Infineon BGT60LTR11AIP EBG User manual

Application note
Please read the sections “Important notice” and “Warnings” at the end of this document
Revision 1.00
www.infineon.com
2023-02-14
AN661
BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
B o a r d v e r s i o n V 3 .1
About this document
Scope and purpose
This application note describes the function, circuitry, and performance of the 60 GHz radar BGT60LTR11AIP
EBG shield, part of Infineon’s XENSIV™ 60 GHz radar system platform. The shield provides the supporting
circuitry to the on-board BGT60LTR11AIP monolithic microwave integrated circuit (MMIC) Infineon’s 60 GHz
radar chipset with antenna-in-package (AIP). An electromagnetic band gap (EBG) structure is added to reduce
the impact of the neighboring components on the radar MMIC resulting in a homogeneous field of view (FoV),
which makes the BGT60LTR11AIP the appropriate choice for ceiling-mounted applications. In addition to the
autonomous mode configuration, the shield offers a digital interface for configuration and transfer of the
acquired radar data to a microcontroller board, e.g., Radar Baseboard MCU7.
Intended audience
The intended audiences for this document are design engineers, technicians, and developers of electronic
systems, working with Infineon’s XENSIV™ 60 GHz radar sensors.
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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BGT60LTR11AIP EBG 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.............................................................................................................................................4
2System specifications............................................................................................................. 5
3Hardware description............................................................................................................. 6
3.1 Overview..................................................................................................................................................6
3.2 BGT60LTR11AIP MMIC.............................................................................................................................7
3.3 Sensor power supply...............................................................................................................................9
3.4 Crystal......................................................................................................................................................9
3.5 External capacitors................................................................................................................................10
3.6 Connectors ............................................................................................................................................12
3.7 EEPROM .................................................................................................................................................12
3.8 LEDs and level shifters ..........................................................................................................................13
3.9 MMIC quad-state inputs........................................................................................................................14
3.10 Electromagnetic bandgap structure ....................................................................................................14
3.11 Layer stackup and routing ....................................................................................................................16
4Radar MMIC settings configuration..........................................................................................17
4.1 Operation mode ....................................................................................................................................17
4.2 Detector threshold ................................................................................................................................19
4.3 Detector hold time ................................................................................................................................20
4.4Operating frequency .............................................................................................................................21
4.5 Pulse repetition time.............................................................................................................................22
5Autonomous mode operation .................................................................................................23
5.1 Battery-powered operation..................................................................................................................23
5.2 Arduino MKR operation.........................................................................................................................23
6Firmware .............................................................................................................................24
6.1 Overview................................................................................................................................................24
6.2 SPI MISO arbitration..............................................................................................................................24
7Measurement results.............................................................................................................28
7.1 Radiation pattern simulation results....................................................................................................28
7.2 Motion detection area...........................................................................................................................29
7.2.1 Autonomous mode ..........................................................................................................................29
7.2.2 SPI mode and MMIC internal detector.............................................................................................30
7.2.3 SPI mode and motion detection algorithm ....................................................................................31
7.2.4 On-ceiling measurements................................................................................................................32
8Power consumption analysis ..................................................................................................34
8.1 Duty cycling ...........................................................................................................................................34
8.2 Adaptive pulse repetition time .............................................................................................................35
References....................................................................................................................................37
Revision history.............................................................................................................................38
Disclaimer.....................................................................................................................................39

