Pablo,
A few quick answers:
- In RF out, why does the TI recommended circuit for impedance matching connects the inductor and the capacitor to Vcc? Calculating a normal impedance matching circuit I would have connected the components to GND. EH: You need to feed dc bias current into the PA. Also, the match is AC bypassed to gnd with the bypass caps on the VCC line (3V_RF). In other words, the match is AC grounded.
- According to datasheet, input impedance is (70-j26)ohms at 433MHz. But if I analyse the matching network with 50 Ohms load (antenna) and the component values specified in datahseet, I obtain 60.5-j9.4 approximately: EH: You forgot to include the TX matching parts -- they influence the RX match. Also, you have to include component parasitics at 433 MHz and also the PCB traces. Model caps as series RLC. Model inductor Q (resistive part) and also SRF.
Regards,
Eric Hooker
RF Consultant
