About MW7IC2725N reference design

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About MW7IC2725N reference design

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feiwang
Contributor II

We referred to the reference design in MW7IC2725N datasheet. The issue is VD2 connected to the drain of the transistor. Why is it short circuit of RF via the bypass capacitors in my simulation? How do you resolve it? Thank you.

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  • RF

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LPP
NXP Employee
NXP Employee

> How do you resolve it?

General practice is to put DC bypass capacitors at quarter-wave distance from the output pad. Feeding in the DC via a λ/4 transformer will transform the short circuit into an open circuit which has no effect on the signals on the line. For this specific substrate the required distance is about 705 mils.

In the case of MW7IC2725NR test board layout, capacitors are located closer and they would damp output RF signal. At the moment, i do not know the reasons beyond the layout of this board. Hope, i will get a reply from our application engineer soon.
Have a great day,
Pavel

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feiwang
Contributor II

Hi Pavel,

Thank you for the quick response and thank you for your honesty.

I have looked at the data sheets for many NXP devices and it appears that the MW7IC2725N and its sister MHT2000NR1 are the only one with these large capacitors shunting the RF line.

We wish to buy upto 30 MW7IC2725N parts and manufacture our boards. So we would like to know if the capacitor locations are a mistake or not. We would like an explanation for the location and purpose of C13, C14 and C15.

Thank you

I look forward to heaing from you soon

BR

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