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Introduction
1Introduction
1.1 60 GHz radar system platform
The BGT60LTR11AIP MMIC is a fully integrated microwave motion sensor including AIP elements, built-in
motion and direction of motion detectors, and a state machine allowing fully autonomous operation of the
MMIC without any external microcontroller. An integrated frequency divider with a phase-locked loop (PLL)
provides voltage-controlled oscillator (VCO) frequency stabilization. These features make the small-sized radar
solution a compelling, smart and cost-effective replacement for conventional passive infrared (PIR) sensors in
low-power or battery-powered applications. The MMIC is designed to operate as a Doppler motion sensor in the
60 GHz ISM band.
The MMIC has four quad-state (QS1 to 4) input pins that give the performance parameters flexibility even when
it is running in autonomous mode. These pins are used for configuration of the MMIC, as explained in section
3.8.
The MMIC supports multiple operation modes, including autonomous mode and serial peripheral interface
(SPI) mode, which can be selected via the QS1 pin (see Table 4).
In autonomous mode, the detection threshold (or sensitivity) is set via the QS2 pin (see Table 5) and has 16
different levels to fulfill a configurable detection range from 0.5 m up to 7 m with a typical human target radar
cross-section (RCS). The hold time is also configurable in 16 levels via the QS3 pin (see Table 6), which allows
detection status holding up to 30 minutes. The device operating frequency can be configured via the QS4 pin
(see Table 8) and has four different possible frequencies between 61.1 and 61.4 GHz for BGT60LTR11AIP MMIC.
In this mode, the integrated detectors deliver digital output signals indicating motion and direction of motion
(approaching or departing) of a target.
In SPI mode, full flexibility regarding radar MMIC parameter configuration –e.g., detection threshold, hold time
and operating frequency –is offered by writing into the MMIC registers the desired configuration, using an
external microcontroller unit (MCU). In this mode the integrated detectors, if not disabled, will also deliver
digital outputs indicating motion and direction of motion. If further signal processing is needed, the radar raw
data can be extracted and sampled from the BGT60LTR11AIP MMIC and then used to develop customized
algorithms for maximum performance.
The BGT60LTR11AIP EBG shield demonstrates the features of the BGT60LTR11AIP MMIC and gives the user a
“plug and play” radar solution. The shield can also be attached to an Arduino MKR board or an Infineon Radar
Baseboard MCU7. A graphical user interface (GUI) is available via Infineon Developer Center (IDC) in order to
display and analyze acquired data in the time and frequency domains.
20.20 mm
19.15 mm
BGT60LTR11AIP MMIC BGT60LTR11AIP EBG shield BGT60LTR11AIP Demo
= Radar Baseboard MCU7
+ BGT60LTR11AIP EBG shield
Figure 1 BGT60LTR11AIP EBG shield using BGT60LTR11AIP MMIC

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Introduction
1.2 Key features
The BGT60LTR11AIP EBG shield is optimized for fast prototyping designs and system integrations, as well as
initial product feature evaluations. In addition, the sensor can be integrated into systems like laptops, tablets,
TVs, speakers, etc. to “wake”them up based on motion (or direction of motion) detection, put them to sleep or
auto-lock when no motion is detected for a defined amount of time. This way, it can be a smart power-saving
feature for these devices and might also eliminate the need for keyword-based activation of systems. Radar
sensors offer the possibility of being hidden inside the end product because they operate through non-metallic
materials. This enables a seamless integration of technology into our day-to-day lives.
Some key features of the BGT60LTR11AIP EBG shield are as follows:
•Form factor of 20.20 mm x 19.15 mm for the BGT60LTR11AIP EBG shield
•Features an AIP MMIC of small size (6.7 mm x 3.3 mm x 0.56 mm), thereby eliminating antenna design
complexity at the user end
•Features an EBG structure, which can improve the isolation between the sensor package and PCB circuitry,
thereby reducing the impact of the PCB layout and size on the radiation pattern and allowing a symmetrical
FoV for on-ceiling application
•Detects motion and direction of movement (approaching or departing) for a human target
•Works standalone (autonomous mode) or with SPI mode to interface with an external microcontroller
•Configurable settings such as operation mode, detector threshold, detector hold time, operating frequency
•Low power consumption
•Option to solder onto other PCBs such as Arduino MKR for extra flexibility

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
System specifications
2System specifications
Table 1 gives the specification of the BGT60LTR11AIP EBG shield.
Table 1 BGT60LTR11AIP EBG shield specifications
Parameter
Unit
Min.
Typ.
Max.
Comments
System performance
Detection range
m
–
5
7
Typical motion detection range for
human target at low threshold (in
both E-plane and H-plane
orientations)
Power supply
Supply voltage
V
1.5
3.3
5.0
Current consumption
mA
3.48
At 3.3 V supplied via castellated holes
Pulse Repetition Time (PRT) = 500 µs
Pulse Width (PW) = 5 µs
(LEDs off)
Antenna characteristics (measured)
Antenna type
1 x 1
AIP
Horizontal –3 dB beamwidth
(HPBW)
Degrees
80
At frequency = 61.25 GHz
Elevation –3 dB beamwidth
(HPBW)
Degrees
80
At frequency = 61.25 GHz

