Note:
Ugo Raia
BlueNRG is a very low power Bluetooth low energy (BLE) single mode network processor, compliant with Bluetooth specifications.
Bluetooth low energy technology operates in the same spectrum range (2400 - 2483.5 MHz,
ISM band) as classical Bluetooth technology, but uses a different set of channels. Bluetooth low energy technology has 40 channels (37 data channels + 3 advertising channels) of 2
MHz band. Within the channel, data is transmitted using GFSK (Gaussian Frequency Shift
Modulation). The bit rate is 1 Mbit/s, and the maximum transmit power is 10 mW (10 dBm).
Further details are given in volume 6 part A of the Bluetooth Core Specification V4.0.
This application note outlines the expected performance when using the BlueNRG under
ETSI EN 300 328 in the 2400 to 2483.5 MHz band.
For details on the regulatory limits in 2400 - 2483.5 MHz frequency band, please, refer to
ETSI EN 300 328 V1.8.1 (2012-06).
These can be downloaded from www.etsi.org.
This application note content is valid for both BlueNRG and BlueNRG-MS devices. Any reference to a BlueNRG device is also valid for a BlueNRG-MS device. Any specific difference is highlighted wherever relevant.
April 2016 DocID025465 Rev 2 1/22 www.st.com
22

6
7
3
4
1
2
Contents
5
AN4387
An overview of ETSI regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Technical requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Transmitter parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1
RF output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2
Power spectral density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3
Occupied channel bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4
Transmitter unwanted emissions in out-of-band domain . . . . . . . . . . . . . 12
4.5
Transmitted unwanted emissions in spurious domain . . . . . . . . . . . . . . . 15
Receiver parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1
Receiver spurious emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2/22 DocID025465 Rev 2

AN4387
An overview of ETSI regulations
The use of radio equipment in most European countries is regulated through the R&TTE directive. The European Telecommunications Standard Institute (ETSI) is a standardization body that issues the standards for testing and type approval of transmitters and receivers.
EN 300 328 covers the 2.4 GHz band and specifies in detail the requirements and test methods to be used for license-free operated radio equipment under class 3a, equipment using wideband modulation techniques (DSSS or FHSS).
The standard defines two categories of equipment based on modulation type:
• Frequency Hopping Spread Spectrum (FHSS)
• Other types of wide band modulation (e.g. DSSS, OFDM, etc.)
It also covers both adaptive and non-adaptive equipment.
Adaptive equipment uses an automatic mechanism which allows the equipment to adapt automatically to its environment by identifying frequencies that are being used by other equipment.
ETSI classifies Bluetooth LE as adaptive equipment using DSSS modulation.
DocID025465 Rev 2 3/22
22

Technical requirements AN4387
4/22
The RF output power is defined as the mean equivalent isotropic radiated power (e.i.r.p.) of the equipment during a transmission burst.
The max allowed limit is -10 dBW (20 dBm, 100 mW).
It is the mean equivalent isotropically radiated power spectral density during a transmission burst.
Its value is limited to 10 dBm per MHz.
It is the bandwidth that contains 99% of the power of the signal.
It shall fall completely within the band 2.4 GHz to 2.4835 GHz.
They are emissions when the equipment is in transmit mode, on frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious.
The transmitter unwanted emissions in out-of-band domain but outside the allocated band,
shall not exceed the values provided by the mask in Table 1
.
Table 1. Transmitter in out-of-band domain
Frequency range Transmit mask level
< 2396 MHz
2396 to 2398 MHz
2398 to 2400 MHz
2400 to 2483.5 MHz
2483.5 to 2485.5 MHz
2485.5 to 2487.5 MHz
> 2487.5 MHz
- 20 dBm/MHz
- 10 dBm/MHz
-10 dBm/MHz
-20 dBm/MHz
Domain
Spurious
Out of Band
Out of Band
Allocated Band
Out of Band
Out of Band
Spurious
Transmitter unwanted emissions in spurious domain are emissions outside the allocated band and outside the out-of-band domain (as specified in previous table), when the equipment is in transmit mode.
The transmitter unwanted emissions in the spurious domain shall not exceed the values given in
Table 2
:
DocID025465 Rev 2

