AS3930 AMSCO [austriamicrosystems AG], AS3930 Datasheet - Page 19

• Manufacturer Part Number: AS3930
• Description: Single Channel Low Frequency Wakeup Receiver
• Manufacturer: AMSCO [austriamicrosystems AG]

AS3930
Data Sheet - D e t a i l e d D e s c r i p t i o n
In case the maximum amplification at the beginning is a drawback (e.g. in noisy environment) it is possible to set a smaller starting gain on the
amplifier, according to the
Table 14. Bit setting of Gain Reduction
8.4.2 Antenna Damper
The antenna damper allows the chip to deal with higher field strength, it is enabled by register R1<4>. It consists of shunt resistors which
degrade the quality factor of the resonator by reducing the signal at the input of the amplifier. In this way the resonator sees a smaller parallel
resistance (in the band of interest) which degrades its quality factor in order to increase the linear range of the channel amplifier (the amplifier
doesn't saturate in presence of bigger signals).
Table 15. Antenna Damper Bit Setup
8.5 Demodulator / Data Slicer
The performance of the demodulator can be optimized according to bit rate and preamble length as described in
Table 16. Bit setup for Envelop Detector for Different Symbol Rates
www.austriamicrosystems.com/AS3930
R4<3>
0
0
0
0
0
1
1
1
1
R3<2>
0
0
0
0
1
1
1
1
R4<5>
0
0
1
1
R4<2>
0
0
0
1
1
0
0
1
1
Table
R4<1>
14. In this way it is possible to reduce the false frequency detection.
R3<1>
0
0
1
0
1
0
1
0
1
0
0
1
1
0
0
1
1
R4<0>
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
0
1
Table 15
R4<4>
0
1
0
1
shows the bit setup.
R3<0>
0
1
0
1
0
1
0
1
Revision 1.0
Shunt resistor (parallel to the resonator at 125 kHz)
Symbol rate [Manchester symbols/s]
no gain reduction
Gain reduction
-12dB
-16dB
-20dB
-24dB
-4dB
-8dB
n.a.
n.a.
27 kΩ
1 kΩ
3 kΩ
9 kΩ
4096
2184
1490
1130
910
762
655
512
Table 16
and
Table
17.
19 - 33