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
3Hardware description
This section presents a detailed overview of the BGT60LTR11AIP EBG shield’s hardware (HW) building blocks,
such as BGT60LTR11AIP MMIC, power supply, crystal and board interfaces.
3.1 Overview
The BGT60LTR11AIP EBG shield is a very small PCB of 20.2 mm x 19.15 mm size. Mounted on top of the PCB is a
BGT60LTR11AIP, Infineon’s 60 GHz radar sensor. The PCB can be manufactured using a standard FR4 laminate,
as the antennas are integrated into the chip package. The bottom side of the shield has the connectors to the
Radar Baseboard MCU7 [1] (P1 and P2 in Figure 2) and the rest of the components such as LDO, quartz oscillator
and level shifter. On the top side of the shield, there is a marker that must be aligned with the marker on the
Radar Baseboard MCU7 for correct alignment, as shown in Figure 3.
The castellated holes on the edges of the PCB provide additional access to the detector outputs and power
supply signals of the shield.
20.2 mm
19.15 mm
Top view Bottom view
Sensor connectors (P1 and P2)
Castellated holes
Figure 2 Top and bottom views of the BGT60LTR11AIP EBG shield
Marker has to be
on the top left
when the shield
is plugged into
the Radar
Baseboard MCU7
60 GHz radar system platform
Figure 3 Markers on Radar Baseboard MCU7 and BGT60LTR11AIP EBG shield for alignment

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
Note: There is a risk of the connectors wearing out when regularly plugged into and unplugged from the
shield. To prevent this, do not lift the shield on the short side out of the connector. Instead, simply
pull on the long side of the sensor, thereby tilting the short side. This will significantly increase the
lifetime of the connectors.
38.4 MHz
quartz
EEPROM
LED1
LED2
2
1.8 V or 3.3 V LDO
1.5V_RF
1.5V_PLL
SPI
IRQ
TDet
PDet
IFI
IFQ
Castellated Holes
5
3.3 V
Vin
Vin 1.5V_RF
1.5V_RF
Vin
2
Connectors to Radar Baseboard MCU7
BGT60LTR11AIP MMIC
Figure 4 BGT60LTR11AIP EBG shield block diagram
The block diagram in Figure 4 depicts the configuration of the shield. When the shield is plugged into the Radar
Baseboard MCU7, the MMIC’s supplies are initially deactivated. Only the EEPROM is powered. The MCU reads
the content of the EEPROM’s memory to determine which shield is plugged into the connectors. The MMIC’s
supplies are activated only when the shield has been correctly identified.
Communication with the MMIC is mainly performed via a SPI. The BGT_RTSN allows the MCU to perform a HW
reset of the MMIC. The BGT_SELECT and BGT_RTSN lines of the SPI should be pulled up with 10 kΩ resistors.
The interrupt request (IRQ) line can be used to trigger the MCU when new data need to be fetched.
3.2 BGT60LTR11AIP MMIC
The BGT60LTR11AIP MMIC (Figure 5) serves as the main element on the BGT60LTR11AIP EBG shield. The MMIC
has one transmit antenna and one receive antenna integrated into the package. The package dimensions are
6.7 mm (±0.1 mm) x 3.3 mm (±0.1 mm) x 0.56 mm (±0.05 mm), as illustrated in Figure 6 and Figure 7.
The MMIC has an integrated VCO and PLL for high-frequency signal generation. The transmit section consists of
a medium-power amplifier (MPA) with configurable output power, which can be controlled via the SPI.
The chip features a low-noise quadrature receiver stage. The receiver uses a low-noise amplifier (LNA) in front
of a quadrature homodyne down-conversion mixer in order to provide excellent receiver sensitivity. Derived
from the internal VCO signal, an RC poly-phase filter (PPF) generates quadrature LO signals for the quadrature
mixer.

