TDA5212_06 INFINEON [Infineon Technologies AG], TDA5212_06 Datasheet - Page 27

• Manufacturer Part Number: TDA5212_06
• Description: ASK/FSK 915MHz Single Conversion Receiver
• Manufacturer: INFINEON [Infineon Technologies AG]

Wireless Components
4.4 Crystal Frequency Calculation
As mentioned in Section 3.4.3 the local oscillator (UHF PLL) signal has to be
high-side injected for a RF below 921MHz and low-side injected for a RF above
921MHz into the downconverting mixer. Thus the crystal frequency is calcu-
lated by using the following formula:
with
This yields the following calculation for a RF of 915MHz for instance:
CSEL tied to GND
Table 4-1 PLL Division Ratio Dependence on States of CSEL
1.In the Infineon Evalboard the L0 is used in low side injection mode and therefore
crystal with 14.1296875MHz is used. But to guarantee the function over the whole
temperature range the L0 has to be used in high side injection mode for a RF of
915MHz (see also VDO frequency range).
ƒ
ƒ
ƒ
r
RF
LO
QU
CSEL
open
GND
1
:
f
....
....
....
....
QU
4 - 6
=
915
receive frequency
local oscillator (PLL) frequency (ƒ
crystal oscillator frequency
ratio of local oscillator (PLL) frequency and crystal
frequency as shown in the subsequent table.
MHz
f
QU
64
+
=
10
f
7 .
RF
MHz
±
r
10
7 .
=
14
.
4641
Ratio r = (f
Specification, December 2006
MHz
128
64
LO
RF
/f
±
QU
Applications
10.7)
TDA 5212
)