Renesas RX23W Series Installation and operating instructions

Application Note
R01AN4534EJ0201 Rev.2.01 Page 1 of 52
Sep.30.21
RX23W Group
Guidelines for Bluetooth Board Design
Introduction
This document describes RF board design guidelines for RX23W Bluetooth®5.0 (Core Specification v5.0)
RF transceiver. Please refer "RX Family Hardware Design Guide for board design" (R01AN1411) except
Bluetooth 5.0 RF transceiver part.
Target Device
RX23W Group
Note: The contents of this document are provided as a reference and do not guarantee the signal quality in
the system. When designing the actual system, thoroughly evaluate the product in the overall system
and apply these contents on your own responsibility.
Contents
1. Overview.................................................................................................................................... 3
1.1 Related documents ................................................................................................................................. 3
2. Board design guidelines for RX23W QFN ................................................................................. 4
2.1 RX23W QFN Pin list................................................................................................................................ 4
2.2 Oscillator circuit for Bluetooth-dedicated clock ....................................................................................... 5
2.3 Antenna connection pin........................................................................................................................... 8
2.4 Power supply mode for Bluetooth 5.0 RF transceiver........................................................................... 12
2.4.1 DC-DC converter mode....................................................................................................................... 12
2.4.2 Linear regulator mode ......................................................................................................................... 15
2.5 Power supply and ground patterns........................................................................................................ 17
2.5.1 Power supply....................................................................................................................................... 17
2.5.2 Ground................................................................................................................................................. 18
2.6 Circuit diagram for reference................................................................................................................. 20
2.7 Parts list for reference ........................................................................................................................... 21
3. Board design guidelines for RX23W BGA ............................................................................... 22
3.1 RX23W BGA Pin list.............................................................................................................................. 22
3.2 Oscillator circuit for Bluetooth-dedicated clock ..................................................................................... 23
3.3 Antenna connection pin......................................................................................................................... 26
3.4 Power supply mode for Bluetooth 5.0 RF transceiver........................................................................... 30
3.4.1 DC-DC converter mode....................................................................................................................... 30
3.4.2 Linear regulator mode ......................................................................................................................... 33
3.5 Power supply and ground patterns........................................................................................................ 35
3.5.1 Power supply....................................................................................................................................... 35

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3.5.2 Ground................................................................................................................................................. 36
3.6 Circuit diagram for reference................................................................................................................. 38
3.7 Parts list for reference ........................................................................................................................... 39
4. Board design guidelines for RX23W LGA ............................................................................... 40
4.1 RX23W LGA Pin list .............................................................................................................................. 41
4.2 Oscillator circuit for Bluetooth-dedicated clock ..................................................................................... 43
4.3 Antenna connection pin......................................................................................................................... 43
4.4 Power supply mode for Bluetooth 5.0 RF transceiver........................................................................... 44
4.5 Ground................................................................................................................................................... 44
4.6 Antenna layout....................................................................................................................................... 46
4.7 Main Board Design................................................................................................................................ 48
4.8 Emission characteristics........................................................................................................................ 49
4.9 Housing Design ..................................................................................................................................... 50
4.10 Foot pattern design example................................................................................................................. 51
Revision History .............................................................................................................................. 52
The Bluetooth®word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of
such marks by Renesas Electronics Corporation is under license. Other trademarks and registered
trademarks are the property of their respective owners.

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Sep.30.21
1. Overview
Sections 2, 3, and 4 of this document describe board design guidelines for RX23W QFN package, RX23W
BGA package, and RX23W LGA package, respectively. This document briefly describes the Bluetooth 5.0
RF transceiver unit pins used in the RX23W.
1.1 Related documents
The following documents are related to this application note. Also refer to these documents when using this
application note.
•RX23W group User’s Manual: Hardware (R01UH0823)
•RX Family Hardware Design Guide (R01AN1411)
•RX23W group Tuning procedure of Bluetooth dedicated clock frequency (R01AN4762)

