SLOS758G December 2011 – March 2020 TRF7963A
The first gain and filtering stage has a nominal gain of 15 dB with an adjustable band-pass filter. The band-pass filter has programmable 3-dB corner frequencies from 110 kHz to 450 kHz for the high-pass filter and from 570 kHz to 1500 kHz for the low-pass filter. After the band-pass filter, there is another gain-and-filtering stage with a nominal gain of 8 dB and with frequency characteristics identical to the first band-pass stage.
The internal filters are configured automatically depending on the selected ISO communication standard in the ISO Control register (address 0x01). If required, additional fine tuning can be done by writing directly to the RX special setting registers (address 0x0A).
Table 6-4 shows the various settings for the receiver analog section. Setting B4, B5, B6, and B7 to 0 results in a band-pass characteristic of 240 kHz to 1.4 MHz, which is appropriate for ISO/IEC 14443 B data rate of 106 kbps, ISO/IEC 14443 A or B data rates of 212 kbps and 424 kbps, and FeliCa data rate of 424 kbps.
|B7||Band-pass filter from 110 kHz to 570 kHz||Appropriate for any 212-kHz subcarrier systems like FeliCa|
|B6||Band-pass filter from 200 kHz to 900 kHz|
|B5||Band-pass filter from 450 kHz to 1.5 MHz||Appropriate for Manchester-coded 106-kbps 848-kHz subcarrier systems (for example, used in ISO/IEC 14443 A).|
|B4||Band-pass filter from 100 kHz to 1.5 MHz||Appropriate for highest bit rate (848 kbps) used in high-bit-rate ISO/IEC 14443 B. Gain is reduced by 7 dB.|
|B3||00 = No gain reduction
01 = Gain reduction for 5 dB
10 = Gain reduction for 10 dB
11 = Gain reduction for 15 dB
|Sets the RX digital gain reduction (changing the window of the digitizing comparator).|