ML7436N LSI Hardware Design Manual
FEXL7436NDG-01
16
The impedance moves to 50+jX when the inductor Lmatch is connected on the Smith chart as following
Figure 7.6
.
Figure 7.6
Impedance conversion with Lmatch addition
In fact, there are two Lmatch values whose real part is 50Ω. Each Lmatch values convert input impedances to (1)50+jX,
(2)50-jX. In case of (2)50-jX, Lmatch is too large value, it is difficult to adjust Lmatch value. LAPIS technology
recommends adopting (1)50+jX.
7.1.3.
Adjustment of LNA input impedance imaginary part to 0Ω
Figure 7.7
shows the capacitor Cmatch series connection. It adjusts the LNA input impedance imaginary part to 0Ω.
Figure 7.7
Addition of Cmatch
The required capacitance is calculated by the formula (2).
LNA input impedance
(1)
Lmatch connection
50+jX
(2) 50-jX