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2. Board design guidelines for RX23W QFN
2.1 RX23W QFN Pin list
Table 2-1 is the description of Bluetooth 5.0 RF transceiver unit pins in RX23W QFN.
Table 2-1 Description of Bluetooth 5.0 RF transceiver unit pins in RX23W QFN
Pin Number
Pin Name
I/O
Functions
48 CLKOUT_RF Output
Bluetooth-Dedicated clock output pin, whose frequency can be set to 4,
2, or 1MHz. The default output setting is off. Connecting the clock
output pin to the external clock input pin of MCU, the RF clock can be
used as the MCU system clock.
32 ANT In/Out
RF single I/O pin for RF transceiver.
Adjust the characteristic impedance of the signal line to 50ohm.
38 XTAL1_RF Input
Pins for connecting the Bluetooth-dedicated clock oscillator. 32-MHz
oscillator connection pin
37 XTAL2_RF Output
Pins for connecting the Bluetooth-dedicated clock oscillator. 32-MHz
oscillator connection pin
40 DCLOUT
Output
RF transceiver power-supply (DC-DC converter or linear regulator) output pin
46 DCLIN_A Input
RF transceiver power-supply output connection pin. This pin should be
connected to an external inductor and capacitor when the DC-DC
converter mode is selected. When the linear regulator mode is selected,
this pin should be connected to an external capacitor.
45 DCLIN_D Input
RF transceiver power-supply output connection pin. This pin should be
connected to an external inductor and capacitor when the DC-DC
converter mode is selected. When the linear regulator mode is selected,
this pin should be connected to an external capacitor.
44 VCC_RF
Input
RF transceiver power supply pin
39 AVCC_RF
Input
RF transceiver power supply pin
28 ICGND
(VSS_RF)
Input
RF transceiver ground pin.
In this document, this pin is called “ICGND”.
Exposed Die
Pad VSS_RF Input RF transceiver ground pin

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2.2 Oscillator circuit for Bluetooth-dedicated clock
Note the following when designing an oscillator circuit for Bluetooth-dedicated clock.
•Place the crystal resonator close to the “XTAL1_RF” and “XTAL2_RF” pins. We recommend the wiring
length between the RX23W and the crystal resonator of approximately 6 mm, as shown in "Figure 2-2
Example of the pattern around the crystal resonator".
•Shield the pattern for the “XTAL1_RF” and “XTAL2_RF” pins with the ground pattern. Do not place the
pattern for these signals in parallel with or across other patterns where a large current flows or the level
changes frequently.
•Not place any signal, power, and ground lines except the oscillator circuit’s on and below the oscillator
circuit area. We recommend that the ground pattern is placed in the layers under the oscillator circuit, as
shown in "Figure 2-2 Example of the pattern around the crystal resonator".
•Separate the oscillator circuit and the signal line from an antenna to “ANT” pin by placing slit patterns on
all layers.
•Ensure a return path in layer2 (additional layer3 if possible) from ground of the crystal resonator to
"Exposed Die Pad (VSS_RF)”, as shown in "Figure 2-2 Example of the pattern around the crystal
resonator".
•External load capacitors (CL) for frequency tuning are unnecessary, because the capacitors are built in
IC. For Tuning procedure of Bluetooth dedicated clock frequency, see the descriptions of the application
note, the Hardware Design Guide(R01AN4762). The latest version can be downloaded from the Renesas
Electronics website.
•Insert a damping resistor (Rd) as required. Set the resistance to the value recommended by the oscillator
manufacturer as the value depends on the oscillator and its driving capability. If the oscillator
manufacturer states that the addition of a feedback resistor (Rf) to the oscillator is required, insert Rf
between XTAL1_RF and XTAL2_RF according to the instructions.
•When the frequency-divided clock for the Bluetooth-dedicated clock is output, note designing board
pattern. The wiring length should be as short as possible. In addition, must not branch the wiring. And
avoid using vias on the transmission line. A maximum of 2 is recommended.
•Shield the transmission line of CLKOUT_RF with the "VSS" pattern to avoid noise couplings to
“VSS_RF”.
Note: Bluetooth 5.0 RF transceiver clock frequency accuracy which includes initial error, temperature drift,
and ageing effect should be less than or equal to +/-50ppm in the Bluetooth specification. Therefore,
the frequency error should be as less as possible.
Figure 2-1 shows an example of the crystal resonator connection. Figure 2-2 shows an example of the
pattern around the crystal resonator.

