CLRC63201TSLASH0FE datasheet(140/163 Pages) PHILIPS

140 / 163 page

Philips Semiconductors

Product Specification Rev. 3.0; May 2003

Multiple Protocol Contactless Reader IC

CL RC632

140

Confidential

20.2 Circuit Description

The matching circuit consists of an EMC low pass filter (L0 and C0), a matching circuitry (C1 and C2), and a

receiving circuit (R1, R2, C3 and C4), and the antenna itself.

For more detailed information about designing and tuning an antenna please refer to the Application Note

’MIFARE and I CODE MICORE reader IC family; Directly Matched Antenna Design’ and

‘MIFARE (14443A) 13,56 MHz RFID Proximity Antennas’.

20.2.1 EMC LOW PASS FILTER

The MIFARE system operates at a frequency of 13.56 MHz. This frequency is generated by a quartz

oscillator to clock the CL RC632 and is also the basis for driving the antenna with the 13.56 MHz energy

carrier. This will not only cause emitted power at 13.56 MHz but will also emit power at higher harmonics.

The international EMC regulations define the amplitude of the emitted power in a broad frequency range.

Thus, an appropriate filtering of the output signal is necessary to fulfil these regulations.

A multi-layer board it is recommended to implement a low pass filter as shown in the circuit above. The low

pass filter consists of the components L0 and C0. The recommended values are given in the above

mentioned application notes.

Note: To achieve best performance all components shall have at least the quality of the recommended ones.

Note: The layout has a major influence on the overall performance of the filter.

20.2.2 ANTENNA MATCHING

Due to the impedance transformation of the given low pass filter, the antenna coil has to be matched to a

certain impedance. The matching elements C1 and C2 can be estimated and have to be fine tuned

depending on the design of the antenna coil.

The correct impedance matching is important to provide the optimum performance. The overall Quality factor

has to be considered to guarantee a proper ISO14443 communication scheme. Environmental influences

have to considered as well as common EMC design rules.

For details refer to the above mentioned application notes.

Note: Do not exceed the current limits ITVDD, otherwise the chip might be destroyed.

Note: The overall 13.56MHz RFID proximity antenna design with the CL RC632 chip is straight forward and

doesn’t require a special RF-know how. However, all relevant parameters have to be considered to

guarantee an overall optimum performance together with international EMC compliance.

CLRC63201T/0FE Datasheet(PDF) 140 Page - NXP Semiconductors