AN4387 Technical requirements
Frequency range
Table 2. Transmitter in spurious domain
Maximum power, e.r.p. ( ≤ 1 GHz) e.i.r.p. (> 1 GHz)
30 MHz to 47 MHz
47 MHz to 74 MHz
74 MHz to 87.5 MHz
87,5 MHz to 118 MHz
118 MHz to 174 MHz
174 MHz to 230 MHz
230 MHz to 470 MHz
470 MHz to 862 MHz
862 MHz to 1 GHz
1 GHz to 12.75 GHz
-36 dBm
-54 dBm
-36 dBm
-54 dBm
-36 dBm
-54 dBm
-36 dBm
-54 dBm
-36 dBm
-30 dBm
Bandwidth
100 kHz
100 kHz
100 kHz
100 kHz
100 kHz
100 kHz
100 kHz
100 kHz
100 kHz
1 MHz
Receiver spurious emissions are emissions at any frequency when the equipment is in receive mode. They shall not exceed the values given in
Table 3
:
Frequency range
30 MHz to 1 GHz
1 GHz to 12.75 GHz
Table 3. Receiver spurious emissions
Maximum power, e.r.p.
Measurement bandwidth
-57 dBm
-47 dBm
100 kHz
1 MHz
DocID025465 Rev 2 5/22
22

Application circuit AN4387
Figure 2 shows the BlueNRG application board photo. The application is constituted from 2
boards: a daughterboard and a motherboard. The daughterboard (see Figure 1
) holds the
BlueNRG with the circuits necessary for its works. The Bluetooth low energy protocol stack
(GAP, GATT, SM, L2CAP, LL, RF-PHY) is embedded on the device.
For the correctly functionality, the daughterboard have to be plugged on a motherboard (see
Figure 2 ) by two header 5 x 2 connectors (J6 and J7).
The motherboard is provided with a STM32L152VBT6 microcontroller to correctly program the transceiver. The micro is programmed with a firmware developed for BlueNRG application. A graphical user interface (GUI) is developed to program correctly the
BlueNRG.
The daughterboard is provided with a 16 MHz XTAL to provide the correct oscillator to the
BlueNRG. Also a low speed crystal oscillator is mounted on the board and used from
BlueNRG.
An internal SMPS is present on the BlueNRG to drastically reduce the power consumption.
The SMPS is fed from the battery and provide to device a programmable voltage (1.4 V usually).
An SMA connector is present to connect the board to an antenna or to an instrument to verify correct functioning and to verify standard compliance.
A few of passive (inductors and capacitors) are used as matching/filtering for the power amplifier (PA) and balun network for the receiver.
Figure 1. BlueNRG application daughterboard
$0Y
6/22 DocID025465 Rev 2

AN4387 Application circuit
Figure 2. : BlueNRG application daughterboard plugged into motherboard
$0Y
DocID025465 Rev 2 7/22
22

