electric Power Components and Systems, 2023
Pemendra Kumar Pardhi, Shailendra Kumar Sharma
This research work presents an IIBC employed with SPGIPS to minimize ripples in PV panel voltage and current and therefore improves extraction of maximum power from PV panels. The IIBC employs two insulated gate bipolar junction transistors (IGBTs) switches with sharing common emitter and two inductors, and it operates above 50% of duty ratio. During the overlapping period of both switches, inductors store the PV energy. The salient features of the employed IIBC are as follows: Facilitates less voltage stresses on windings of HFT and on power switches.Presence of the two input inductors reduces the input current ripple of the PV panel. Therefore, it improves the MPPO efficiency and reduces the energy buffer capacitor at the PV panel terminals.IGBTs shared common emitter with PV panels ground. It reduces the complexity of the gate driver circuit and also mitigates electromagnetic interference problems.It mitigates the appearance of leakage current in SPGIPS.
Current-Reuse Active Inductor-Based VCO for Reconfigurable RF Front-End
Published in IETE Journal of Research, 2022
Lakshmi Nediyara Suresh, Bhaskar Manickam
The inductive behavior is shown in the frequency range 1/R(Cgs1 + Cgs2) ≤ ɷ ≤ (gm1 + gm2)/(Cgs1 + Cgs2). The Smith chart given in Figure 5(a) shows the simulated S11 parameter of the active inductor. The designed active inductor is found to be inductive (positive imaginary part of input impedance) from 100 MHz to 3 GHz. Quality factor of the simulated active inductor is shown in Figure 5(b). The proposed design attains a maximum Q of 400 at 2.5 GHz. The expression for calculating Q of the active inductor is given by the following equation: Table 1 shows the performance comparison of the proposed CRAI with a tunable active inductor designed for multi-band operations 9 and an active inductor design using a single transistor (common emitter transistor) as the gain stage [25] to realize the active inductor. Compared to the state-of-the-art designs, CRAI consumes less power and provides a wide inductive frequency range. A compensating network is added to the single gain stage [25] to compensate for the resistive losses of the active inductor and hence a high Q is obtained. Q of the proposed active inductor is higher than [9] without adding any compensating network.
Design and Analysis of 30 GHz CMOS Low-Noise Amplifier for 5G Communication Applications
Published in IETE Journal of Research, 2023
K. Dineshkumar, Gnanou Florence Sudha
In [19], the LNA schematic of a three-stage, the single-ended cascode design is implemented for 75–91 GHz. To achieve high gain, good isolation, robustness, and variation in the model, the cascode topology is proposed in that design. This design is implemented in the 0.65 µm CMOS technology with a gain and noise figure (NF) that measures 15 and 6.4 dB, respectively. An LNA with a two-stage single-ended design was presented in [20], in which a common-base amplifier is the first stage and a common-emitter cascode amplifier is the second stage. The design amplifies the signal with a gain of 8 dB and NF is < 5 dB. The LNA with improved gm linearization is designed in [21] and an LNA design with wideband input matching and noise cancellation is presented in [22,23]. A wideband cascaded LNA [24] is designed for the 3 dB bandwidth that provides a gain of 10.7 dB and a noise figure of 4.5–5.6 dB for 29 GHz. In [25], a multiband and multi-tunable cascode LNA for 28 GHz is designed that attains a gain of 17.4 dB with a noise figure of 4 dB. An ultra-wideband LNA is presented [26] in the 45 nm technology for 24-44 GHz which has a gain of 20 dB and a noise figure of 4.7 dB. A three-stage multi-band LNA is designed in [27] with a noise figure of 4 dB and a gain of 23 dB at the 28–38 GHz frequency range. A multi-band low-noise amplifier [28] is designed for 5G communication that employs a single-input wideband matching circuit providing a noise figure of 3.8 to 4.9 dB and a gain of 8.5–12.5 dB in 0.316 mm2 area. A two-stage low-noise amplifier, which comprises common-gate and common-drain stages, has been designed in a 45 nm CMOS process that achieves a gain of 15.7 dB and a noise figure of 3.2 dB at a 28 GHz frequency range [29].