EM2420 ETC [List of Unclassifed Manufacturers], EM2420 Datasheet - Page 56

• Manufacturer Part Number: EM2420
• Description: 2.4 GHz IEEE 802.15.4 / ZigBee RF Transceiver
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Input / Output Matching
The RF input / output is differential (RF_N
and RF_P). In addition there is supply
switch output pin (TXRX_SWITCH) that
must have an external DC path to RF_N
and RF_P.
In RX mode the TXRX_SWITCH pin is at
ground and will bias the LNA. In TX mode
the TXRX_SWITCH pin is at supply rail
voltage and will properly bias the internal
PA.
Transmitter Test Modes
The EM2420 can be set into different
transmit test modes for performance
evaluation. The test mode descriptions in
the following sections require that the chip
is first reset, the crystal oscillator is
enabled using the SXOSCON command
strobe and that the crystal oscillator has
stabilized.
Unmodulated carrier
An
transmitted
MDMCTRL1.TX_MODE to 2, writing 0x1800
to the DACTST
STXON command strobe. The transmitter
is then enabled while the transmitter I/Q
DACs are overridden to static values. An
Ember Part Number: 120-0049-000C
unmodulated
register and issue a
by
carrier
may
setting
EM2420 Datasheet
be
The RF output and DC bias can be done
using different topologies. Some are
shown in Figure 3 and Figure 4.
Component values are given in Table 2.
Using a differential antenna, no balun is
required.
If a single ended output is required (for a
single ended connector or a single ended
antenna), a balun should be used for
optimum performance. The balun can be
realized using discrete inductors and
capacitors, or a LTCC balun can be used.
unmodulated carrier will then be available
on the RF output pins.
A plot of the single carrier output spectrum
from the EM2420 is shown in Figure 29
below.
EM2420
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