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
The analog baseband (ABB) unit consists of an integrated sample-and-hold (S&H) circuit for low-power duty-
cycled operation followed by an externally configurable HPF, a variable-gain amplifier (VGA) stage and a low-
pass filter (LPF).
The integrated target detector circuits in the MMIC indicate the detection of movement in front of the radar and
the direction of movement with two digital signals (BGT_TARGET_DET and BGT_PHASE_DET). See section 3.9
for more details. The detector circuit offers a user-configurable hold time for maximum flexibility.
Figure 5 BGT60LTR11AIP MMIC block diagram
Figure 6 Package and pin-signal assignment of the BGT60LTR11AIP MMIC
VDD_RF
A2
QS3
B1 PDET D1
QS4
M1
SPIDO
B6
VTUNE
C1
IFQ K1
TDET E1
PLL_TRIG
G1
VDD_PLL
M2
QS1
M6
VDD_RF
B2
SPIDI
B5
GND M4
GND N4
GND N6
GND N1
GND B3
GND A3
IFQAI
M5
GND B4
GND N3
XOSC_AI
J1
SPIRST_N
A5
GND A6
DIV_O F1
GND A1
IFI L1
XOSC_AO
H1
VDD_PLL
N2
GND A4
QS2
N5
GND M3
SPICLK
C6
SPICS
D6
IFIAO E6
IFIAOX F6
IFIAIX
G6 IFIAI
H6
IFQAO J6
IFQAOX K6
IFQAIX
L6
U1
BGT60LTR11AiP
Xosc_ao
Xosc_ai
QS1
QS2
QS3
QS4
BGT_SCK_1.5_A
BGT_SELECT_1.5_A
BGT_MISO_1.5_A
BGT_MOSI_1.5_A
BGT_RTSN_1.5_A
BGT_PLL_TRIG_1.5
BGT_VTUNE
VTUNE
BGT_TARGET_DET
BGT_DIV
BGT_PHASE_DET
GND
VDD_RF
VDD_PLL
IF1i_P
IF1i_N
IF1q_P
IFI
IFQ
IFQx_PostLPF
IFQ_PostLPF
IFIx_PostLPF
IFI_PostLPF
IF1q_N

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
Top view Side view Bottom view
Figure 7 Top, side and bottom views of the BGT60LTR11AIP MMIC package –all dimensions in mm
3.3 Sensor power supply
Because radar sensors are very sensitive to supply voltage fluctuations or crosstalk between different supply
domains, a low-noise power supply is vital, as well as properly decoupled supply rails. The Radar Baseboard
MCU7 provides a low-noise power supply. Figure 8 depicts the schematics of the LPFs employed to decouple
the supplies of the different power rails in the BGT60LTR11AIP EBG shield. High attenuation of voltage
fluctuations in the MHz regime is provided by ferrite beads (L1, L3 and L5). For example, the SPI, which runs up
to 50 MHz, induces voltage fluctuations on the digital domain, which would then couple into and interfere with
the analog domain without the decoupling filters. The ferrite beads are chosen such that they can handle the
maximum current of the sensor with a low DC resistance (below 0.25 Ω) and an inductance as high as possible.
The high inductance will reduce the cut-off frequency of the LPF, which provides better decoupling for lower
frequencies.
Figure 8 Schematics of the sensor supply and LPFs
3.4 Crystal
The MMIC requires an oscillator source with a stable reference clock providing low phase jitter and low phase
noise. The oscillator is integrated inside the MMIC. This reduces current consumption, as crystal oscillators
1V5Sensor1V8Sensor L1
MMZ0603S121HT000
Vin VDD_RF
3V3Sensor
1V5_LDO
L3
DNP
GND 2
OUT 1 IN
4
EN
3
EPAD
5
U2
NCP163AMX150TBG
C1
4.7µF C2 100nF
GND
R24
0
C3
4.7µF C4 100nF
GND GND
3V3 L5
MMZ0603S121HT000 GND VDD_PLL
C7
100nF
GND
GND
R23
0
R22
DNP

