The app note says to enter permittivity for 2.45Gz as 4.1, tan loss 0.0155. The width of the trace is 0.254 mm, the gerber document says that the FR4 thickness is 1.6 mm. The app note suggests to calculate the impedance of the traces (from pad to pad) for the balun part. 20 + j0 is the Thevenin equivalent impedance (Zout).
It marks the trace to take the impedance of the trace in calculation. "It ignores the dc blocking cap as the values are large". The IC's (CC2500) datasheet defines the optimum load at RF_P and RF_N as 80+j74 ohm.įrom figure 6 on page 7, it shows the differential circuit, and the below figure (figure 7) shows the single part where the impedance is divided by 2. I would appreciate if someone could tell me what/where am I doing wrong?īlue part is the DC blocking cap, C10-L1 and 元-C11 are Balun, the grey part is PI network.
I am having problem to verify what an app note ( AN068) explains to calculate Balun values.
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