Product Info

Description of proximity sensor Techniques
The proximity sensor is triggered by capacitance changes due to objects in the vicinity of the
sensing element.
Capacitive proximity sensor sharea metallic electrode with the GSM、WCDMA and LTE
antenna radiator. The metallic electrode and sar sensor chip works as a sensor. As is
shown in Figure 2.
The proximity sensor or the power reduction cannot be intentionally or unintentionally
turned-off by the user.
The expected capacitance trigger values are programmed in each device for each power
back-off stage. Capacitance trigger value is C1
When a certain object or human body approaches the DUT, if the measured capacitance
is lower than C1, proximity sensor is not triggered. If the measured capacitance is equal to
C1 or higher than C1, the power back-off is triggered.
Power Reduction operation table
The phone use Qualcomm platform, which have some special NVs for SAR related max
power back off, These NVs are used to set a new max power limit based proximity
information and call configuration. When human body is in proximity and is detected by
sensor, a new max power limit is set using the values stored in the NV. If Base station
requests the higher output power above the limit, the power control algorithm inside
modem chip will limit the power up to the preset power limit. If base station requests a
lower output power less than the limit, the out power is controlled by base station.
4 proximity sensor coverage, distance and angle
Band
Test position
Sensor Trigger
Distance
range(DUT to
Phantom)
Power
reduction
amount(dB)
Target
Power
level
（dBm）
WCDMA
B1
Extremity
SAR(Bottom/Front/Back/Left)
held by hand
0mm
2
21
Top side
ALL
0
23