Figure 3. Daughterboard schematic
JTMS
JTCK
JTDO
JTDI
3V3 nS
2
VDD
1
1
U2
2
Jumper2
J3
HEADER 5X2
R7
100k_0402 nS
MISO
R3 nc
R4 nc
R5 nc
R6 nc
Male Connector 2x5
J1
8
10
2
4
6
1
3
5
7
9
JTAG
1
2
3
4
U3 nS
Q nW
Vss
M95640
Vcc nHOLD
C
D
8
7
6
5
CLK
MOSI
3V3
VDD
J4
HEADER 5X2
C3
100p_0402_COG
C1
1u_0402_X5R
C4
150n_0402_X5R
C2
100n_0402_X7R
D1
1 3
Solder a 10u_0805 between 1-2 or a 0R0_0805 between 1-3
VDD
C5
22p_0402_COG
Q1
C6
22p_0402_COG
U1
MOSI
CLK
IRQ
VBAT3
JTCK
3
4
1
2
5
6
7
8
SPI_MOSI
SPI_CLK
DIO7
DIO6
VBAT3
DIO5
DIO4
JTAG_TCK
BlueNRG-N
VBAT1
SXTAL0
SXTAL1
RF0
RF1
VBAT2
FXTAL0
FXTAL1
24
23
22
21
20
19
18
17
VBAT2
XTAL_32k
C7
TBD_0402_COG
L1
TBD_0402
C8
C9 TBD_0402_COG
TBD_0402_COG
L3
L2
TBD_0402
TBD_0402
C11
TBD_0402_COG
VDD
R1 nc
C10
R2
10k_0402
TBD_0402_COG
C12
TBD_0402_COG
J2
SMA laterale
Q2
12p_0402_COG
C13
C14
12p_0402_COG
XTAL_16M
C15
100p_0402_COG
C17
1u_0402_X5R
VDD
VBAT1
C18
100n_0402_X7R
C16
100n_0402_X7R
SOSCOUT
AUXADP
AUXADN
SOSCOUT
AUXADP
AUXADN
FTEST
1 3
JP1
FTEST VDD
R9
C19
100n_0402_X7R
100k_0402
C20
1u_0402_X5R
VDD
VBAT2
C21
100n_0402_X7R
C22
1u_0402_X5R
VDD
VBAT3
C23
100n_0402_X7R
AM17653v1

AN4387 Transmitter parameter
All the measurement here reported are measured with the following parameters: T
C
V dd specified.
= 25 °C,
= 3.3 V, f = 2402 MHz (lower frequency of the useful bandwidth), unless otherwise
9
8
7
6
5
4
3
2
1
0
-1
2400
The measurements performed at the lowest, the middle, and the highest channel show results lower than the maximum permitted output power:
Frequency (MHz)
2402
2442
2480
Table 4. RF output power
Channel
37
18
39
Output power
7.5 dBm
7.5 dBm
7.4 dBm
Figure 4. RF output power Ch 37
AM17654v1
2400.5
2401 2401.5
2402
MHz
2402.5
2403 2403.5
2404
The measurement shall be performed at the lowest, the middle, and the highest channel on which the equipment can operate.
The transmitter shall be connected to a spectrum analyzer with the following settings:
Start Freq: 2400 MHz; Stop Freq: 2483.5 MHz; Res BW: 10 kHz; Video BW: 30 kHz
Sweep Points: > 8350; Detector: RMS; Trace Mode: Max Hold; Sweep time: Auto
DocID025465 Rev 2 9/22
22

Transmitter parameter
The measures show a value in line with the limit: 10 dBm/MHz.
Figure 5. Power spectral density Ch 37
10
0
-10
-20
-30
-40
-50
-60
2401 2401.5
2402
MHz
2402.5
AN4387
AM17655v1
2403
The measurement shall be performed at the lowest and the highest frequency within the stated frequency range.
The spectrum analyzer must be set with:
Center Freq: The center freq of the channel under test; Res BW: ~1% of the span without going below 1%; Video BW: 3 × RBW; Freq Span: 4 MHz; Detector Mode: RMS;
Trace Mode: Max Hold.
Find the peak value of the trace and place the analyzer marker on this peak.
Use the 99 % bandwidth function of the spectrum analyzer to measure the occupied channel bandwidth of the UUT.
The measures show a value equal to 1 MHz for all channels; it fall completely within the band 2.4 - 2.4835 GHz.
10/22 DocID025465 Rev 2

AN4387 Transmitter parameter
Figure 6. Occupied channel bandwidth Ch 37
10
0
-10
-20
-30
AM17656v1
-40
-50
2400 2400.5
2401 2401.5
2402
MHz
2402.5
2403 2403.5
2404
DocID025465 Rev 2 11/22
22

