Infineon BGT60ATR24C Installation and operating instructions

Application note
Please read the sections “Important notice” and “Warnings” at the end of this document
Revision 1.10
www.infineon.com
2023-02-14
AN620
BGT60ATR24C ES shield
XENSIV™60 GHz radar system platform
B o a r d v e r s i o n V 2 . 0
About this document
Scope and purpose
This application note describes the function, circuitry, and performance of the BGT60ATR24C shield
(SHIELD_60ATR24ES_01) , part of Infineon’s XENSIV™ 60 GHz radar system platform. The shield provides the
supporting circuitry to the on-board BGT60ATR24C monolithic microwave integrated circuit (MMIC) Infineon’s
60 GHz radar chipset with external antennas. The shield offers a digital interface for configuration and transfer
of the acquired radar data to a microcontroller board, e.g., Radar Baseboard MCU7.
The MMIC-related parameters mentioned in the document are based on engineering samples (ES).
Intended audience
The intended audience for this document are design engineers, technicians, and developers of electronic
systems, working with Infineon’s XENSIV™ 60 GHz radar sensors, especially in automotive scenarios called in-
cabin sensing (ICMS). Among the many applications it can be used for are–rear occupancy alert (ROA) and –left
behind child (LBC) systems.
Related documents
Additional information can be found in the documentation provided with the Radar Development Kit tool in the
Infineon Developer Center (IDC), or from www.infineon.com/60GHz.

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BGT60ATR24C ES shield
XENSIV™60 GHz radar system platform
Table of contents
Table of contents
About this document....................................................................................................................... 1
Table of contents............................................................................................................................ 2
1Introduction .......................................................................................................................... 3
1.1 60 GHz radar system platform ................................................................................................................3
1.2 Key features.............................................................................................................................................3
2System specifications............................................................................................................. 4
2.1 Typical power consumption ...................................................................................................................4
3Hardware description............................................................................................................. 5
3.1 Overview..................................................................................................................................................5
3.2 Sensor supply..........................................................................................................................................5
3.3 Oscillator..................................................................................................................................................6
3.4 Connectors ..............................................................................................................................................7
3.5 EEPROM ...................................................................................................................................................7
3.6 Layer stackup ..........................................................................................................................................8
3.7 Metal layers overview..............................................................................................................................8
4Layout overview ...................................................................................................................10
4.1 Component side ....................................................................................................................................10
4.2 Antenna side..........................................................................................................................................10
5TX and Rx channels................................................................................................................12
5.1 Phase relationship between RF channels ............................................................................................12
5.1.1 TX outputs ........................................................................................................................................12
5.1.2 RX channels ......................................................................................................................................12
6Measurement results.............................................................................................................13
6.1 Transmitter and receiver antenna matching .......................................................................................13
6.2 System radiation characteristics..........................................................................................................14
References....................................................................................................................................19
Revision history.............................................................................................................................20
Disclaimer.....................................................................................................................................21

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BGT60ATR24C ES shield
XENSIV™60 GHz radar system platform
Introduction
1Introduction
1.1 60 GHz radar system platform
The 60 GHz radar system platform is the demo platform for Infineon’s 60 GHz radar solutions. It consists of the
Radar Baseboard MCU7 as the microcontroller board and a radar sensor board, like the BGT60ATR24C shield for
Infineon’s 60 GHz radar sensor chip. This application note focuses on the BGT60ATR24C shield. Detailed
information about the Radar Baseboard MCU7 can be found in the corresponding application note [1].
Figure 1 illustrates the Radar Baseboard MCU7 with the BGT60ATR24C shield. The shield has to be plugged into
the longer connectors on the baseboard’s bottom side with an orientation as shown below.
a)
Sensor board (antenna side) b) Radar Baseboard MCU7 (bottom side)
Figure 1 Radar Baseboard MCU7 with the BGT60ATR24C shield
1.2 Key features
The BGT60ATR24C shield is designed to showcase the capabilities of the BGT60ATR24C. This device offers
customers design flexibility in terms of their desired antenna configuration. It consists of two transmit and four
receive channels. The BGT60ATR24C shield facilitates fast prototyping and system integration, as well as initial
product feature evaluation. This board offers developers the flexibility to choose their own platform depending
on their preferred use cases. The sensor it incorporates various use cases, serving a broad array of applications
–including presence detection, LBC, ROA, proximity sensing, people counting/tracking, gesture recognition,
monitoring vital signs, etc. Presence detection may only require 1 mW of power in the sensor under certain
circumstances. In an automotive context, it can be of value in ROA, LBC and dashboard control. Other areas
where it might be applied are smart speakers, home/building automations and security/safety.