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Note: The resistance of Rd and Rf should be determined thorough oscillation characteristics evaluation with
a crystal resonator to be mounted. These resistors might not be required, depending on the oscillation
characteristics.
Figure 2-1 Example of the crystal resonator connection.
Figure 2-2 Example of the pattern around the crystal resonator
XTAL2_RF
XTAL1_RF
Rd
X1
VSS_RF
Rf

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Table 2-2 shows confirmed operation crystal resonator list (reference).
Table 2-2 Tested crystal resonator list (reference)
Manufacturer Parts number
SMD/Lead
size code
(in mm)
Frequency
(MHz)
Frequency
Tolerance
(ppm)
Frequency
Stability
(ppm)
Equivalent
Series
Resistance
(ohm)
Load
Capacitance
(pF)
NDK NX1612SA-32.000MHZ-
CHP-CIS-3 1612 32.00 +/-10 +/-20 Max 100 6
NDK NX1210AB- 32.000MHZ-
CHP-CIX-3 1210 32.00 Total +/-30 Max 100 6
Kyocera CX1612DB32000
A0WPNC1 1612 32.00 Total +/-25 Max 100 5
Kyocera CX1210SB32000
B0GPJC1 1210 32.00 Total +/-30 Max 80 6
Murata XRCMD32M000FZQ52R0 1612 32.00 Total +/-30 Max 60 6
Murata XRCTD32M000N1P00R0 1210 32.00 Total +/-30 Max 120 6

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2.3 Antenna connection pin
Note the followings for antenna connection pin design.
•Adjust the characteristic impedance of 50ohm for the signal line from an antenna to “ANT” pin. Optimize
the width of signal line and the gap between signal line and ground pattern, considering the PCB
permittivity and layer thickness. Depending on the antenna used, additional parts such as inductors or
capacitors may be required. In "Figure 2-3 Example of the pattern around “ANT” pin", the coplanar
waveguide is used.
•When mounting a connector, keep the characteristic impedance of 50ohm including the connector.
•The directly under layer of the coplanar waveguide should be solid ground, having no crossing with any
signal, power, and other ground lines.
•Place vias as many as possible between the coplanar waveguide ground pattern and the solid ground.
We recommend that the via spacing should be approximately 0.9mm, as shown in "Figure 2-3 Example
of the pattern around “ANT” pin".
Figure 2-3 shows an example of the pattern around “ANT” pin.
Figure 2-3 Example of the pattern around “ANT” pin

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•Pay attention to an emission level of 5th order harmonics, when selecting 4 dBm transmitted output mode
and evaluating of US(FCC) regulatory with a coaxial cable. The emission should be suppressed with an
RF filter implementation.
RF filter requirements
Frequency band to be suppressed: 12.01 to 12.4 GHz
Minimum attenuation: 8dB
•Pay attention to an emission level of 3rd order harmonics, when selecting 0 dBm transmitted output mode
and evaluating of US(FCC) regulatory with a coaxial cable. The emission should be suppressed with an
RF filter implementation.
RF filter requirements
Frequency band to be suppressed: 7250 to 7440 MHz
Minimum attenuation: 2dB
This document describes an example of an open circuit stub and an example of LPF using SMD parts. Both
of these circuits can suppress 5th order harmonics of 4 dBm transmitted output mode and the 3rd order
harmonics of 0 dBm transmitted output mode.
Figure 2-4 shows an example of the open circuit stub.
Figure 2-4 Example of the open circuit stub
Note: The pattern width and pattern pitch for impedance control vary depending on board thickness,
material, and layer configuration. Contact the board manufacturer for more information.
Obtain an effective permittivity ɛ
r,eff
from the above board
composition.
effective permittivity ɛr,eff ≒3.515
The wavelength of 12400MHz is approximately 24.18 mm.
Then calculate the length of a stub by using the formula
below.
the length of a stub L= 0.25*λ / (ɛr,eff)0.5 = 3.224mm
Permittivity(ɛ
r
)=4.45
S=0.41mm
W=0.72mm
h=0.2mm
Frequency=12400MHz (2480MHz x 5)
Note: Place the open circuit stub as close to “ANT” pin as
possible. We recommend that it should place
approximately 3.5mm, as shown in example pattern
on the right figure.