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
consume only a few milliamperes (mA) and run continuously. The BGT60LTR11AIP EBG shield uses a 38.4 MHz
crystal oscillator, as shown in Figure 9.
Figure 9 The crystal circuit on the BGT60LTR11AIP EBG shield
3.5 External capacitors
The BGT60LTR11AIP MMIC is duty-cycled and performs a S&H operation for lower power consumption. The S&H
switches are integrated into the chip at each differential IQ mixer output port. They are controlled
synchronously via the internal state machine. The capacitors between S&H and the HPF are external (Figure
10). C10, C11, C14 and C15 are 5.6 nF capacitors used as “hold” capacitors for the S&H circuitry. They can be
configured for different PW settings, as shown in Table 2. C8, C9, C12 and C13 are the DC blocking (or high-pass)
capacitors. They should have a value of 10 nF to get a high pass of 4 Hz (if internal high-pass resistor RHP =
4 MΩ). It is not recommended to use higher values as this will affect the ABB settling time. The DC blocking
capacitors are important because the mixer output has a different DC voltage than the internal ABB. In Figure
10 the external hold 󰇛󰇜and high-pass capacitors 󰇛󰇜are shown for all four branches in the differential
IQ configuration.
Figure 10 External capacitors
Table 2 Recommended hold capacitors (C10, C11, C14 and C15) for different PW values
Charging time of the hold capacitor 󰇛󰇜is limited to the selected PW. Shorter PWs require smaller  to
become ~90% percent charged during one pulse. Rise-time is controlled by the  itself and the internal
mixer output resistance 󰇛󰇜of 300 Ω in each branch.
1 3
2 4
Y1 FH3840024Z
GND
GND
GND
C16
11pF
C17
16pF
GND
Xosc_ai Xosc_ao
IF1i_PIF1q_P IFI_PostLPFIFQ_PostLPF
C8 10nF C9 10nF
GND GND
C10
5.6nF C11 5.6nF
IF1q_N IF1i_N IFIx_PostLPFIFQx_PostLPF
C12 10nF C13 10nF
GND GND
C14
5.6nF C15
5.6nF
PW (µs)
Hold capacitor value (nF)
3
4.7
4
5.6
5 (default)
5.6 (default)
10
15

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
BGT60LTR11AIP IFIAix
CHP
Chold
IFIAox
S&H switch
Rmixer_out
Pulsed mixer output
(AC + DC
superposed)
RHP
VCC /2
External capacitors
Figure 11 External capacitors for BGT60LTR11AIP
Longer PW can have a higher  value. This leads to a reduced BW of the RC filter (& ).
Consequently, there will be a lower baseband noise because of reduced noise folding BW.
For this RC structure, the low-pass 3 dB cut-off frequency 󰇛
󰇜can be calculated under the following
conditions:
 = 10% / 90% = S&H on-time = 4 µs
PW = 5 µs
 = 

 



Or based on the formula:

 
    
  
 󰇛󰇜
The high-pass 3 dB cut-off frequency 󰇛
 󰇜can be calculated under the following conditions:
 = 10 nF
 =4 M

 
    
  
      

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
3.6 Connectors
The BGT60LTR11AIP EBG shield can be connected to an MCU board like the Radar Baseboard MCU7, with the P1
and P2 connectors. Visible on the top and bottom side of the PCB are the castellated holes (P3 and P4). TD and
PD pins of the castellated holes correspond to the internal detector outputs of the MMIC.
The shield contains two Hirose DF40C-20DP-0.4 V connectors, P1 and P2. The corresponding DF40C-20DS-0.4 V
connectors are on the Radar Baseboard MCU7. Figure 12 illustrates the pinout of the Hirose connectors of the
BGT60LTR11AIP EBG shield.
The signal IRQ is connected with a R5 resistor (0 Ω) to the divider output (BGT_DIV) of the MMIC. In SPI pulsed
mode, BGT_DIV generates a signal that acts as an interrupt signal for the MCU to start ADC acquisition. BGT_DIV
could also be used to measure divider frequency.
Bottom view
Sensor connectors (P1 and P2)
Castellated holes
Figure 12 Connectors on the BGT60LTR11AIP EBG shield, and their pinouts
3.7 EEPROM
The BGT60LTR11AIP EBG shield contains an EEPROM (24CW1280T-I/CS0668) connected via an I2C interface to
store data like a board identifier. Its connections can be seen in Figure 13. This EEPROM contains a descriptor
indicating the type of shield board and MMIC. This is used by the firmware (FW) to communicate properly with
the shield.

