role of certain elements in MACOM PCB

[yefj]

Hello,given the macom amplifier shown below.i have two place which i am not sure about.
1. place marked as 1 in the photo looks like output pin but i am not sure why its needed?
2.in place marked 2 why there is a thick trace with a gap ?
Thanks.
https://cdn.macom.com/datasheets/CGHV1A250F.pdf

 

[vfone]

Connector nr. 1 could be a DC current sensor, where the black wire W1 could be the shunt resistor.
Nr. 2 could be the place on the PCB of the big 3300uF capacitor.

 

[yefj]

Hello Vfone,given the schematics below, i know that element 4 is RF GND.
What is the role of rectangles 1,2 ,3?
i cant see element 1 in the layout shown below.

https://cdn.macom.com/datasheets/CGHV1A250F.pdf

 

[volker@muehlhaus]

What is the role of rectangles 1,2 ,3?

Transmission line.
Line 2 and 3 are designed for 50 Ohm line impedance, length is not critical.
Line 1 in the DC feed has higher line impedance and length approximately lambda/4.

 

[vfone]

Line 1 is shown in the attached picture..

 

[yefj]

Hello, given the photo below could you please say where are the 50 ohm lines an where the length sould be lambda/4?
Thanks.

 

[vfone]

The lines with the length lambda/4 I marked with an arrow.
These lines are not 50ohms, but high impedance lines (their width is thinner than the width of a 50 ohms line).

 

[yefj]

Hello Vfone,there is a very beig width transition from the place where the trace is touching the VDD(very very thick)
then it have a very sudden transition to very thin width.so i am worried of two things.
1. the transition from very wide to much less wide could cause impedance mismatch.
2.although its based on the manufacturer evolution board the bigger concern is that this trace carrying power to the drain will burn because at the destination the line is very narrow compared to where its started.
how do you reccomend to to the transition?
Thanks.

 

[volker@muehlhaus]

Do you mean the "outline" lines at the very beginning and very end, which are not filled? This is a problem with your data import, this must be filled 50 Ohm lines also.

 

[yefj]

Hello Volker , i mean the DC power rail, the RF lines i know it needs to be 50Ohm.
you see that power rail starts very wide then suddenly goes very thin.
if you see some points where it could improve it will be great.
Thanks.

 

[vfone]

It is true, theoretically is nonsense to have the DC line very wide and then very thin. But because the DC current is very high (18A) the line should be wider as possible. The line is thin, only in the place where need to be thin, where the line is high impedance.