China
Africa
Explore chapters and articles related to this topic
Macromodeling and Synthesis of Analog Circuits
Published in Suman Lata Tripathi, Sobhit Saxena, Sushanta Kumar Mohapatra, Advanced VLSI Design and Testability Issues, 2020
B. S. Patro, Sushanta Kumar Mandal
Some good symbolic analyzers are reported in Kolka, Biolek, and Biolkova (2008); McConaghy and Gielen (2009); Gielen and Sansen (2012); Rutenbar, Gielen, and Roychowdhury (2007); and Shi and Tan (2000). In these analyzers, the modified nodal analysis (MNA) method was principally used to formulate the system of equations. In Vazzana, Grasso, and Pennisi (2017), the importance and usefulness of MNA can be easily observed from its implemented tool using matrix laboratory (MATLAB). Then, the recursive determinant expansion techniques provide the performance of these generated symbolic models. Other methods such as dead rows and V/I methods were also reported (Fakhfakh, Tlelo-Cuautle, and Fernández 2012). These methods remove the redundancy and hence complication of the circuits to some extent. Some other methods such as nodal admittance matrix (NAM) (Sánchez-López, Cante-Michcol, et al. 2013; Sánchez-López, Ochoa-Montiel, et al. 2013) are also used for such type of reduction mechanism for the circuits. Similarly, pathological equivalents have been used instead of active devices for synthesis purposes (Tlelo-Cuautle, Sánchez-López, and Moro-Frías 2010; Saad and Soliman 2010). Binary decision diagram (Shi 2013; Zhang and Shi 2011) was earlier used for logic synthesis and verification. But afterward, this method is used more frequently for symbolic model generation and synthesis of analog circuits. This method not only removes the data redundancy but also provides a mechanism for explicit enumeration, which decreases the complexity to a certain extent.
1
Published in Richard C. Dorf, Circuits, Signals, and Speech and Image Processing, 2018
J. Gregory Rollins, Sina Balkir, Peter Bendix
DC analysis calculates the state of a circuit with fixed (non-time varying) inputs after an infinite period of time. DC analysis is useful to determine the operating point (Q-point) of a circuit, power consumption, regulation and output voltage of power supplies, transfer functions, noise margin and fan-out in logic gates, and many other types of analysis. In addition dc analysis is used to find the starting point for ac and transient analysis. To perform the analysis the simulator performs the following steps: All capacitors are removed from the circuit (replaced with opens).All inductors are replaced with shorts.Modified nodal analysis is used to construct the nonlinear circuit equations. This results in one equation for each circuit node plus one equation for each voltage source. Modified nodal analysis is used rather than standard nodal analysis because an ideal voltage source or inductance cannot be represented using normal nodal analysis. To represent the voltage sources, loop equations (one for each voltage source or inductor), are included as well as the standard node equations. The node voltages and voltage source currents then represent the quantities which are solved for. These form a vector x. The circuit equations can also be represented as a vector F(x) = 0.Because the equations are nonlinear, Newton’s method (or a variant thereof) is then used to solve the equations.
CIRCUIT FORMULATION AND COMPUTER SIMULATION
Published in Wenquan Sui, Time-Domain Computer Analysis of Nonlinear Hybrid Systems, 2018
circuit behavior, and most of the time it is computationally more expensive compared with digital simulation. The integration of multifunctional circuit blocks, both digital and analog circuits, in a single chip or multichip module prompted the need for mixed-signal simulation. As clock speed of a digital circuit goes higher, analog behaviors of some parts of the circuit become important and therefore generated the need for mixed-signal simulation as well. Mixed-signal simulators usually have the balance of digital speed and the accuracy of the analog circuit simulation. Analog simulation is needed for high-speed analog and RF circuit analyses; it requires correspondingly accurate device models for better solutions. When the circuit speed moves even higher or the system size shrinks further, full-wave electromagnetic solution of the circuit becomes a necessity, therefore the need for field or hybrid simulation packages, which is the focus of this book. In this chapter, we focus on the basic circuit theory and transient simulation technique for analog circuits. First the fundamental circuit device description is introduced, and the transient analyses of linear circuits are described, including the nodal and modified nodal analysis method. Based on the linear circuit transient analysis, the nonlinear device model, such as diode, BJT and MOSFET are introduced. Finally, the Newton-Raphson method to solve the circuit with nonlinear components is explained. Efforts are made to relate the circuit theory to the field equations introduced in previous chapters. Keep in mind that this chapter serves only as an introduction to circuit simulation, so the hybrid circuit cosimulation can be introduced in the following chapters. Material worthy of a whole book is condensed into this one chapter; and there are many good references for circuit simulation with much detailed theoretical analysis and formula derivation.
On the Effect of Operational Amplifier Gain-bandwidth Product on the Performance of Basic Building Blocks
Published in IETE Journal of Education, 2022
The opamp can be modeled in several ways. The routine hand analysis of circuits usually uses the opamp finite gain model (2), and the student should only know how to write using Kirchoff’s current law (KCL), the equations at each node and then the circuits can be analyzed using matrix methods or solutions by hand for deriving the transfer function, input and output impedances. Circuit analysis programs like SPICE, however, based on a description of the circuit – how components are connected between various nodes – use the modified nodal analysis to derive the frequency response, analyze noise, etc. On the other hand, another way of analyzing analog circuits in a computer-aided manner is known as Symbolic analysis. In this technique [10,11], the active devices such as opamp, Current Conveyor (CC), Operational Transconductance Amplifier (OTA), etc. are modeled using pathological elementsviz., nullor (comprising of a nullator and a norator), Voltage mirror – Current mirror (VM-CM) pairs. The equations describing the complete circuits can be derived using standard nodal analysis and analyzed using matrix methods. The transfer functions etc., can be derived in terms of various parameters in the circuit such as resistors and capacitors, as symbolic expressions. In this paper, we use the model of (2) and use only simple circuit analysis techniques.