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
Figure 13 Schematics of the EEPROM
3.8 LEDs and level shifters
The shield has two LEDs to indicate the motion detection (green) and the target’s direction of motion (red), as
shown in Figure 14, where R1 and R2 are limiting resistors. The digital block within the detector in the MMIC
evaluates and sets the target detect/phase detect outputs of the BGT60LTR11AIP MMIC. Target detect (TDet)
output is active low. Phase detect (PDet) output is used to show the direction of the detected target. It is set to
high for approaching targets, otherwise it is low. The default state for PDet is low.
The outputs from the MMIC are at the voltage level of 1.5 V. They are level-shifted to the voltage level of Vin by
using the circuit shown in Figure 14. In the circuit, BGT_TARGET_DET and BGT_PHASE_DET are outputs of MMIC
(1.5 V voltage level). VDD_RF is 1.5 V and Vin is 3.3 V (when connected with Radar Baseboard MCU7).
•When BGT_TARGET_DET is high (1.5 V), NMOS is off (Vgs = 0 V), and Target_Det_Out is 3.3 V through the R14
pull-up resistor.
•When BGT_TARGET_DET is low (0 V), NMOS is on (Vgs = 1.5 V), and Target_Det_Out is pulled down to 0 V.
The same applies to the BGT_PHASE_DET signal.
Table 3 LED detection
Figure 14 Connections of the LEDs and level shifter
VCC
A1
SCL
B1
VSS A2
SDA B2
U3
24CW1280T-I/CS0668
GND
3V3digital1
I2C_SDAI2C_SCL
3V3digital1
R11
2k2 R12 2k2
VDD_RF
Vin
1
2
6
Q1A
BSD840N
R13
100k R14 10k Target_Det_OutBGT_TARGET_DET
VDD_RF
Vin
5
34
Q1B
BSD840N
R15
100k R16 10k Phase_Det_OutBGT_PHASE_DET
VinVin
R1
1k R2 1k
12
T
Green LED
12
P
Red LED
Phase_Det_OutTarget_Det_Out
LED
Mode
Comments
Green
On –target detected
Off –target not detected
Target_Det_Out is an active low signal
Red
On –target departing
Off –target approaching
Phase_Det_Out is an active low signal

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
3.9 MMIC quad-state inputs
The BGT60LTR11AIP MMIC has four quad-state inputs QS1 to 4, used in autonomous mode to set the device
configuration. Figure 15 shows the default settings of these QS pins on the BGT60LTR11AIP EBG shield.
To offer more flexibility in autonomous mode, an “Advance mode” is enabled when the BGT_PLL_TRIG pin is
kept as “1” during chip boot and QS1 is either GND or OPEN, where BGT_MOSI and BGT_SCK pins are also
sampled to determine the PRT. In addition, pins QS2 and QS3 are evaluated by the ADC and converted into
4-bit values before each “mean window”.
QS1
QS2
QS3
BGT_PLL_TRIG
QS4
BGT_SCK
BGT_MOSI
Figure 15 MMIC QS1 to QS4 quad-state inputs (PCB bottom side)
For more details on the BGT60LTR11AIP MMIC quad-state inputs, please refer to AN625: User’s guide to
BGT60LTR11AIP [2].
3.10 Electromagnetic bandgap structure
Infineon’s BGT60LTR11AIP achieves an excellent antenna performance for small size and low cost. If there is
additional space on the PCB, the performance can even be improved through the use of EBG structures. Indeed,
it can happen that part of the RF signal couples onto the PCB through the solder balls and via radiation or
coupling. Those electromagnetic signals will then be reflected at metallic surfaces on the PCB or can travel as
surface waves on the PCB, resulting in radiation from various PCB structures and the PCB edges. The reflected
or re-radiated RF signal portions from the PCB will superimpose with the initial RF signal radiated by the sensor
antennas. Depending on the phases, this can lead to constructive or destructive interference and will cause
deviations of the resulting radiation pattern from the radiation pattern of the sensor antennas. As a result, the
PCB design and size can have a noticeable impact on the resulting radiation pattern of the system.
A solution to overcome this challenge and reduce the sensitivity of the resulting radiation pattern from the PCB
design is the use of an EBG structure placed on the PCB around the sensor package.
The EBG structure has two important effects. Reflections of an electromagnetic wave travelling perpendicular
to the surface of the EBG structure will behave in a similar way to reflections from a regular metal plane, but
without the 180-degree phase shift. Furthermore, the EBG structure strongly reduces the propagation of

