Application Note
page 9 of 33
V1.7
2022-08-01
XENSIV™ BGT60LTR11AIP shield
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 supply
Since radar sensors are very sensitive to supply voltage fluctuations or cross-talk between different supply
domains, a low-noise power supply as well as properly decoupled supply rails are vital. The Radar Baseboard
MCU7 provides a low-noise supply. Figure 8 depicts the schematics of the low-pass filters employed to decouple
the supplies of the different power rails in the BGT60LTR11AIP 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 low-pass filter, which provides better decoupling for lower frequencies.
Figure 8
Schematics of the sensor supply and low-pass filters
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 saves current consumption, as crystal oscillators
consume only a few milliamperes (mA) and run continuously. The BGT60LTR11AIP shield uses a 38.4 MHz
crystal oscillator, as shown in Figure 9.
1V5Sensor
1V8Sensor
L1
MMZ0603S121HT000
Vin
VDD_RF
3V3Sensor
1V5_LDO
L3
DNP
GND
2
OUT
1
IN
4
EN
3
E
P
A
D
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