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XENSIV™60 GHz radar system platform
System specifications
2System specifications
2.1 Typical power consumption
The typical power consumption of the whole 60 GHz radar sensor platform, consisting of a Radar Baseboard
MCU7 and a BGT60ATR24C shield, can be found in Table 1 and Table 2. The microcontroller on the Radar
Baseboard MCU7 will change its mode of operation depending on the sensor that is plugged in and the signal
processing that is required. This will be acutely reflected in the microcontroller’s power consumption.
Table 1 Typical current consumption of the BGT60ATR24C shield
Table 2 Typical current consumption of the 60 GHz radar sensor platform
Condition
Power consumption of the BGT60ATR24C shield
Sensor attached but deactivated
(BGT60ATR24C in deep sleep mode)
~ 0.25 mW (BGT) + ~ 10 mW (crystal osc.)
BGT60ATR24C shield attached and in CW operation
(both TX on –maximum power consumption)
~ 500 mW
Condition
Power consumption of the radar system
MCU in reset
~ 10 mW
No sensor attached
~ 150 mW
Sensor attached but deactivated
(BGT60ATR24C in deep sleep mode)
~ 550 mW
BGT60ATR24C shield attached and in CW operation
(both TX on –maximum power consumption)
~ 1500 mW

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Hardware description
3Hardware description
This section of the document presents a detailed overview of the BGT60ATR24C shield’s hardware specifications.
It covers BGT60ATR24C considerations, as well as the power supply, oscillator and board interfaces.
3.1 Overview
Top view
26 mm
Bottom view
16 mm
Figure 2 Top and bottom views of the BGT60ATR24C shield
The dimensions of the BGT60ATR24C shield are 26 mm x 16 mm. The BGT60ATR24C sensor is mounted on top
of the PCB, while on the bottom patch antennas have been located. The current design of the shield uses two
Rogers laminate layers for top and bottom (RO3003 top and RO4350B bottom). More details of the PCB stackup
are mentioned in section 3.6.
To provide the correct level shifter voltage for the MCU board, the 1.8 Vsensor supply line is connected with Vdigital –
refer to “Level shifters” section of application note AN599 [1]. When the shield is plugged into the Radar
Baseboard MCU7, the sensor’s supplies are initially deactivated. Only the EEPROM is powered. The
microcontroller will read the content of the EEPROM’s memory to determine which sensor is plugged into the
sensor interface. Actually, it is not mandatory to use this EEPROM with the BGT60ATR24C, as it has an internal
chip ID which can be read by SPI directly. The EEPROM is only for ensuring compatibility with other Infineon
chips that do not have the chip ID feature.
Radar sensors are very sensitive to noise and cross-talk on the supply domains. Therefore, the different supply
domains must be decoupled. On the BGT60ATR24C shield, this is realized by a pi-shaped low-pass filter on each
supply domain (and the oscillator supply). Communication with the radar sensor is mainly performed via a
serial peripheral interface (SPI) bus. Additionally, two more digital lines are required for operation. One line
signals the microcontroller when new data needs to be fetched. The other allows the microcontroller to
perform a hardware reset of the sensor. Furthermore, an LED indicator is mounted on the board. This allows
the microcontroller to signal (for example) if the sensor is activated or deactivated at that time.
3.2 Sensor supply
Since radar sensors are very sensitive to supply voltage fluctuations or cross-talk between different supply
domains, a low-noise power supply with properly decoupled supply rails will prove vital. The Radar Baseboard
MCU7 provides a low-noise supply (see section 2.2 of application note AN599 for further details). Figure 3
depicts the schematics of the pi-shaped low-pass filters employed to decouple the supplies of the different