Transmitter parameter
AN4387
The measurement shall be performed at the lowest and the highest channel on which the equipment can operate.
The spectrum analyzer must be set with:
Centre Frequency: 2484 MHz; Span: 0 Hz; Resolution BW: 1 MHz
Filter mode: Channel filter; Video BW: 3 MHz; Detector Mode: RMS
Trace Mode: Clear/Write; Sweep Mode: Continuous; Sweep Points: 5000
Trigger Mode: Video trigger; Sweep Time: Suitable to capture one transmission burst
For the segment 2483.5 MHz to 2485.5 MHz:
– Adjust the trigger level to select the transmissions with the highest power level.
– Set a window (start and stop lines) to match with the start and end of the burst and in which the RMS power shall be measured using the time domain power function.
– Select RMS power to be measured within the selected window and note the result which is the RMS power within this 1 MHz segment (2483.5 MHz to 2484.5 MHz).
– Compare this value with the applicable limit provided by the mask.
– Increase the center frequency in steps of 1 MHz and repeat this measurement for every 1 MHz segment within the range 2483.5 MHz to 2485.5 MHz. The center frequency of the last 1 MHz segment shall be set to 2485.5 MHz - 0.5 MHz (which means this may partly overlap with the previous 1 MHz segment).
For the segment 2485.5 MHz to 2487.5 MHz:
Change the center frequency of the analyzer to 2486 MHz and perform the measurement for the first 1 MHz segment within range 2485.5 MHz to 2487.5 MHz. Increase the center frequency in 1 MHz steps and repeat the measurements to cover this whole range.
The center frequency of the last 1 MHz segment shall be set to 2487.5 MHz - 0.5 MHz.
For the segment 2398 MHz to 2400 MHz:
Change the center frequency of the analyzer to 2399.5 MHz and perform the measurement for the first 1 MHz segment within range 2398 MHz to 2400 MHz.
Reduce the center frequency in 1 MHz steps and repeat the measurements to cover this whole range.
The center frequency of the last 1 MHz segment shall be set to 2396 MHz + 0.5 MHz.
For the segment 2396 MHz to 2398 MHz:
Change the center frequency of the analyzer to 2397.5 MHz and perform the measurement for the first 1 MHz segment within range 2396 MHz to 2398 MHz. Reduce the center frequency in 1 MHz steps and repeat the measurements to cover this whole range.
The center frequency of the last 1 MHz segment shall be set to 2396 MHz + 0.5 MHz.
A prescan analysis in the range below 2.4 GHz (
Figure 7 ) permits to search for unwanted
spurious: no particular emissions were found.
12/22 DocID025465 Rev 2

AN4387 Transmitter parameter
Figure 7. Prescan of emissions in the out-of-band domain below 2400 MHz
0 AM17657v1
-10
-20
-30
-40
-50
-60
-70
10 510 1010 1510 2010
MHz
Follows the detailed analysis in all the ranges specified by the mask; the BlueNRG meets the requirement with large margin.
0
Figure 8. Emissions in the out-of-band domain for the range 2396-2398 MHz
AM17658v1
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
2397 2397.2
2397.4
2397.6
2397.8
2398
MHz
DocID025465 Rev 2 13/22
22

Transmitter parameter AN4387
-5
-10
-15
-20
-25
-30
-35
0
Figure 9. Emissions in the out-of-band domain for the range 2398 - 2400 MHz
AM17659v1
-40
2399 2399.2
2399.4
2399.6
2399.8
2400
MHz
Figure 10. Emissions in the out-of-band domain for the range 2483.5 - 2485.5 MHz
0
AM17660v1
-10
-20
-30
-40
-50
-60
2483.5
2483.7
2483.9
MHz
2484.1
2484.3
2484.5
14/22 DocID025465 Rev 2

