RFRXD0420T-I/LQ データシートの表示（PDF） - Microchip Technology
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RFRXD0420T-I/LQ Datasheet PDF : 32 Pages
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rfRXD0420/0920
FIGURE 3-3: FREQUENCY PLANNING WORKSHEET
Step 1: Identify receive (frf) and IF frequency (fif).
frf =
____________________
frf
fif
flo
fif =
____________________
Step 2: Calculate crystal frequencies for high- and low-side injection:
High-side Injection
fXTAL x PLL divide ratio
fXTAL-HIGH =
( ) frf + fif
PLL divide ratio
( ) _________ + _________
=
= _______________
16 if rfRXD0420
32 if rfRXD0920
Low-side Injection
fXTAL-LOW =
( ) frf - fif
PLL divide ratio
( ) _________ - _________
=
= _______________
16 if rfRXD0420
32 if rfRXD0920
Step 3: Calculate Local Oscillator (LO) frequencies (flo) using fXTAL-HIGH and fXTAL-LOW:
High-side Injection
16 if rfRXD0420
flo-HIGH = fXTAL-HIGH x PLL Divide Ratio =
_________ x
= _____________
32 if rfRXD0920
Low-side Injection
16 if rfRXD0420
flo-LOW =
fXTAL-LOW x PLL Divide Ratio =
_________ x
= _____________
32 if rfRXD0920
Step 4: Select high-side injection (flo-HIGH) or low-side injection (flo-LOW) that corresponds to the LO frequency
that is between the ranges of:
Device
rfRXD0420
rfRXD0920
LO Frequency Range
300 to 430 MHz
800 to 915 MHz
Step 5: From the chosen injection mode in Step 4, write the selected crystal frequency (fXTAL) and circle
injection mode.
fXTAL =
____________________
(circle one)
High-side Injection Low-side Injection
Step 6: Calculate image frequency (frf-image) for the Injection mode chosen:
if High-side Injection
frf-image = frf + (2 x fif)
if Low-side Injection
= ___________ + ( 2 x ___________ ) = ______________
frf-image = frf - (2 x fif) = ___________ - ( 2 x ___________ ) = ______________
Note: Image frequency should be sufficiently filtered by the preselector for the application.
DS70090A-page 10
Preliminary
2003 Microchip Technology Inc.
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