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Hardware description
power rails in the chip. High attenuation of voltage fluctuations in the MHz range is provided by ferrite beads.
For example, the SPI (which runs at up to 50 MHz) induces voltage fluctuations in the digital domain. These
fluctuations would then transfer into the analog domain if not for the decoupling filters incorporated. The
ferrite beads are chosen because they can handle the maximum current of the sensor (approximately 200 mA)
with a low DC resistance (below 0.25 Ω) and an elevated inductance. The high inductance figure will reduce the
cut-off frequency of the low-pass filter, thereby providing better decoupling at lower frequencies.
Figure 3 Schematics of the low-pass filters
3.3 Oscillator
Infineon’s XENSIV™BGT60ATR24C radar sensor requires an external 80 MHz oscillator with low phase jitter and
low phase noise to provide a stable system reference clock. Therefore, the BGT60ATR24C shield employs an
NDK NZ2520SHA quartz oscillator, as depicted in Figure 4. This oscillator source will output a stable 1.8 V digital
signal. The most important parameters when choosing an oscillator are phase jitter and phase noise. Other
oscillators should have similar phase jitter and phase noise to the NDK NZ2520SHA. The R6 series resistor
reduces the RF level at the sensor so that it is at the optimal range for the BGT60ATR24C. If a redesign of the
board contains a different signal source or a vastly different layout is implemented, the value of R1 (150 Ω) may
have to be adjusted. A higher resistance results in a lower signal at the radar sensor. If the signal level is too
low, the phase noise of the sensor will degrade. With a low resistance, the signal level at the sensor will be
heightened. Consequently, in the range-Doppler illustration of the radar data, a peak (or ghost target) will
appear for low distances.
Figure 4 The oscillator circuit on the BGT60ATR24C shield
For this reason, the phase noise needs to be measured as well as the radar data. This can be illustrated with a
range-Doppler plot to optimize the series resistance of the layout. The series resistance must be varied by
soldering different resistors into the circuit. An optimized series resistance will show ideal phase noise behavior
of the sensor, paired with a clean range-Doppler plot. If the phase noise behavior is non-ideal, the resistance
value must be lower. If a peak appears in the range-Doppler plot, the resistance must be higher.

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Hardware description
3.4 Connectors
The BGT60ATR24C shield is an extension board of Infineon’s XENSIV™60 GHz radar system platform (without a
microcontroller included). The shield must be connected to a microcontroller board, like the Radar Baseboard
MCU7.
The main connector interface of the BGT60ATR24C shield contains two Hirose DF40C-20DP-0.4V connectors. On
the microcontroller side, the Radar Baseboard MCU7 contains the corresponding DF40HC(3.5)-20DS-0.4V(51)
connectors on its bottom side. Figure 5 describes the pin-out and the pad layout of the Hirose connectors on
the BGT60ATR24C shield. To provide the information of the correct digital signal level to the host board, the
line Vdigital is shorted with the 1.8 V supply. The RF shield and the MCU7 board have to be properly aligned, as
depicted in Figure 1.
There is a risk of the Hirose connectors wearing out when regularly plugged into and unplugged from the
shield. To prevent this, it is recommended not to lift the board out of the connector on the short side. Instead,
simply pull on the long side of the board, thereby tilting the short side. This will significantly increase the
operational lifetime of the connectors.
Figure 5 Pin-out of the sensor connectors on the BGT60ATR24C shield
3.5 EEPROM
The BGT60ATR24C shield contains an EEPROM memory to store data such as the board identifier. Its
connections can be seen in Figure 6.
Figure 6 Schematics of the EEPROM

