I am currently working on a amplifier circuit on 8Mhz signal (around -40dbm). The amplifier is based on a IC chip (lm7171 bin). The problem is, the amplifier works perfectly individually (correctly gives +20dB gain), but when we cascade two of them together, it only amplifes +6dB in total. It is supposed to give +40dB gain. It is probably not a problem of op-amp saturation.
Below is how we cascade our circuit. (VCC=15V, Vee=-15V)
Also, the datasheet is here:http://www.farnell.com/datasheets/1769090.pdf Decoulping capacitor is also connected between the source.
For decoupling, I use 4 capacitors for each amp (Vcc=15V, Vee=-15V)
Two op-amp works good individually (without connecting them together). And When I meassured the midpoint between two op-amps, it gives +20dB gain. This circuit is in breadboard.
(please note that this is not the circuit I am having now, this is what I had before. Notice that in the picture, two op-amp are not connected together. I can't take a photoshot of the current circuit because I don't have them with me. But the only change I make is simply connect them together and change the Rg value a little bit).