ADL5602

Hi Everyone,

I want to use ADL6501 to achieve maximum gain. In order to get the mentioned gain in the datasheet at my frequency band of interest (1520 - 1820 MHz), the input impedance of amplifier should be matched to 50 ohms which is my system characteristic impedance.

Could you please give a brief explanation on which data to be used as S11 to be matched for input impedance to achieve maximum gain?

Regards

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  • 0
    •  Analog Employees 
    on Nov 19, 2012 8:41 PM

    I think that it will be difficult to get a lot more gain out of ADL5602 in the 1520-1820 MHz range. From the s-parameter plot (Figure 5 in Rev. 0 datasheet), you can see that the input and output return loss in this frequency range is the 11-13 dB range. So, for example, if you could improve the S11 then there will be more power delivered to the device which will give you more output power. However, I don't think that the benefit will be large because the input return loss is already quite good. If the return loss is -12 dB, that means that one sixteenth of the power incident on the amplifier's input is being reflected back. So even if you could reduce the input return loss to minus infinity, the power delivered to the load would only increase by about 0.25 dB.

    If you do want to try this, I would suggest an experimental approach rather than an analytical approach. You can try to add shunt matching components at the input and output. Basically you put the amplifier eval board on to a network analyzer and then experiment with cap sizes and locations, much in the same way as the matching of a driver amplifier is optimized (see ADL5320 datasheet to get more insight on this).

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  • 0
    •  Analog Employees 
    on Nov 19, 2012 8:41 PM

    I think that it will be difficult to get a lot more gain out of ADL5602 in the 1520-1820 MHz range. From the s-parameter plot (Figure 5 in Rev. 0 datasheet), you can see that the input and output return loss in this frequency range is the 11-13 dB range. So, for example, if you could improve the S11 then there will be more power delivered to the device which will give you more output power. However, I don't think that the benefit will be large because the input return loss is already quite good. If the return loss is -12 dB, that means that one sixteenth of the power incident on the amplifier's input is being reflected back. So even if you could reduce the input return loss to minus infinity, the power delivered to the load would only increase by about 0.25 dB.

    If you do want to try this, I would suggest an experimental approach rather than an analytical approach. You can try to add shunt matching components at the input and output. Basically you put the amplifier eval board on to a network analyzer and then experiment with cap sizes and locations, much in the same way as the matching of a driver amplifier is optimized (see ADL5320 datasheet to get more insight on this).

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