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Hardware description
3.6 Layer stackup
Since the antennas are integrated on the PCB, the stackup must be chosen carefully. For low loss and enhanced
performance, the stackup shown in Figure 7 is selected. All the vias in Figure 7 are mechanically drilled except
for the blind vias between L1_Top and L2_GND, which are laser drilled.
Note: IS400 is similar to FR4 material
Figure 7 Layer stackup and via types
3.7 Metal layers overview
Figure 8 through to Figure 12 show the different metal layers of the PCB. Layer 1 comprises SMD components,
the BGT60ATR24C chipset and matching networks. Layer 2 consists of the ground plane for RF structures
situated on Layer 1. Layer 3 consists of signal lines and power planes with the voltage domains required for
BGT60ATR24C and other components. Layer 4 is the ground plane for the antennas that are placed on layer 5.
Figure 8 Layer 1 –RF layer, component side

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XENSIV™60 GHz radar system platform
Hardware description
Figure 9 Layer 2 –GND plane for component side
Figure 10 Layer 3 –signal/power layer
Figure 11 Layer 4 –GND plane for antenna side
Figure 12 Layer 5 –RF layer, antenna side

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XENSIV™60 GHz radar system platform
Layout overview
4Layout overview
4.1 Component side
Layer 1 is the component side. It comprises important elements for the RF performance of the shield.
•BGT60ATR24C radar chip
•TX matching structures
•RX matching structures
•Lines to the feed-throughs to the antenna side
The matching structures transform BGT60ATR24C’s chip impedances at the package side into 50 . The
transmission lines to the feed-throughs correct for phase differences between the channels (see section 5.1) so
that all RX channels and TX channels are in phase at the antenna side.
In order to work correctly, all these RF structures on the component side need a certain distance between the
board and the other objects. Simulation has shown that this distance should be more than 1.8 mm. This is the
reason why the shield should be plugged into the MCU7 board at the side with the higher connectors.
The copper areas between the matching structures and transmission lines, as well as the vias next to them, will
help to increase the isolation between the single RX and TX channels.
The solder mask was removed in all RF relevant areas of the board, as otherwise it would degrade the RF
performance.
BGT60ATR24C TX matching structuresRX matchingstructures
TX feed-through
RX feed-through
Figure 13 Top layer overview, component side
4.2 Antenna side
The antenna side consists of the six different antennas. The structures between the TX and RX side will increase
the TX to RX isolation. The structures around the single sides prevent radiation in unwanted directions.
There is no solder mask on the antenna side, again in order to improve RF performance.
The single TX and RX antennas are placed in such a way that the board, if MIMO techniques are being used, has
multiple virtual antennas - three for horizontal scanning, and four for vertical scanning. Figure 16 explains the
principle behind this.

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XENSIV™60 GHz radar system platform
Layout overview
TX antennas RX antennas
Figure 14 Bottom layer overview, antenna side
RX1RX3
RX2
RX4
TX1
TX2
RX1RX3
RX2
RX4
TX1
TX2
Figure 15 Antenna naming
TX antennas RXantennas
Physical antennas 3x4 virtual antenna array
Figure 16 MIMO antenna array

