I feel that some points should be sorted out.
You have been originally asking how to amplify µV signal to mV, with minimal supply voltage.
Later you switched to 1.45 V input voltage and 8V supply. I guess you did so to have a simple problem description. But the solution will be probably different, hence we should agree if we are discussing the first or the latter question. I'm referring to high level amplifier here.
It has been already stated, that the single supply circuit in post #19 only works with an OP that has a input common mode range including the negative supply rail. NJM4558 isn't of this kind. Even with respective OP common mode range (as exposed e.g. by LM358), the inverting single supply amplifier can't amplify a positive input voltage, as also stated.
There are several solutions:
- use dual supply which enables the circuit to amplify signals of positive and negative polarity
- use an OP with input common mode range down to and including the negative supply rail
To amplify a positive input voltage > 1V, NJM4558 can be even used in a non-inverting single supply amplifier configuration. See a simulation circuit with similar RC4558. Please notice that these OPs have no guaranteed common mode voltage range for +/-4V supply, the simulation is based on typical values. The LTspice circuit is also attached.
View attachment 157799
There is no answer, because there is a lack of information.so you are saying if i use a dual supply that will fix the second issue? i
this is a schematic of the circuit
View attachment 157816
0v is the negative terminal. and +in is connected to the negative terminal. i think i am using a single supply power source. so will a dual supply power source work?
I believe, you either don't read the answers or don't understand it. I have no other explanation for seeing the circuit in post #45 that has been already recognized as non-working. If you want to change it into a dual supply circuit, why you don't sketch it so?nobody has answered my question.
Yes, if you refer to typical OP specs. Not necessarily, if you rely on guaranteed parameters. I presume you read the datasheet and noticed the difference between typical and minimal voltage values, also the lack of specifications for +/-4 V supply.so if i use njm4558 in a non-inverting single supply amplifier configuration that will amplify a positive input voltage that is greater than 1 volt?
Audioguru did in the previous post.
No.i have built an inverting amplifier. it uses a dual power supply.
This is your mistake.the rail that serves as ground
Hi,
This is your mistake.
On a dual supply Opamp none of the supply rails is GND.... (with standard node naming)
Klaus
so how do i create a dual power supply?
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