Amplifier with supply voltages of 0 and 5 volts.

[aviaden]

I'm trying to build a amplifier for a small signal, aound 2.5 volts.
Im using the AD8001 op amp. the signal is about 1 MHz, and of a few mvolts so i need a gain of about 40 db.
I've buid the circuits a described at the attached file.

First i used -5 and 5 volts as supply voltages for a signal around 0 DC. The circuit worked well.
But in my application i can't use -5 as supply voltage. so i've elevated the small signal to a DC of 2.5 volts, and used 0 and 5 as supply voltages. but i didn't get good results (No gain). I also tried to elevate the signal to 5 V DC and use 0 and 10 as supplies, but with no sucsses.

Please have a look at word file to see pspice simulations.

I will appreciate any help or ideas.
Thanks, Aviad.

 

[LvW]

Hi aviaden,

you should use a capacitor in series with the 390 ohms.
Thus, you have for dc 100% feedback (dc gain of unity). Thus, the input bias of 2.5 volts is transferred also to the output. Then, notice the highpass characteristic of your circuit.

 

[aviaden]

Thanks, it really solved the problem.
Aviad.