The impedance matching of PCA10028 referance Layout

[eaglezcy]

hi ： I get the PCA10028 layout, and find that the impedance matching demand that the impedance of transmission line is 50Ω as shown the following picture. the mid-layer1 and mid-layer2 of the PCA10028 layout are cut off, so I am confused about the impedance matching.

There are questions as blow:

1. What is the copper and dielectric thickness of the top layer、mid-layer1、mid-layer2、bottom layer? 2.From the website as below, I know that the copper thickness is 0.35um for each layer, and the dielectric thickness is 0.8mm totaly. devzone.nordicsemi.com/.../

So I caculate the impedance for the transmission line with the methods here.
emclab.mst.edu/.../index.html

The result is shown as below, it is not 50Ω......So Where is the problem?

[Susheel Nuguru]

The impedance in this point is not 50 ohm. It will only be 50 ohm at the end of the matching network, after C5. The inner layers are removed do reduce parasitic capacitance to ground. Keep the components close to reduce track inductance.