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Figure 2-5 shows an example of LPF using SMD parts
Figure 2-5 Example of LPF using SMD parts
Note: Depending on the PCB design, the value may differ. Adjust the value, if necessary.
ANT
L201
C201
C201 = GJM1555C1HR20WB01 (0.2pF +/-0.05pF)
L201 = LQG15HS1N5S02 (1.5nH +/-0.3nH)

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•When certifying of Korea (KCC) regulatory, an emission of 1.9GHz frequency band should be suppressed
with an RF filter implementation.
RF filter requirements
Frequency band to be suppressed: 1921 to 1984 MHz
Minimum attenuation: 7dB
This document describes an example of a notch filter. Figure 2-6 shows an example of the notch filter.
RF filter requirements
Frequency band to be suppressed : 1921 to 1984 MHz
Minimum attenuation : 7dB
Note: Depending on the PCB design, the value of capacitor C101 may differ.
Adjust the value of capacitor C101, if necessary.
Figure 2-6 Example of the notch filter
ANT
L101
C101
L101 = LQG15HS7N5J02 (7.5nH +/-5%)
C101 = GCM1555C1HR50BA16 (0.5pF +/-0.1pF)

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2.4 Power supply mode for Bluetooth 5.0 RF transceiver
Note the followings for external circuit design in each power supply mode of the Bluetooth 5.0 RF
transceiver. User should select the power mode for Bluetooth 5.0 RF transceiver which DC-DC converter
mode or Linear regulator mode.
When the DC-DC converter mode is selected, inductors on PCB are required. However, the BLE operating
current reduction is conferred. On the other hand, When the Linear regulator mode is selected, BLE
operating current increases more than DC-DC converter mode. However, the BoM cost and Board area can
be reduced because mounting inductors for DC-DC converter mode is unnecessary.
2.4.1 DC-DC converter mode
Note the followings in external circuit design for the DC-DC converter mode.
•Design the signal pattern from “DCLOUT” pin to “VSS_RF” through an inductor “L1” and a capacitor “C1”
shorter and wider for low impedance connection. Place ground pattern in area which is enclosed with line
connecting “DCLOUT” and “DCLIN_A”, as shown in "Figure 2-8 Example of the PCB pattern for DC-DC
converter mode". In addition, connect a capacitor “C1” and “VSS_RF” to this ground pattern.
•Connect the line connecting “DCLOUT” and “DCLIN_A” on parts surface of the board through no the via.
•Reduce loop area which is enclosed with line connecting “DCLOUT” and “DCLIN_A” as small as possible.
•Placing the inductor “L1” and capacitor as close as possible to the “DCLOUT” pin is recommended.
•Not place other SMD parts except the external circuit for DC-DC converter mode, on the loop which is
enclosed with line connecting “DCLOUT” and “DCLIN_A”.
•Ensure a return path in layer2 (additional layer3 if possible) from ground in the loop to "Exposed Die Pad
(VSS_RF)”, as shown in "Figure 2-8 Example of the PCB pattern for DC-DC converter mode".
•Recommended electrical characteristics of “L1” is follows;
Inductance=10uH +/-20%
Rated current (min)=90mA
DC resistance(max)=1.0ohm
Self resonant frequency(min)= 30MHz.
Less power loss and good DC superimposing
•“C2” capacitance should be less than or equal to 2.2uF +/-20%.
•Not place any analog signal, power, and ground lines except the external circuit for DC-DC converter
mode, on and below the circuit area.
•With mounting an inductor “L2”, noise caused by the DC-DC converter can be reduced. Therefore, it is
recommended to prepare inductor L2 mount space on a board pattern.

