CLRC63201TSLASH0FE datasheet(103/163 Pages) PHILIPS

103 / 163 page

Philips Semiconductors

Product Specification Rev. 3.0; May 2003

Multiple Protocol Contactless Reader IC

CL RC632

103

Confidential

14 RECEIVER CIRCUITRY

14.1 General

The CL RC632 employs an integrated quadrature-demodulation circuit giving the possibility to detect an ISO

14443 compliant subcarrier signal applied to pin RX. The ISO14443-A sub-carrier signal is defined as a

Manchester coded ASK-modulated signal. The ISO14443-B sub-carrier signal is defined as an NRZ-L coded

BPSK modulated ISO14443-B sub-carrier signal.

The quadrature-demodulator uses two different clocks, Q- and

I-clock, with a phase shift of 90° between

them. Both resulting sub-carrier signals are amplified, filtered and forwarded to a correlation circuitry. The

correlation results are evaluated, digitised and passed to the digital circuitry.

For all processing units various adjustments can be made to obtain optimum performance.

14.2 Block Diagram

Figure 14-1 shows the block diagram of the receiver circuitry. The receiving process includes several steps.

First the quadrature demodulation of the carrier signal of 13.56 MHz is done. To achieve an optimum in

performance an automatic clock Q calibration is recommended (see 14.3.1). The demodulated signal is

amplified by an adjustable amplifier. A correlation circuit calculates the degree of similarity between the

expected and the received signal. The bit phase register allows aligning the position of the correlation

intervals with the bit grid of the received signal. In the evaluation and digitizer circuitry the valid bits are

detected and the digital results are send to the FIFO register. Several tuning steps in this circuit are possible.

The user may observe the signal on its way through the receiver as shown in the block diagram above. One

signal at a time may be routed to pin AUX using the TestAnaSelect-Register as described in 21.3.

13.56 MHz

Demodulator

I to Q

Conversion

Q-clock

I-clock

Correlation

Circuitry

VRxFoll

VRxFollQ

VRxAmp

VRxAmpQ

VCorrN

VCorrDQ

VCorrD

VCorrNQ

VEvalL

VEvalR

TestAna

OutSel

Gain[1:0]

Evaluation and Digitizer

Circuitry

s_valid

s_data

s_coll

s_clock

BitPhase[7:0]

MinLevel[3:0]

CollLevel[3:0]

ClockQCalib

ClockQDelay[4:0]

ClockQ180°

clock

RcvClkSel

RxWait[7:0]

Figure 14-1: Block Diagram of Receiver Circuitry

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