[AK1222]

MS1314-E-02

2014/10

- 25 -

14. Application Information

•Impedance matching network with LC

Figure 22. Impedance matching network with LC

Impedance matching network with LC is shown in Figure 22. AK1222 has open drain outputs, so RL1 + RL2 is

output load resistance. C11 and L11 compose lowpass filter. C12 and L12 are for highpass filter. C13 is DC

blocking capacitor and L13 is RF choke. IFOUTP and IFOUTN pins need power feeding via L11, L12 and L13.

The differential voltage from IFOUTP/N can be converted to a single-ended by L11, L12, C11 and C12 properly.

The differential impedance (RL1 + RL2) is converted to single-ended output terminating impedance Ro.





O

L2

L1

OUT

12

11

*

*

*

π

2

1

R

R

R

f

C

C











OUT

O

L2

L1

12

11

*

π

2

*

f

R

R

R

L

L







For example, in the case of IF Output = 50MHz, Output Load Resistor (Rload) = 2.2k

 in 50 interface, L11,

C11, L12 and C12 are calculated as below.