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Figure 2-7 shows an example of the external circuit for DC-DC converter mode, Figure 2-8 shows an
example of the PCB pattern.
Figure 2-7 Example of the external circuit for DC-DC converter mode
DCLIN_D
VSS_RF
L1
L1 = 10uH
L2 = short (reserved inductor)
C1 = 2.2uF
C2 = 2.2uF
DCLOUT
C1
DCLIN_A
VCC_RF
C2
L2

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Figure 2-8 Example of the PCB pattern for DC-DC converter mode

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2.4.2 Linear regulator mode
Note the followings in external circuit design for the Linear regulator mode.
•Make the signal pattern from “DCLOUT” pin to “VSS_RF” through “C1” shorter and wider for low
impedance connection. Place ground pattern in area which is enclosed with line connecting “DCLOUT”
and “DCLIN_A”, as shown in "Figure 2-10 Example of the PCB pattern for Linear regulator mode". In
addition, connect a capacitor “C1” and “VSS_RF” to this ground pattern.
•Connect the line connecting “DCLOUT” and “DCLIN_A” on parts surface of the board through no the via.
•Reduce loop area which is enclosed with line connecting “DCLOUT” and “DCLIN_A” as small as possible.
•Not place other SMD parts except the external circuit for Linear regulator mode, on the loop which is
enclosed with line connecting “DCLOUT” and “DCLIN_A”.
•Ensure a return path in layer2 (additional layer3 if possible) from ground in the loop to "Exposed Die Pad
(VSS_RF)”, as shown in "Figure 2-10 Example of the PCB pattern for Linear regulator mode".
•Not place any analog signal, power, and ground lines except the external circuit for Linear regulator, on
and below the circuit area.
•“C2” capacitance should be less than or equal to 0.47uF +/-20%.
Figure 2-9 shows an example of the external circuit for Linear regulator mode, Figure 2-10 shows an
example of the PCB pattern.
Figure 2-9 Example of the external circuit for Linear regulator mode
DCLIN_D
VSS_RF
C1 = 0.47uF
C2 = 2.2uF
DCLOUT
C1
DCLIN_A
VCC_RF
C2

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Figure 2-10 Example of the PCB pattern for Linear regulator mode

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2.5 Power supply and ground patterns
Note the followings for power supply patterns and ground patterns design.
2.5.1 Power supply
Note the followings for power supply patterns design.
•Not bring other power, and ground lines close up “AVCC_RF” and “VCC_RF” to avoid noise couplings.
•Connect power supply patterns “VCC_RF”, “AVCC_RF”, and other power supply “VCC” with single point
short. And separate power supply patterns “VCC_RF”, “AVCC_RF”, and “VCC” each other.
•Make the power supply patterns of “VCC_RF” and “AVCC_RF” low impedance.
•Place bypass capacitors of “VCC_RF” and “AVCC_RF” nearby IC pin.
•Not place one or more vias on a connection between a bypass capacitor and “VCC_RF” or “AVCC_RF”
pin.
Figure 2-11 shows an example of how to place the bypass capacitors.
Note: Noise varies depending on the board mounting. Add bypass capacitors as required.
Figure 2-11 Example of bypass capacitor connection
C2
VCC_RF
C3
AVCC_RF
VSS_RF
Power Supply
C2 = 2.2uF
C3 = 0.1uF

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2.5.2 Ground
Note the followings for ground patterns design.
•Design a ground pattern to be as wide plane as possible.
•When using ground pattern as the shield line, place away from the oscillation circuit and the digital circuit
as much as possible not to give noise the shield line.
•Back pad of IC Package (Exposed Die Pad) is a Bluetooth 5.0 RF transceiver reference ground. Not pass
other power, and ground lines through the reference ground to avoid noise effects. And not separate the
reference ground pattern.
•Under layer of IC Package should be “VSS_RF” solid ground. Make the ground patterns of “VSS_RF” low
impedance. It is recommended to place vias as shown in "Figure 2-12 Example of the ground pattern".
•Not bring other power and ground lines close up “VSS_RF” to avoid noise couplings.
•When connecting the ground pattern to other layer of same potential, the connection should be low
impedance with many vias.
•Connect “VSS_RF” and other grounds which are “VSS”, “AVSS0”, and “VSS_USB”, with single point
short.
•Separate “ICGND” pin and "Exposed Die Pad (VSS_RF)” on the surface layer of the board.

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Figure 2-12 shows an example of the ground pattern.
Figure 2-12 Example of the ground pattern

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2.6 Circuit diagram for reference
Figure 2-13 shows a reference circuit diagram in which the Bluetooth 5.0 RF transceiver related part is only
described.
Figure 2-13 Circuit diagram (for reference)