Efficient Optimization Technique For Darlington Amplifier (Research Paper Sample)

Darlington Amplifier Optimization
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Table of Contents
* Introduction………………………..4
* Problem Statement…………………4
* Experimental Circuits………………..4
* Observations and Description…………...6
* Concluding Remarks…………………….7
Abstract
The devices like MOSFET, JBTs, and IJBTs are used as a single signal transmitters and receivers. In this paper, there performances are monitored against the frequency response of input signals and the variation in their voltage, current gains, and bandwidths were observed.
Darlington Amplifier Optimization
a. Introduction
The electronic components are continuing to grow in today’s globalized market, and there are continuous research and development aimed to reduce the size and costs of these components. The properties of the components need to be monitored and analyze according to various cost-effective and design mechanisms to make the system more reliable. The later developments in the field are focusing on the access of these components using wireless or remote access terminals. The new developed USB and other interfaces are the mirrors of these efforts. One of the most important processes in the electronics industry is the process of amplification. Nearly all of the electronic circuits including both digital and analogue circuits require the installation of the amplifiers in their designs to scale the signals to useful levels. The output from the electric is extremely small and needs amplification to be understood by the end users. One of the most reliable applications of the MOSFET and BJT devices are their application in the power engineering (Enslin & Hartman, 2010). These devices are used to protect the electric circuits from overloading and prevent them from the adverse effects of faulty conditions like short circuits. These devices are commonly known as circuit breakers and have wide domestic and industrial applications. The conventional circuits are attached in series to the supply, so the response time of the circuit breakers to the changes in the circuit is of extreme importance.
The circuit breakers and switches need to operate on the AC circuits rather the DC loads, the conduction properties of the designed circuit also serve as a performance parameter for the circuits. The development of the circuit breakers using the Solid State Technologies have reduced the power surges and increased the reliability of the devices to a large extent. There are many types of the power devices available in the market comprising of IGBT’s, BJTs, and MOSFETs. IGBTs have greater reliability at higher frequencies, but they require driving current (Enslin and Hartman, 2010). While on the other hand MOSFETs have become a reliable choice for many of the designers due to its low operating current but the bipolar transistor like in IGBTs might still serve as a reliable and effective device in many of the industrial and domestic applications. A proper understanding of the technological parameters and operating conditions is necessary to decide the use of the devices in the local and industrial applications.
b. Problem Statement
The MOSFETs and IGBTs are indeed the devices of choice and can be applied to the devices operations under 250V. However, their choice is mainly governed by the application of the devices, cost, size, speed, and thermal properties of the application circuit. This research is focused on the hybrid combination of the devices like IGBTs, MOSFETs, diodes, and BJTs in the circuits operating and lower frequencies like in radio and TV transmitters and receivers (Enslin, 2007). The operation of the devices is observed with the addition of the resistances making the hybrid device an effective small signal gainer circuit.
c. Experimental Circuits
The current empirical analysis was carried out by using compound units of BJT-FET and BJT-MOSFET devices in Darlington pair. The circuits are presented in the figures as Circuit-1 and circuit-2 respectively, and they are treated as reference amplifiers to be compared with the designed hybrid circuit. The hybrid circuit shown in the picture is composed of the compound assembly of MOSFET, FET and BJT in Triple Darlington circuit. Unlike the reference circuits, the designed circuit’s drains M1 and J2 are directly connected to the biasing supply VCC. The resistance RA and RAD are introduced in the circuit along with a bypass capacitor across the emitter resistance. The biasing parameters are summarized in table 1 for the respective circuits.
Figure 1: Designed Circuits (Yuan, et al., 2013).
Table 1: Design and biasing parameters (Yuan, et al., 2013).
* Observations and Description
The amplifiers gave in the circuit-1, and circuit-2 provide reliable and distortion free results in the range of 1-15 mV, while the designed circuit presented in the circuit-3 provides accurate results in the range of 1-5 mV. The performance of the circuits was observed at the input signals at one mV and1 KHz AC voltages. The variation in the maximum voltage gain as a function of frequency is presented in figure 1.
Figure 2: Voltage and current results (Yuan, et al., 2013).
The results prove that,
The maximum voltage gain for the circuit-1: 79.965.
The maximum current gain for the circuit-1: 23.925
The maximum bandwidth for the circuit-1: 749.391 KHz.
The peak output current: 7.231µA.
The peak output voltage: 72.131 mV.
Similarly, the reading for the circuit can be summarized as:
The maximum voltage gain: 115.522
The maximum current gain: 35.242
The maximum bandwidth: 22.28 KHz.
The peak output current: 10.661 µA.
The peak output voltage: 106.67 mV.
The circuit-3 produces 186.846 maximum voltage gain, 16.542 maximum current gain, 369.542 kHz maximum bandwidth, 19.279µA peak output current, and 192.768 mV maximum output voltage. From the above observations, it is clear that the bandwidth consumed by the circuit-3 lies between both reference circuits and the values for peak voltages, current, voltage and current gains have higher values compared to both of them. The observations after the addition of the resistance in the circuit are summarized as:
1. When a resistance RA is removed from the circuit; the opposite half cycles of the circuit and the values for the voltage and current gains cannot remain identical. The negative half cycles of the circuit are slightly suppressed and widen (Malik 1708).
2. It was also observed that when the drain points of the circuit-3 are detached from the Vcc and connected to node-5, the voltage gain falls to 169.241 and the bandwidth is reduced to 3.782 kHz. If the drain points of MOSFETs and JFETs are removed from the Vcc and then connected to node-5, the amplifier provides poor frequency responses.
These variations in the voltage, current gains, and bandwidth are summarized in the table-2. The voltage gain of the reference circuit-1 gradually decreases with the increase in the temperature. The bandwidth decreases to a certain value of the critical temperature. The voltage gain and bandwidth of the reference circuit-2 also increases with the increase in the temperature.
Table 2: Variations in the temperature voltage gains and bandwidth with respect to temperature (Malik, 2014).
The voltage concerning the change in the load resistance is also measured but not presented in the graphical or tabular form. It was observed that the voltage gain of the device increases to an absolute value against resistance value of RL for all three circuits and then tends to saturate itself towards a specific value. Similarly, the total harmonic values for the respective circuits were also calculated. It was observed that the amplifiers used in the circuit-1 and circuit-2 displayed the values of THD having 3.75% and 3.48% respectively. The proposed circuit-3 only depicted value of 0.71%. It was also observed that when the circuit is driven using only MOS values, ...