CC2420 Chipcon AS, CC2420 Datasheet - Page 47

• Manufacturer Part Number: CC2420
• Description: 2.4 GHz RF Transceiver for IEEE 802.15.4 and ZigBee
• Manufacturer: Chipcon AS

channel is clear. The TX_ACTIVE status
Frequency and Channel Programming
The
programming the 10 bit frequency word
located
operating frequency F
F
In receive mode the actual LO frequency
is F
Direct conversion is used for transmission,
so here the LO frequency equals F
2 MHz IF is automatically set by
so the frequency programming is equal for
RX and TX.
VCO and PLL Self-Calibration
VCO
The VCO is completely integrated and
operates at 4800 – 4966 MHz. The VCO
frequency is divided by 2 to generate
frequencies in the desired band (2400-
2483.5 MHz).
PLL self-calibration
The VCO's characteristics will vary with
temperature, changes in supply voltages,
and the desired operating frequency.
Chipcon AS SmartRF ® CC2420 Preliminary Datasheet (rev 1.0), 2003-11-17
C
= 2048 + FSCTRL.FREQ[9:0] MHz
C
– 2 MHz, since a 2 MHz IF is used.
operating
in
FSCTRL.FREQ[9:0].
frequency
C
in MHz is given by:
is
set
CC2420
C
. The
The
by
,
SmartRF
bit (see Table 5) may be used to detect
the result of the CCA.
IEEE 802.15.4 specifies 16 channels
within the 2.4 GHz band, numbered 11
through 26. The RF frequency of channel
k is given by [1] :
F
For
FSCTRL.FREQ register should therefore
be set to:
FSCTRL.FREQ = 357 + 5 (k-11)
In order to ensure reliable operation the
VCO’s bias current and tuning range are
automatically calibrated every time the RX
mode or TX mode is enabled, i.e. in the
RX_CALIBRATE,
TX_ACK_CALIBRATE control states in
Figure 23 on page 40.
C
= 2405 + 5 (k-11) MHz, k=11, 12, ..., 26
operation
®
in
TX_CALIBRATE and
channel
CC2420
Page 47 of 85
k,
the