# Voltage gain and bandwidth relationship problems

### relation between gain & bandwidth. - The Student Room The circuit represents a system with positive gain, G and feedback, β. of feedback” and is often specified in decibels (dB) by the relationship of 20 log (1+ βG). The open-loop voltage gain, AVOL, of a standard op-amp is its voltage gain stabilisation against DC drift as well as increasing the amplifiers bandwidth. The bandwidth of an operational amplifier is a key factor in its performance and its amplifiers because relationship between gain and bandwidth is not linear. Could any one help me to gain a deep understanding about the speed of opamp. Is there any relation between the gain-bandwidth (GBW) of op-amp and its.

This exemplifies the fundamental trade-off of a negative feedback amplifier—we reduce the overall gain in order to improve the circuit in other ways. The point we have not yet explicitly made is that greater desensitization is achieved when the open-loop gain is higher and the closed-loop gain is lower. Recall the formula for closed-loop gain: The feedback network is designed for a gain of And even in devices that are specifically designed and optimized for high-frequency operation, parasitic inductances and capacitances will eventually cause the gain to roll off. The interesting thing is what happens to the frequency response; if you analyze the closed-loop gain as a function of frequency, you will find that the closed-loop cutoff frequency fC,CL is related to the open-loop cutoff frequency fC,OL as follows: Note also that, as with gain desensitization, higher open-loop gain leads to greater improvement in bandwidth.

Perhaps you have noticed something interesting here: This leads to the rather elegant relationship whereby decreasing the gain of the amplifier by a certain factor causes the bandwidth to increase by the same factor.

Sure, make A larger by increasing its gain or bandwidth.

## An Op Amp Gain Bandwidth Product

Increase the k by a factor of 10 or so. Or, you can increase the bandwidth by decreasing RP1 or CP1 by a factor of Run a new simulation. Did your new op amp extend the bandwidth at V 4? A simple equation gets you the answer. GN Noise Gain - the gain defined below.

## Negative Feedback, Part 2: Improving Gain Sensitivity and Bandwidth

Typically, noise is modeled as a voltage source at the positive input of the amplifier. So the non-inverting gain is used to calculate the resulting output. Does the noise gain equation look familiar? Adjust the gain by varying R2 and R1.

You should be able to predict the bandwidth at V 4 for any of your chosen gains. Why call it this? What does this mean?

### Negative Feedback, Part 2: Improving Gain Sensitivity and Bandwidth

You can't arbitrarily set the gain and bandwidth for a given op amp. This means that, at a gain of one, the bandwidth is 12 MHz, and at the maximum open-loop gain ofthe bandwidth is 12 MHz divided bywhich is 24 Hz.

This is the op amp open-loop cutoff frequency. The mathematical model of the gain bandwidth product is described by the following single-pole function: Figure 1 shows a Mathcad plot of this function. The markers show the cutoff frequency at 24 Hz and dB gain, and the unity-gain frequency at 12 MHz and 0 dB gain.

### Op Amp Bandwidth

Why is the gain dB at 24 Hz? Figure 1 For simplicity and clarity, the gain is always shown in dB. This theoretical graph is almost identical with the ADA open-loop gain characteristic as shown in its datasheet Rev. The advantage of using the gain bandwidth product parameter lays in the fact that we can always predict the op amp bandwidth for a certain gain. As an example, Figure 2 shows an inverting amplifier with ADA