### Q

In ADF4360-7's datasheet, it says: "Experiments have shown that the circuitshown in Figure 30 provides an excellent match to 50 Ω over a limited operating

range of the ADF4360-7 (850 MHz to 950 MHz). " Here the value of the inductor

is 7.5 nH. But in the "ADF4360 impedance match.xls ", When the frequency is

0.8GHz~0.9GHz, the Inductor value is about 40~50. So I am not sure which

inductor should should be the series L, is it the 47nH or 7.5 nH in the Figure

30?

### A

In the table, the R and X value shows the idea impedance due to frequency. TheSeries L column just shows if you want to tune the X to 0, the series

inductor's value that you need to add. (It is NOT means the shunt L 47nH)

But in real case, the bond wire and PCB parasitic capacitance will change the

output impedance, the final impedance before the inductor may become totally

different. For example, Z0=63-j240, if PCB parasitic capacitance equal to shunt

1pF, the final impedance is about 10-j100.

So experiments are very important here, as we have no way to accurate count all

the factors.