MLX90109_06 MELEXIS [Melexis Microelectronic Systems], MLX90109_06 Datasheet - Page 5

• Manufacturer Part Number: MLX90109_06
• Description: 125kHz RFID Transceiver
• Manufacturer: MELEXIS [Melexis Microelectronic Systems]

6 Block Diagram
7 General Description
The oscillator frequency is locked on the antenna resonance frequency. The clock is derived from the
oscillator. In this way, its characteristics are locked to the transmission frequency. As the antenna is used to
determine the carrier frequency, the antenna is always perfectly tuned to resonance. Consequently the
MLX90109 is not sensitive to zero modulation (the so-called “zero modulation” is the phenomena whereby
the tag does modulate properly, but no amplitude modulation can be observed at the reader coil).
The peak detector of the transceiver detects the AM signal generated by the tag. This signal is filtered and
amplified by an on-chip switched capacitor filter before feeding the digital decoder. The same signal is fed
back to close the loop of the antenna voltage.
By setting the SPEED pin to V
The MLX90109 makes an internal first-order filtering of the envelope that changes according to the setting of
the SPEED pin, to fit the Biphase and Manchester data spectrum:
2kbaud (speed pin to V
4kbaud (speed pin to V
3901090109
Rev 008
7.1 Loop Gain Oscillator
7.2 Peak Detector
7.3 Band-Pass Filter
DD
SS
)
)
DD
:
:
or to GND, the filtering characteristics are optimized for either 2 or 4 kbaud.
400Hz to 3.6kHz
800Hz to 7.2kHz
Page 5 of 15
125kHz RFID Transceiver
MLX90109
Data Sheet
Jun/06