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
surface waves on the PCB, leading to less radiation from PCB structures and PCB edges. Both effects result in
fewer deviations of the initial radiation pattern by the PCB.
The EBG in general consists of multiple identical elements placed in a uniform grid. The literature provides
various EBG element designs utilizing different geometries. The geometry of the EBG element defines the
inductance and capacitance between neighboring elements and, if present, further PCB layers, which will result
in a specific operating frequency band of the individual EBG design.
The EBG element design used for the BGT60LTR11AIP RF shield can be seen in Figure 16. The EBG consists of a
rectangular patch with a centered via connection to the internal PCB GND layer.
Top view Cross-section
w: 550 µm
g: 300 µm
d: 200 µm
I: 360 µm
Figure 16 EBG geometry designed for 61 GHz radar on FR4
The size of the patch 󰇛  󰇜and the periodicity 󰇛    󰇜are designed for an operation
frequency around 61 GHz on a FR4 substrate with a thickness of the first laminate layer of 󰇛  󰇜and a
via diameter 󰇛  󰇜. It is important to highlight that this specific EBG design is only valid for the chosen
substrate thickness, substrate material and via diameter. Any changes to these values might require a redesign
of the EBG structure to adjust the operating frequency.
The first inner metal layer forms a continuous GND plane underneath the EBG structure. Therefore, only the
thickness of the first laminate layer is relevant for this EBG design, and the thickness of the other layers can be
customized. Blind vias can be used to simplify the routing underneath the EBG area.
At least three rows of EBG elements in every direction around the sensor are recommended for a significant
effect. Additional rows of EBG elements will further decrease the sensitivity of the radiation pattern toward the
remaining PCB layout. This results in a trade-off between the area occupied by the EBG elements and radiation
performance.
The EBG structure does not necessarily have to be part of every design. For many applications, reasonable
performance has been demonstrated without the EBG structure. It is also worth mentioning that the use of the
EBG concept will not inherently improve every existing design. But when the PCB design has a strong impact on
the radiation pattern, the EBG can improve the situation.
Nevertheless, applying the EBG structure around the sensor with sufficient elements can be a solution to
provide consistent radiation performance on custom PCB layouts without the need for EM simulations or
multiple optimization steps.

Application note
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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Hardware description
3.11 Layer stackup and routing
The PCB is designed with a four-layer stackup with standard FR4 material. Figure 16 shows the different layers
and their thicknesses.
Figure 17 PCB layer stackup in 2D and 3D views
In the routing on the PCB, the VTUNE pin on the BGT60LTR11AIP MMIC should be left floating. Any components
added to the line, or a long wire being connected, can result in spurs.

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Radar MMIC settings configuration
4Radar MMIC settings configuration
The radar MMIC can be configured in two different operation modes. In autonomous mode, the sensor
configuration parameters are set via QS pins and external resistors. In SPI mode, the connection to a
microcontroller allows setting the sensor configuration parameters by writing in the internal registers through
SPI.
R3
R10R9R6
R18 R19 R20
Threshold
Hold time
Figure 18 QS1 to QS4 schematic and layout connections
4.1 Operation mode
The QS1 pin allows choosing the operation mode of the radar MMIC, as detailed in Table 4.
Table 4 QS1 settings
The BGT60LTR11AIP EBG shield is configured by default in SPI mode, to enable radar MMIC configuration via
the FW running on the Radar Baseboard MCU7 microcontroller.
VDD_RF
GND
VDD_RF
R9
DNP R19
DNP
QS2 QS3
VDD_RFVDD_RF
R3
0R R4
DNP
QS1 QS4
GND GNDGND
VDD_RF
GND
R6
0R
BGT_MOSI_1.5_A BGT_SCK_1.5_A
R27
100K R29
100K
GND GND
VDD_RF VDD_RF
J3
DNP J4
DNP
J1
DNP J2
0R
BGT_PLL_TRIG_1.5
R18
DNP
R20
DNP
R10
0R
QS1
Operation mode of the MMIC
PCB configuration
Ground
Autonomous continuous wave (CW) mode
J1 = 0 Ω
R3 = DNP*
Open
Autonomous pulsed mode
J1 = DNP*
R3 = DNP*
100 kΩ to VDD
SPI mode with external 9.6 MHz clock enabled
J1 = DNP*
R3 = 100 kΩ
VDD (default)
SPI mode
J1 = DNP*
R3 = 0 Ω
*DNP = Do Not Populate/Do Not Place

