WM71000-NBSD-DA Ramtron, WM71000-NBSD-DA Datasheet - Page 9

• Manufacturer Part Number: WM71000-NBSD-DA
• Description: RFID Transponder AFE Chip (No Memory) Gen-2 RFID Access
• Manufacturer: Ramtron

Specifications of WM71000-NBSD-DA

• Mounting Style: SMD/SMT
• Package / Case: DFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TAG-TO-READER DATA ENCODING
Rev. 1.3
Apr. 2011
The WM710xx supports both encoding formats defined in the Gen2 standard:
Data encoding is performed in the WM710xx as described in the Gen2 standard. A FM0 data symbol is
transmitted with period T which is defined by the tag-to-reader link frequency. The difference between a logic 0
and a logic 1 is defined by an additional mid-bit transition for a logic 0 as shown below in Figure 6. Data
encoding using Miller modulation of a subcarrier (MMS) is further defined by a rate parameter M that defines the
number of link frequency cycles per data bit: 2, 4, or 8, resulting in data encoding defined as MMS2, MMS4, or
MMS8 respectively. MMS data encoding results in a phase inversion of the sub-carrier frequency when one of
the following conditions occurs:
The following set of four figures depicts the data bit values “00”, “01”, “10” and “11” for FM0 and MMS data
encoding formats. The same link frequency is shown for all cases, however the MMS parameter M lengthens the
baseband bit period by 2, 4, or 8 as shown in Figure 7, Figure 8, and Figure 9.
00
01
10
11
00
01
10
11
00
01
10
11
00
01
10
11




0
0
0
0
FM0 baseband (FM0)
Miller modulation of a subcarrier (MMS)
At the mid-bit of a logic 1 data bit, or
At the bit-boundary of two consecutive logic 0s.
T
2T
2T
4T
4T
Figure 7. MMS2 Data Encoding
Figure 8. MMS4 Data Encoding
Figure 9. MMS8 Data Encoding
Figure 6. FM0 Data Encoding
8T
8T
WM710xx – Secure F-RAM with Gen-2 RFID
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