MRF24J40MD Datasheet, PDF (11/34 Pages) Microchip Technology – 2.4 GHz IEEE Std. 802.15.4™ RF Transceiver Module with PA/LNA

MRF24J40MD/ME
2.0 CIRCUIT DESCRIPTION
The MRF24J40MD/ME is a 2.4 GHz IEEE
Std. 802.15.4™ compliant surface mount module with
integrated crystal, internal voltage regulator, matching
circuitry, power amplifier, low noise amplifier with PCB
trace antenna (MRF24J40MD) and 50Ω external
antenna connector (MRF24J40ME).
The MRF24J40MD/ME module interfaces to many
popular Microchip PIC microcontrollers through a 4-wire
SPI Interface, interrupt, wake, reset, power and ground.
An example application schematic is illustrated in
Figure 2-4.
Serial communications and register definitions for the
MRF24J40MD/ME module are documented in the
“MRF24J40 Data Sheet” (DS39776). Refer to this data
sheet for specific serial interface protocol and register
definitions. Also, see Section 1.4 “Operation” for
specific register settings that are unique to the
MRF24J40MD/ME module.
2.1 PCB Antenna (MRF24J40MD)
The Printed Circuit Board (PCB) antenna is fabricated
on the top copper trace of the module PCB. The layers
below the antenna have no copper traces. The ground
and power planes under the components serve as a
counterpoise to the PCB antenna. Additional ground
plane on the host PCB will substantially enhance the
performance of the module. For best performance,
place the module on the host PCB following the recom-
mendations in Section 1.2 “Mounting Details”.
The PCB antenna was designed and simulated using
Ansoft Designer^® and HFSS™ 3D full-wave solver soft-
ware by Ansoft Corporation (www.ansoft.com) and
tested in an anechoic room. The design goal was to
create a compact, low-cost antenna with the best radi-
ation pattern. Figure 2-1 shows the simulation drawing
and Figure 2-2 and Figure 2-3 show the 2D and 3D
radiation patterns, respectively. As shown by the radia-
tion patterns, the performance of the antenna is depen-
dent upon the orientation of the module. The discrete
matching circuitry matches the impedance of the
antenna with the MRF24J40 transceiver IC.
FIGURE 2-1:
PCB ANTENNA SIMULATION DRAWING
 2014 Microchip Technology Inc.
Advance Information
DS70005173A-page 11