Voltage Amplifier at 1MHz, 40dB

[aviaden]

Voltage Amplifier

Hi,
I need help in designing a voltage amplifier. My input signal is a few mili volts, around 1 MHz, and i need a gain of at least 40db.
I tried some circuits but nothing worked well...
I will Appreciate any help....circuits, PSpice files or any other ideas...
Thanks, Aviad.

 

[electrik1]

Re: Voltage Amplifier

check the Gain Bandwidth product of your opamp(in the datasheet). not every opamp can give you 40db at 1 MHz. you are going to need a very high frequency opamp.

 

[aviaden]

Thanks for the answer.
Actually i'm using a high freq opamp- AD8042, in "clasic" non inverting circuit.
Any other ideas?

 

[LvW]

As the AD8042 has a gain of app. 40 dB at 1 MHz, this is not sufficient for a closed loop gain of app. 40 dB.
Try to use an opamp which has at least 500 MHz GBW. This opamp needs not to be compensated. What about a current feedback amp ?

 

[aviaden]

Thank's for the reply.
1) Are you femilier with such a opamp? With a BW of 500 MHz?
2) Can you send me a link/ add a scheme/ describe this kind of current feedback amplifier circuit?

Thank's, Aviad.

 

[LvW]

There are many opamps resp. current-feedback amps (CFA) which have high frequency capability; for example the AD8001 has a unity gain frequency of app. 800 MHz.
This is a CFA which can be used like a non-inverting opamp circuit - provided you select the feedback resistor as recommended by the mnufacturer (data sheet).