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Radar MMIC settings configuration
To make the shield work in autonomous mode, you need to remove resistor R3, as shown in Figure 19.
Remove R3 for
autonomous mode
Figure 19 Converting the shield to autonomous mode
Note: Once a BGT60LTR11AIP EBG shield is converted to autonomous mode, it should NOT be connected
to a Radar Baseboard MCU7 to change the settings via the GUI. Only resistor values mentioned in
Table 5 and Table 6 are recommended to be soldered onto the shield to achieve the desired
settings.

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Radar MMIC settings configuration
4.2 Detector threshold
The internal detector threshold is the minimum signal strength that must be reached to trigger a detection
event. The lower the threshold set, the higher the sensitivity and therefore also the detection range.
Note: To avoid triggering false detections, it is recommended to increase the detector threshold, thereby
reducing the sensor sensitivity, especially in “noisy” environments.
Autonomous mode
QS2 is used to select the detector threshold value for autonomous mode. In order to have up to 16 threshold
values, the PLL_TRIG should be connected to VDD by removing R6 and placing R18 = 0 Ω. This will put the MMIC
into “Advance mode”. The default QS2 setting on the shield is for threshold 80.
Recommended resistor values for changing the QS2 on the autonomous shield are detailed in Table 5.
Table 5 QS2 settings
SPI mode
In SPI operation mode, the user can set the internal detector threshold by writing to the thrs (Reg2[12:0]) bit
fields of the MMIC SPI registers.
Resistor settings
Detector threshold
(Radar Fusion GUI setting)
Sensitivity
(Radar GUI setting)
R9
R10
10 kΩ
330 Ω
61
15*
10 kΩ
1 kΩ
66
14*
10 kΩ
1.8 kΩ
80
13
10 kΩ
2.7 kΩ
90
12
10 kΩ
3.9 kΩ
112
11
10 kΩ
5.6 kΩ
136
10
10 kΩ
6.8 kΩ
192
9
10 kΩ
8.2 kΩ
248
8
10 kΩ
12 kΩ
320
7
10 kΩ
15 kΩ
284
6
10 kΩ
18 kΩ
480
5
10 kΩ
27 kΩ
640
4
10 kΩ
39 kΩ
896
3
10 kΩ
56 kΩ
1344
2
10 kΩ
100 kΩ
1920
1
10 kΩ
220 kΩ
2560
0
*High sensitivity levels could lead to false detections and are not shown on the Radar GUI settings.

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BGT60LTR11AIP EBG shield
XENSIV™60 GHz radar system platform
Radar MMIC settings configuration
4.3 Detector hold time
The internal detector hold time is the time for which the internal detector outputs remain active after target
detection.
Autonomous mode
QS3 is used to select the detector hold time value for autonomous mode. In order to have up to 16 hold time
values, “Advance mode” needs to be set, as explained in 4.2. The default QS3 setting on the shield for the hold
time is 1 s. Recommended resistor values for changing the QS3 on the autonomous shield are detailed in
Table 6.
Table 6 QS3 settings
SPI mode
In SPI operation mode, the user can set the internal detector hold time by writing to the hold (Reg10[15:0]) bit
fields of the MMIC SPI registers.
Resistor settings
Detector hold time
R19
R20
10 kΩ
330 Ω
Minimum (16 ms, 32 ms, 64 ms or 128 ms) depending on PRT
10 kΩ
1 kΩ
500 ms
10 kΩ
1.8 kΩ
1 s
10 kΩ
2.7 kΩ
2 s
10 kΩ
3.9 kΩ
3 s
10 kΩ
5.6 kΩ
5 s
10 kΩ
6.8 kΩ
10 s
10 kΩ
8.2 kΩ
30 s
10 kΩ
12 kΩ
45 s
10 kΩ
15 kΩ
1 min.
10 kΩ
18 kΩ
90 s
10 kΩ
27 kΩ
2 min.
10 kΩ
39 kΩ
5 min.
10 kΩ
56 kΩ
10 min.
10 kΩ
100 kΩ
15 min.
10 kΩ
220 kΩ
30 min.