ADL5201 or ADL5202 in cascade configuration

For our receiver design, we needed high gain amplifiers and wide range of gain control in the Intermediate Frequency (IF) section. Our IF frequency is 21MHz and we need >60dB gain control range. I was thinking of two possible combinations:

1. Use two ADL5201 in cascade. I can get 63dB gain control range with up to 40dB of maximum gain

2. Use the ADL5201 instead and connect them back to back.

Looks like the input and output impedance of the ADL5201/5202 are the same at 150 Ohms. So i do not need an extensive match circuit between the amplifiers, if they are in cascade. I was hoping to use the schematic attached. We need 50 Ohm input and output impedance for the IF section. So we plan to use the input/ output 1:3 transformers.

Are there any issues in using this part in the configuration shown in the attached schematic ? Is there a preference in ADL5201 or ADL5202 in this configuration ? We were hoping to use the ADL5202 to reduce chip count.



  • 0
    •  Analog Employees 
    on Jun 21, 2017 11:04 PM

    Hi AB,

    Either approach should work, however, using the ADL5202 in tandem might be more layout dependent and tricky in terms of keeping datasheet performance. If space is not an issue, I would use the two ADL5201's in series.



  • Hi AB,

    I use two ADL5201 in cascade almost same as your first situation.

    The question is that the second stage performs well whose gain margin is -11.5dB~+21dB, while the gain margin of the first stage is only -17dB~+14dB, which is 5dB smaller than the standard.

    Following are the schematics of the two stages. I think there is something wrong with the design of the first stage, and most probably with the BALUN, but I can't figure it out. Could you give me some suggestions?