What reference design to follow to design a custom PCB for MKW21Z MCU?

[shantamraj]

I am designing a custom PCB for developing around MKW21Z MCU. As such there are no reference designs for it, however there are reference designs for MKW41Z (MKW21Z belongs to the same family and even the data sheet is the same). There are 2 reference designs for MKW41Z, the FRDM board and the USB sniffer. But here is the problem, there are 4 different ways in which the RF section has been shown to be implemented in the schematics and the Hardware User guides which are as follows -  

I want to use the Meander antenna because mine is a space constrained design more like the USB Sniffer.

Even in the images i found two different images (RF part is clearly different) for the USB Sniffer design. The first image is what is used for the Getting Started video. Here are the 2 images - 

As for the FRDM board, no close ups are available.

1) So which schematic should i go for?

2) Since there are only 2 hardware available but 4 different schematics, the hardware that NXP has made, follow which one?

3) Since MKW21Z works at the same frequency and belongs to the same family as MKW41Z, following the guidelines for      MK41Z shouldn't pose any problems in my design?

4) Is it necessary to have 50ohm controlled impedance line, given that the length of that trace will be extremely small, like 4-5mm maximum ?

5) Can you provide me a link for the dimensions of the meander antenna?

[jorge_a_vazquez]

Hi Shantam Raj

About your questions:

1) So which schematic should i go for?

2) Since there are only 2 hardware available but 4 different schematics, the hardware that NXP has made, follow which one?

You can see 4 different schematics for two boards because there are two schematic revision, Rev A1 and Rev A2. I recommend you Rev A2 of USB-KW41Z.

3) Since MKW21Z works at the same frequency and belongs to the same family as MKW41Z, following the guidelines for      MK41Z shouldn't pose any problems in my design?

Yes, as long as they works at the same frequency their antenna can be designed with the same guidelines.

4) Is it necessary to have 50ohm controlled impedance line, given that the length of that trace will be extremely small, like 4-5mm maximum ?

Yes, C47 and C48(or L6) were chosen to match to this impedance, this will ensure a correct transition.

5) Can you provide me a link for the dimensions of the meander antenna?

You can find in the downloads tab of the main page for USB-KW41Z, under schematics, a package that include all the designs files for USB-KW41Z for revision A1 and A2, it is named as USB-KW41Z Design Files.

USB-KW41Z|Wireless Packet Sniffer|NXP 

Hope this information helps you
Have a great day,
Jorge Alcala

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