I just started to learn how to use op amps recently.
The project needs to amplify a small signal with a Vpp of 20mV (with a DC bias of 1V) to 0~4V
I am going to use a bandpass filter to filter out high frequency noise and DC components and then amplify it to 0~4V.
The simulation is as follows:
Can I ask you if the op amp in front can be powered by a single power supply?
Because the post-amplifier has a DC bias, the input will not become negative.
It is still necessary to add a DC bias to the filter, but the band-pass filter will filter out the DC bias.
Or to change the plan?
Nathalia Posted on November 3, 2020
Not possible.
The capacitor C2 is used to remove the DC component, and the voltage across R4 is a positive and negative AC signal.
Billie Posted on November 3, 2020
Oh, if I want to use a 5V to -5V DC/DC chip, how should I choose? Is there any recommendation?
Nathalia Posted on November 3, 2020
The single-chip op amp consumes little current, so you can consider using the ICL7660 charge pump chip to convert 5V to -5V.
Perry Posted on November 3, 2020
Several problems in the first image
[1] R2 and C1 form a low-pass filter, and R4 and C2 form a high-pass filter. Together, they form a band-pass filter circuit? [2] OP1 has constituted the same-phase amplifier, what is the role of R3?
[3] The enlargement ratio of OP1 is (1+2.94/29.4)=1.1V, and then after OP2 in-phase amplification, the ratio is (1+9.16/11.1)*1.1=2, which is not enough to change the peak-to-peak value of 20mv to 0 -4V range
[4] What is the role of R7? Why is there no such resistance before the OP1 input
[5] V15 should not be a power supply op amp. Why is there no power supply for the op amp in the picture? Is it already set in the device in the simulation software?
