ac amplifier

[jovabiot]

How can i implement a circuit for amplifier an ac signal of 50Mhz and 60mV to a signal of 5volts? Can i do it with transistors or maybe with operational amplifier? Can anyone says me the exactly circuit for this signal? thanks a lot

 

[Russlk]

you need a gain of 50/.06 = 83.3. Multiply this by 50 mHz and the result is 4.2gHz gain-bandwidth product. You won't find an op amp with that spec, so you will have to build it discrete. If the signal is narrow band, you can use tuned circuits but if it is wide band, some kind of R-C stage will be required.

 

[jovabiot]

the R-C requerired is before the amplifier? Can you say me the complete circuit, please? thanks. the transistor to use doesn't matter?

 

[Russlk]

Yes, the transistor matters. I can design the circuit, but need to know the frequency range.

 

[jovabiot]

I am modulling a bpsk with 50 Mhz, then the amplifier must work centered at this frequency and with a bandwidth of 10 or 20 Mhz. Is it possible? How is the circuit? thanks

 

[Roff]

You are asking for 5 volts out. Do you need a logic signal for TTL or CMOS?

 

[jovabiot]

it can be for TTL and for CMOS, i don't know witch logic i am going to use, maybe TTL, but i'm not sure. Thank you

 

[Roff]

it can be for TTL and for CMOS, i don't know witch logic i am going to use, maybe TTL, but i'm not sure. Thank you

I phrased my question poorly. Are you going to use the 5 volt output from this amplifier that you are asking for as the input to a logic device?
If so, you need a comparator. Take a look at Linear Technology's LTC1715. This should work for you.

 

[jovabiot]

ahhh... not, i am not going to use this signal with logic. i need a 5 volt analog amplitud . Thanks

 

[jovabiot]

can anyone help me??

 

[Roff]

Do you need 5 volts peak-to-peak, or 5 volts peak (10v p-p), or 5v RMS?

 

[jovabiot]

i need 5 volt peak-peak, i.e. , 2'5vol of amplitude. Thanks

 

[jovabiot]

help me!!!

 

[Roff]

This should work. The supply voltage has to be 10 volts or less. You could use +/-5V, which would allow you to eliminate the bias divider on the input. The high side bandwidth is over 200MHz, which might be a problem.
The LMH6626 is a dual current feedback amplifier. Layout needs to be very tight, using SMT components and a good ground plane. Stray capacitance on the inverting inputs can cause stability or frequency response problems. The resistor values are not arbitrary. Current feedback amplifiers are very sensitive to feedback component values.