GSM/GPRS Module
M85 Hardware Design
M85_Hardware_Design Confidential / Released 69 / 92
M85 provides an RF antenna pad for antenna connection. The RF trace in host PCB connected to the
module RF antenna pad should be coplanar waveguide line or microstrip line, whose characteristic
impedance should be close to 50Ω. M85 comes with grounding pads which are next to the antenna pad in
order to give a better grounding. Besides, a ∏ type match circuit is suggested to be used to adjust the RF
performance.
To minimize the loss on the RF trace and RF cable, take design into account carefully. It is recommended
that the insertion loss should meet the following requirements:
GSM850/EGSM900 is <1dB.
DCS1800/PCS1900 is <1.5dB.
4.2. RF Output Power
Table 28: The Module Conducted RF Output Power
In GPRS 4 slots TX mode, the max output power is reduced by 2.5dB. This design conforms to the GSM
specification as described in section
13.16
of
3GPP TS 51.010-1
.
4.3. RF Receiving Sensitivity
Table 29: The Module Conducted RF Receiving Sensitivity
Frequency
Max
Min
GSM850
33dBm ±2dB
5dBm±5dB
EGSM900
33dBm ±2dB
5dBm±5dB
DCS1800
30dBm ±2dB
0dBm±5dB
PCS1900
30dBm ±2dB
0dBm±5dB
Frequency
Receive Sensitivity
GSM850
< -108.5dBm
EGSM900
< -108.5dBm
NOTE
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