Expected Gain of ADL5565

Dear Sir/Madam,

I have two questions.

1) Can I replace your transofrm T1/T2 to jumpers?

I just bought your ADL5565-EVALZ.

And I am tring to use without transforms T1 and T2.

Please refer to fig-45 on page 24 your datasheet rev-c.

I removed T1 and T2 and put the jumper wires on T1 and T2 .

So I just put the condition that R1=R2 are open(not installed).

Due to your table-17 on your datasheet, I believed the Gain=15.5dB.

But the result I got was Gain=0dB not 15.5dB. Why this result has come?

Test input signal is 1.76GHz/230mVp-p.

Is 1.76GHz too high frequency for input?

2) Why did you choice that T1/T2 are ETC1-1-13 (M/A-COM)s on your evalboard?

I just confirmed the ratings of your T1 and T2 on your eval board ADL5565-EVAL.


Band width of ETC1-1-13 is 4.5MHz to 3000MHz.

But your ADL5565 can drive 6GHz.

So ETC1-1-13 does not fit for 6GHz drive I think.

Why did you choice this transform ETC1-1-13??

Thanks Kaos

  • Hello Jim,

    Thank you for you reply.

    To replace T1 to jumper, does this affect to frequency-characteristic?

    I dont think so....correct?

    Thanks ,Kaos

  • The gain  specified in the ADL5565 datasheet is voltage gain not power gain. T1,R1, snd R2 are used to perform a 50 ohm single ended to differential conversion and match the input of theADL5565 to 50 ohms differential.

    T2, R7, R8, R9 and R10  areused to create a 200 ohm load and convert it to 50 ohms single ended. There is a loss of 11 dB associated with this network. Optimal distortion is achieved when driving a 200 ohm load.

    Even though the ADL5565 has a very wide bandwidth its primary use is for driving ADCs at IF frequencies. At 2GHz the device has ~ 15 dB of voltage gain. ( see figure figure 3)  What instrument are you using to measure the gain? Other parameters such as P1 dB, distortion and IP3 are reduced as frequencies increase.  What is your application? What is the impedance of the device driving the ADL5565? Wha tis the ADL5565 driving in your application?

    The ETC1-1-13 transformers are the widest bandwidth transformers commercially available at this time. That is why they were chosen for the evaluation board.

  • You need to drive the part differentially via differential source or use a transformer to do the conversion.

    To configure the part for a  50 ohm single ended input see figure 35 in the ADL5565 datasheet.