AN4387 Transmitter parameter
Figure 11. Emissions in the out-of-band domain for the range 2485.5 - 2487.5 MHz
0
AM17661v1
-10
-20
-30
-40
-50
-60
2485.5
2485.7
2485.9
MHz
2486.1
2486.3
2486.5
The measurement shall be performed at the lowest and the highest channel on which the equipment can operate.
To identify potential unwanted emissions the spectrum analyzer settings are:
For the range 30 MHz to 1000 MHz:
Resolution bandwidth: 100 kHz; Video bandwidth: 300 kHz; Detector mode: Peak
Trace Mode: Max Hold; Sweep Points: ≥ 9970
For the range 1 GHz to 12.75 GHz:
Resolution bandwidth: 1 MHz; Video bandwidth: 3 MHz; Detector mode: Peak
Trace Mode: Max Hold; Sweep Points: ≥ 11750
Instead, to accurately measure the individual unwanted emissions:
Centre Frequency: Frequency of emission identified during the prescan;
Resolution Bandwidth: 100 kHz (< 1 GHz) / 1 MHz (> 1 GHz)
Video Bandwidth: 300 kHz (< 1 GHz) / 3 MHz (> 1 GHz)
Frequency Span: Wide enough to capture each individual emission identified during the prescan
Sweep mode: Continuous
Sweep time: Auto
Trigger: Free run
DocID025465 Rev 2 15/22
22

Transmitter parameter AN4387
Detector: RMS
Trace Mode: Max Hold
The BlueNRG passes the test without problems
Figure 12. Transmitted emissions in the spurious domain, range 30-1000 MHz
-10
AM17662v1
-20
-30
-40
-50
-60
-70
-80
30 130 230 330 430 530
MHz
630 730 830 930
16/22 DocID025465 Rev 2

AN4387
-30
-40
-50
-10
-20
-60
2487.5
Transmitter parameter
Figure 13. Transmitted emissions in the spurious domain, range 2.3 - 2.396 GHz
AM17663v1
0
-10
-20
-30
-40
-50
-60
-70
2300 2320 2340 2360 2380
MHz
Figure 14. Transmitted emissions in spurious domain, range 2.4875 - 12.75 GHz
0
AM17664v1
4487.5
6487.5
MHz
8487.5
10487.5
12487.5
DocID025465 Rev 2 17/22
22

Receiver parameter AN4387
The measurement shall be performed at the lowest and the highest channel on which the equipment can operate.
Testing shall be performed when the equipment is in a receive-only mode.
The spectrum analyzer settings are equivalent to those used for the transmitted unwanted emissions in spurious domain. No particular troubles were registered for this test.
Figure 15. Receiver spurious emissions, range 30 - 1000 MHz
AM17665v1
-30
-40
-50
-60
-70
-80
-90
-100
30 230 430
MHz
630 830
18/22 DocID025465 Rev 2

AN4387
-70
-80
-90
-100
1000
-40
-50
-60
-30
Receiver parameter
Figure 16. Receiver spurious emissions, range 1 - 12.75 GHz
AM17666v1
3000 5000 7000
MHz
9000 11000
DocID025465 Rev 2 19/22
22

Reference
AN4387
[1] BlueNRG Datasheet
[2] ETSI EN 300 328 V1.8.1 (2012-06)
[3] "Bluetooth Low Energy Regulatory Aspects", from Bluetooth SIG Regulatory Committee
20/22 DocID025465 Rev 2

AN4387 Revision history
Date
14-Nov-2013
07-Apr-2016
Table 5. Document revision history
Revision Changes
1
2
Initial release.
Updated document title by adding “BlueNRG-MS”
Introduction
: updated text and added a note
Section 3: Application circuit : updated text and removed
2.0 V to 3.6 V.
DocID025465 Rev 2 21/22
22

AN4387
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Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
© 2016 STMicroelectronics – All rights reserved
22/22 DocID025465 Rev 2