Advantages And Disadvantages Of Op-Amps

One of the most common ways to parametrize a circuit is by using the equivalent model of the transistor to the small signal analysis (used for low frequencies), or the S-parameters analysis, especially for RF circuits. However, these tests are only accurate enough for sizing linear devices, which is not the case of power amplifiers. Thus, it is necessary to resort to the analysis of large signals. For large signals, both the output and input impedances have to consider the values of frequency, DC voltage, output power, temperature, input power and

CMOS technology is very near to its scaling limit. Using the VLSI technology, in the recent past, researchers are facing some limitations, from practical point of view, in the approaches of CMOS technology like the short

KVL, KCL and Ohm's Law are all important tools for circuit analysis, especially using the node voltage method. A worked example for KCL and Ohm's law is included for Figure 1 next; which can also be directly applied to that of KVL in the same manner in place of KCL.

Abstract — Using Moore’s law, we will continue to get abundant transistors which only will be limited by the amount of energy consumed. Energy efficiency can be improved to many orders of magnitude with the help of Near Threshold Voltage (NTV). There are various Design techniques required for reliable operation on a wide range of input voltage – from very low to sub threshold region. Coming to the systems designed for NTVs, they can select their modes of operation dynamically from very high performances, to high efficient energy modes and also to lowest power.

Advances in electronic design tools have validated Moore’s law (as applied to the complexity of integrated circuits) and have helped achieve amazing standards in computing power while simultaneously decreasing costs. For designers of automotive systems to duplicate and manage similar levels of complexity, design tools that automate the

A gradient algorithm is proposed where the gradient of clipping noise mean square error is calculated and optimization of signal to clipping noise ratio is done in place of peak to average power ratio and order of complexity is O(N). A truncated IDFT algorithm is proposed where in place of calculating entire IDFT values, it calculates on maximal IDFT element thus reducing complexity of optimization process. The basic idea is to divide the group in two halves of N/2 and leave the half with lesser energy and move in similar way till we reach the maximum energy element, however this scheme may not always give correct maximal IDFT element, it also costs in lower peak to average power ratio reduction.

Also, the dynamic range is degraded by these strict limitations. Upwards, the dynamic range is lowered due to the reduced signal headroom as a result of reduced supply voltage. Downwards, the dynamic range is limited by larger noise voltages due to curtailed supply currents. The only way to make the operational amplifier survive the trend towards lower supply voltages without weakening its characteristics, is by developing very efficient operational amplifier topologies that combine low voltage and low power operation and be as simple as possible to save die area, in its contemporary sense. In this thesis, we design and analyses different design approach of operational amplifier circuits using power gating technique and MTCMOS leakage reduction techniques. Both these techniques are very effective for reducing leakage power and group delay, increasing gain margin in electronic devices. Here, power gating technique is used to reduce leakage power, group delay and increase gain and phase margin.

The CA3140A and CA3140 are integrated circuit operational amplifiers that combine the advantages of high voltage PMOS transistors with high voltage bipolar transistors on a single monolithic chip. The CA3140A and CA3140 BiMOS operational amplifiers feature gate protected MOSFET (PMOS) transistors in the input circuit to provide very high input impedance, very low input current, and high speed performance. The CA3140A and CA3140 operate at supply voltage from 4V to 36V (either single or dual supply). These operational amplifiers are internally phase compensated to achieve stable operation in unity gain follower

The semiconductor industry constantly demanding greater features miniaturization, device density and lower cost. It has motivated the combination of analog circuit with digital subsystem. Analog circuits contain extremely sensitive circuits e.g. opamp and comparator which can take a few µvolt of signal at their input and convert them to several volts at their outputs. Digital circuits on the other hand operate with rapidly switching waveforms

Abstract: A new CMOS clocked dynamic comparator using two input single output differential amplifier as latch stage suitable for high speed analog to digital converters with the performance of high speed, low power dissipation and low immune to noise. The conventional dynamic comparator requires more power and has more delay. A conventional double tail dynamic comparator consumes less power and works at high speed than its predecessor, the conventional comparator. There is very much need to reduce the delay and power consumption which is possible by strengthening the positive feedback during the regeneration. This can be achieved by adding few transistors to the double tail dynamic comparator. Using the inverter based differential amplifier to design a novel double tail comparator for reducing the no of transistors and better characteristics. The performance of this method is to be analyzed with the existing two designs at different power voltages and frequencies using 0.18μm CMOS Technology.

Abstract :A new CMOS clocked dynamic comparator using two input single output differential amplifier as latch stage suitable for high speed analog to digital converters with the performance of high speed, low power dissipation and low immune to noise. The conventional dynamic comparator requires more power and has more delay. A conventional double tail dynamic comparator consumes less power and works at high speed than its predecessor, the conventional comparator. There is very much need to reduce the delay and power consumption which is possible by strengthening the positive feedback during the regeneration. This can be achieved by adding few transistors to the double tail dynamic comparator. Using the inverter based differential amplifier to design a novel double tail comparator for reducing the no of transistors and better characteristics. The performance of this method is to be analyzed with the existing two designs at different power voltages and frequencies using 0.18μm CMOS Technology.

The third source of power dissipation is leakage power dissipation. In the MOSFET, the leakage current comprised of six short channel mechanisms. Reverse bias PN junction leakage, sub-threshold leakage, gate oxide leakage, gate current due to hot carrier injection. Gate includes drain leakage and channel punch through current. Among these components the two main contributes

In earlier stages of VLSI circuit design the emphasis is on Area and Speed optimization giving concerns to Packaging and Efficient designing. As the technology scales down according to predictions of Moor’s Law, it is advent that the CMOS dimensions have been scaled down drastically. But due to increase in use of Portable Devices Such as Cellphones, Laptops, Personal Health Monitoring systems, there has been a demand of higher battery life for Portable devices. Whereas big data centers which contains large set of circuits consumes tremendous power and dissipates large amount of heat which incurs huge cost to maintain. The solution for these problems is to design circuits which consume low power which give rise to the concept of Low-Power VLSI designing.

In this paper, we present such an approach, a low-Voltage CMOS analog digital circuit in current-mode where it works with a supply voltage of VDD=-VSS=2V. The circuit is based on the four-quadrant CMOS analog multiplier (Ali et al., 2009).

Sigma-Delta modulator is designed with the bandwidth of 10 MHz and sampling frequency of 350 MHz. The modulator is designed using a Matlab code and the circuit is then designed on SIMULINK. The evaluation indicates that the second order modulator achieves 73.5 dB peak SNDR and 73 dB of peak SNR.