Op amp investing buffer

Best Answer No, there is no way to make an inverting buffer with just an op-amp that does not depend on the resistor values. You can get resistors with very fine accuracy and stability at an equally impressive price or you can get networks with matched in value and in temperature coefficient where the absolute accuracy may not be so impressive but the ratio is tightly controlled. There is a way to invert a signal without accurate resistors- the so-called flying capacitor method, but it's fairly complex and resistors are a better solution for most situations down to ppm level accuracy.

Related Solutions Having the same source for power supply and positive input for a single-supply buffer amplifier The op-amp can't do anything useful in this configuration. You need to give it more supply voltage than the desired output voltage, even though it's "rail to rail". If you ask it to output 8V or even 11V with a 12V supply, it may be able to do that, provided the load is not too much for the op-amp to supply. In this case, that might be 10mA or so. In cases where a design calls for one input to be short-circuited to ground, that short circuit can be replaced with a variable resistance that can be tuned to mitigate the offset problem.

Operational amplifiers using MOSFET -based input stages have input leakage currents that will be, in many designs, negligible. Power supply effects[ edit ] Although power supplies are not indicated in the simplified operational amplifier designs below, they are nonetheless present and can be critical in operational amplifier circuit design.

Supply noise[ edit ] Power supply imperfections e. For example, operational amplifiers have a specified power supply rejection ratio that indicates how well the output can reject signals that appear on the power supply inputs.

Power supply inputs are often noisy in large designs because the power supply is used by nearly every component in the design, and inductance effects prevent current from being instantaneously delivered to every component at once. As a consequence, when a component requires large injections of current e.

This problem can be mitigated with appropriate use of bypass capacitors connected across each power supply pin and ground. When bursts of current are required by a component, the component can bypass the power supply by receiving the current directly from the nearby capacitor which is then slowly recharged by the power supply. Using power supply currents in the signal path[ edit ] Additionally, current drawn into the operational amplifier from the power supply can be used as inputs to external circuitry that augment the capabilities of the operational amplifier.

For example, an operational amplifier may not be fit for a particular high-gain application because its output would be required to generate signals outside of the safe range generated by the amplifier. In this case, an external push—pull amplifier can be controlled by the current into and out of the operational amplifier. Thus, the operational amplifier may itself operate within its factory specified bounds while still allowing the negative feedback path to include a large output signal well outside of those bounds.

Differential amplifier difference amplifier [ edit ] Main article: Differential amplifier Amplifies the difference in voltage between its inputs.

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In this configuration, the input is applied at the non-inverting terminal of the op-amp. As shown in Fig. Due to this negative feedback, the op-amp operates in the linear region. Negative Voltage Feedback in the Non-Inverting op-amp configuration Derivation of Closed Loop Voltage Gain of the non-inverting op-amp Configuration Here, it has been assumed that the op-amp is ideal op-amp, and no current is flowing into the op-amp terminals.

As shown in figure 2, the fraction of output voltage Vx is given as feedback to the input. That means the voltage at the inverting and the non-inverting input terminals will be the same. Moreover, the input impedance of the non-inverting op-amp is very high compared to inverting op-amp. Ideally, it is infinite, because, for the ideal op-amp, no current is flowing into the op-amp terminal And because of the high input impedance, the op-amp can be used as a buffer in many applications.

This arrangement is called an Op-Amp Follower, or Buffer. The buffer has an output that exactly mirrors the input assuming it's within range of the voltage rails , so it looks kind of useless at first. However, the buffer is an extremely useful circuit, since it helps to solve many impedance issues. The input impedance of the op-amp buffer is very high: close to infinity. And the output impedance is very low: just a few ohms. This means we can use buffers to help chain together sub-circuits in stages without worrying about impedance problems.