China
Africa
Explore chapters and articles related to this topic
Audio amplifiers
Published in Charlie Cullen, Learn Audio Electronics with Arduino, 2020
Transistors can be unstable (and noisy) and so a better option is to combine many transistors within a single integrated circuit (IC) that provides more stable functionality. The operational amplifier is a common IC example, where the common mode rejection (CMRR) of differential amplification (between inverting and non-inverting inputs) is used to reduce the impact of noise within the circuit itself. The ideal (theoretical) characteristics of an operational amplifier are discussed, where operational amplifiers are explained as a system with source and load resistances, using voltage dividers to show why these resistances are theoretically very high and low. High gain is important for an operational amplifier, but in practice gain must be limited using negative feedback. Voltage dividers are again used to implement this negative feedback – a fundamental element of all amplification systems. An overview of DC output blocking, AC power decoupling and Zobel networks to stabilize loudspeaker output is provided, to help explain where some of the ‘extra’ components in audio circuits come from. The final project uses an LM386 operational amplifier chip to build a minimal audio amplifier. This amplifier will be used as a building block for filtering (chapter 8) and digital circuit control (chapter 9) projects in this book and can also be augmented in other ways in additional research projects of your own.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
An operational amplifier is an integrated circuit that produces an output voltage, VO, that is an amplified replica of the difference between two input voltages, as given by the equation VO=AOLV1-V2, where AOL is called the open-loop gain. The basic symbol for the operational amplifier is shown in Figure 118.1. Most operational amplifiers are of the monolithic type, and there are hundreds of different types of operational amplifiers available from dozens of different manufacturers.
CMOS Amplifiers
Published in Tertulien Ndjountche, CMOS Analog Integrated Circuits, 2017
Operational transconductance amplifiers, which are equivalent to a voltagecontrolled current source, are generally based on single-stage structures, while additional gain stages and an output buffer are required for the design of operational amplifiers operating as a voltage-controlled voltage source. A highperformance operational amplifier should provide a high input impedance, a high open-loop gain, a large CMRR, a low dc offset voltage, a low noise, and a low output impedance. Figure 5.12 shows the block diagram and symbol of a single-ended operational amplifier. The output of the differential stage is supplied to additional gain stages in order to meet the high gain requirement. A level shifter is needed whenever the dc voltage difference introduced between the input and output voltages of a stage should be canceled. An output buffer with unity gain will be necessary if the amplifier is supposed to drive a resistive load. The use of a compensation network is necessary to avoid the conditions leading to instability when the amplifier operates with a feedback.
Design of high gain and high bandwidth operational transconductance amplifier (OTA)
Published in International Journal of Electronics, 2022
Shikha Soni, Vandana Niranjan, Ashwni Kumar
Operational amplifier (Op-amp) is one of the elementary structural blocks in the domain of analog and mixed signal designs. These circuits are primarily designed with the intention of availing very low input offset, quite higher output impedance in order achiever superior isolation. Higher order output voltage gain, current and impedances are the characteristic design parameters intended for the desired application. The operational amplifier has a variety of applications while designing switched capacitor array circuitries, phase-locked loops (PLL), data converters, current biasing circuits and low-dropout regulator (LDO), etc. (Briseno Vidrios et al., 2018; Maity & Patra, 2017; Marx et al., 2018; Sarma et al., 2018; Sutula et al., 2016). Moreover, the escalating demand in today’s smart technological world with the intention of designing energy-efficient systems fetches the requirements for designing particularly low-power, high-speed and area-efficient circuitries (Siddhartha et al., 2010; Yavari & Moosazadeh, 2014,; Abdelfattah et al., 2015). The supply voltage reduction also results in the decrease in power consumption. Although reduction in supply voltage is not a superior technique since it results in degradation of the dynamic range of the designed circuitries and hence they experience the issues related to limiting slew rate and limited bandwidth.
On the Effect of Operational Amplifier Gain-bandwidth Product on the Performance of Basic Building Blocks
Published in IETE Journal of Education, 2022
The operational amplifier is a very useful integrated circuit for realizing several functions such as summation, amplification, differentiation, integration, rectification, etc. Most of the engineering curricula have a basic course on Linear integrated circuits [1–7]. Several teachers have been teaching about these for the past few decades. However, there is still is a need to pack more information to enhance the understanding of the opamp finite gain-bandwidth product (GBW) to the students. In this paper, we review certain ideas well recognized by Active Filter researchers over the years but put into practice more recently in contemporary Analog IC designs. We describe the basic circuits using the finite frequency-dependent gain model of the opamp without considering the virtual ground concept and then describe methods of reducing the deviation in performance. We also describe circuits that exploit the opamp finite GBW in realizing simpler circuits instead of considering it as an undesirable problem. All these ideas can be explained by teaching the students differently from the beginning, which is the subject matter of this paper.
Power-Aware Testing for Maximum Fault Coverage in Analog and Digital Circuits Simultaneously
Published in IETE Technical Review, 2022
Vivek Kumar Singh, Trupa Sarkar, Sambhu Nath Pradhan
The operational amplifier (Op-Amp) is the basic building block of many analog circuits. Detecting its faults is important because, in an Op-Amp-based analog circuit, the maximum possible faults are in Op-Amp. Hence Op-Amp testing is very important in the analog industry. Here a two-stage Op-Amp is designed where the first stage is a differential amplifier, and a common source amplifier is used as the second stage to increase gain. Here two types of fault models are considered: stuck short faults and stuck open faults in Figure 2(a,b). Then a low-pass filter, an inverting amplifier, a comparator and a state variable filter are designed using this Op-Amp.