CC400 Chipcon, CC400 Datasheet - Page 16

• Manufacturer Part Number: CC400
• Description: Single Chip High Performance RF Reansceiver
• Manufacturer: Chipcon

PLL Lock Indicator
The
on the LOCK pin. The PLL lock signal is
not 100% conclusive. That is, if the LOCK
signal indicates lock (i.e. a high signal on
the LOCK pin) the PLL has locked to the
Antenna Considerations
The
various types of antennas. The most
common
communication are monopole, helical and
loop antennas.
Monopole
antennas with a length corresponding to
one quarter of the electrical wavelength
(λ/4). They are very easy to design and
can be implemented simply as a “piece of
wire” or integrated into the PCB.
Non-resonant monopole antennas shorter
than λ/4 can also be used, but at the
expense of range. In size and cost critical
applications such an antenna may very
well be integrated into the PCB.
Helical antennas can be thought of as a
combination of a monopole and a loop
antenna. They are a good compromise in
size
antennas tend to be more difficult to
optimise than the simple monopole.
Chipcon AS
CC400
CC400
critical
PLL lock indicator is available
antennas
can be used together with
antennas
applications.
SmartRF
for
are
TM
But
CC400
short-range
resonant
helical
Datasheet (rev. 3.1) 2003-11-12
SmartRF
desired frequency. However, situations
might arise where the lock signal does not
indicate lock (i.e. a low signal on the
LOCK pin) when in fact the PLL has
locked to the desired frequency.
Loop antennas are easy to integrate into
the PCB, but are less effective due to
difficult impedance matching because of
their very low radiation resistance.
For low power applications the λ/4-
monopole antenna is recommended giving
the best range and because of its
simplicity.
The length of the λ/4-monopole antenna is
given by:
where f is in MHz, giving the length in cm.
An antenna for 433.92 MHz should be
16.4 cm.
The antenna should be connected as
close as possible to the IC. If the antenna
is located away from the input pin the
antenna should be matched to the feeding
transmission line. See Application Note
AN003 “Antennas” for more details.
L = 7125 / f
®
CC400
Page 16 of 27