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XENSIV™60 GHz radar system platform
TX and Rx channels
5TX and Rx channels
5.1 Phase relationship between RF channels
Due to BGT60ATR24C device’s topology, the phase between single channels is partly shifted by 180°
5.1.1 TX outputs
The TX outputs have a phase difference of 180°, as shown in Figure 17.
Buffer
TX1
TX2
0°
180°
0°
180°
Figure 17 Phase relationship of TX outputs
5.1.2 RX channels
Due to the local oscillator (LO) distribution on the chip, single RX channels show a relative phase shift of 180° at
the intermediate frequency (IF) side (Figure 18). In order to get phase correct results in signal processing, this
phase shift needs to be compensated. This can be done either via hardware (by adding 180° phase on the RX
side for the respective channels) or in software.
RX4
RX2
0°
180°
RX1
RX3
180°
Buffer
Buffer
LO
0°
180°
IF
Buffer
+180°
360° = 0°
+0°
+0°
+180°
Figure 18 IF phase shift relative to LO signal
Table 3 Phase shift at IF outputs relative to LO
RX channel
Phase shift
RX1, RX2
180°
RX3, RX4
0°

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Measurement results
6Measurement results
6.1 Transmitter and receiver antenna matching
The antennas of this shield have been designed on a 0.4 mm Rogers RO4350B laminate substrate. This is a
thicker substrate, when compared to the 0.127 mm thick substrate used for the top layer, it allows higher
antenna bandwidths to be supported. All measurements include the feed-throughs from the top layer.
The achieved bandwidth here is over 4 GHz. The antennas’ center frequency is shifted to higher frequencies but
can be moved to the center of the BGT60ATR24C MMIC’s frequency band by fine tuning.
Figure 19 Measured RX antenna matching, including feed-throughs
Figure 20 Measured TX antenna matching, including feed throughs

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Measurement results
6.2 System radiation characteristics
The following graphs show the radiation characteristics of the complete board. The single TX channels have
been used as signal sources. A corner reflector with 1 m² of radar cross section (RCS) has been used as a target.
The single RX channels have been used as receivers. The RF shield was turned in 2° steps over the vertical and
horizontal cut planes. Figure 21 shows the definition of these planes. Frequency-modulated continuous wave
(FMCW) chirps of 500 MHz bandwidth were used as test signals. Start frequencies were changed in 500 MHz
steps from 58 GHz to 62 GHz.
The received amplitudes were normalized to the peak value of the respective cut plane considering data from
every RX channel.
The plots show that the system works well over the BGT60ATR24C MMIC’s entire frequency range. The antennas
will still need some fine tuning, especially RX2.
Horizontal plane
Vertical plane
Figure 21 Horizontal and vertical cut planes

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Measurement results
Figure 22 Amplitudes received by RX1 over angle, polarizations, transmitters, and frequency

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Measurement results
Figure 23 Amplitudes received by RX2 over angle, polarizations, transmitters, and frequency

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Measurement results
Figure 24 Amplitudes received by RX3 over angle, polarizations, transmitters, and frequency

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Measurement results
Figure 25 Amplitudes received by RX4 over angle, polarizations, transmitters, and frequency

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References
References
[1] Infineon Technologies AG. AN599: Radar Baseboard MCU7
[2] Committee, E. C. (n.d.). ERC Recommendation. Retrieved 03 12, 2019, from
https://www.ecodocdb.dk/download/25c41779-cd6e/Rec7003.pdf
[3] European Telecommunications Standards Institute. (n.d.). Retrieved 03 12, 2019, from
https://www.etsi.org/
[4] Federal Communications Commission. (n.d.). Retrieved 03 12, 2019, from https://www.fcc.gov/
[5] Institute, E. T. (n.d.). EN 305 500. Retrieved 03 12, 2019, from
https://www.etsi.org/deliver/etsi_en/305500_305599/305550/02.01.00_20/en_305550v020100a.pdf
[6] Regulations, E. C. (n.d.). §15.255. Retrieved 03 12, 2019, from https://www.ecfr.gov/cgi-bin/text-
idx?SID=a484297320706bbafb187c022e7b3c0c&mc=true&node=se47.1.15_1255&rgn=div8

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XENSIV™60 GHz radar system platform
Revision history
Revision history
Document
revision
Date
Description of changes
1.00
2022-11-08
Initial version
1.10
2023-02-14
Miscellaneous document cleanup updates