a leap ahead in analog

Transcription

1 EMV Contactless Payment Systems based on AS3911 Overview and System Simulations Giuliano Manzi, PhD Mannheim, May 23 25, 2012 CST EUROPEAN USER CONFERENCE 2012 a leap ahead in analog

2 OUTLINE AS3911 OVERVIEW EMVCo OVERVIEW EMVCo History and Today EMV Contactless Specifications for Payment Systems Standard Reference PICC and PCD Analog / Signal RF Requirements Simulation Model Reference PICC PCD Reference System Simulations and Validation RF Power Validation (Simulations vs. Measurements) RF Signal Overview EMVCo System Modeling austraimicrosystems EMVco Reference Design 2

3 AS3911 OVERVIEW The AS3911 is a highly integrated NFC Initiator / HF Reader IC. It includes the analog front end (AFE) and a highly integrated data framing system for ISO (NFCIP-1) initiator, ISO (NFCIP-1) active target, ISO A and B reader (including high bit rates) and Felica reader. Implementation of other standard and custom protocols is possible through using the AFE and implementing framing in the external microcontroller (Transparent mode). The AS3911 includes several features, such as low power capacitive sensor, which can be used to detect a presence of a card without switching on the reader field. Additionally, a presence of a card can be detected by performing a measurement of amplitude or phase of signal on antenna LC tank and comparing it to stored reference. The AS3911 is also qualified for use in automotive applications which makes it ideal for car access, ignition and diagnostic functions. The AS3911 is designed for operation from wide power supply range from 2.4V to 5.5V, peripheral interface IO pins support power supply range from 1.65V to 5.5V. Applications The AS3911 is suitable for a wide range of applications including EMV Payment, Access Control, Automotive, NFC Infrastructure, andticketing. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 3

4 AS3911 Unique Features Antenna Tuning Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, Resonance increase the current that is flowing through the coil. AS391x optimize the resonance Optimized resonance behavior will maximize current Advantage: antenna management make the system independent of parameter variances Capacitive Wake-up Minimum 800 ms: 2,0 µa Typical 100ms: 4,7µA Fast 10ms: 31 µa Advantage: lowest current consumption enables Battery powered system 4

5 EMVCo History and Today The EMV name comes from Europay, MasterCard and Visa, the companies that in 1994 initiated development of the EMV Specifications. Europay International SA became part of MasterCard in JCB joined EMVCo in 2004, and American Express in At the time, many banks recognized the benefits of chip-based payment but also realized that international standards for such payment were needed to help foster global interoperability. The EMV Specifications were created to fill that void. The first version of the EMV Specifications was published in 1996, as version The most recent version, EMV 4.2, was published in June Today EMVCo manages, maintains and enhances the EMV Integrated Circuit Card Specifications to help facilitate global interoperability and compatibility of payment system integrated circuit cards and acceptance devices. EMVCo maintains and extends specifications, provides testing methodology and oversees the testing and approval process. EMV chip-based payment card systems are now utilized in numerous countries around the world. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 5

6 EMVCo DEFINITION The basic components of a contactless system are the contactless reader or Proximity Coupling Device (PCD) and a transponder or Proximity IC Card (PICC). The PCD is an antenna connected to an electronic circuit. The PICC consists of an inductive antenna and an integrated circuit connected to the ends of the antenna. The combination PCD PICC behaves like a transformer. An alternating current passes through a primary coil (PCD antenna) and creates an electromagnetic field, which induces a current in the secondary coil (PICC antenna). The PICC converts the electromagnetic field (or RF field) transmitted by the PCD, into a DC voltage by means of a diode rectifier to power the PICC s internal circuits. The configuration and tuning of both antennas determines the coupling efficiency from one device to the other. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 6

7 EMVCo DEFINITION The RF energy transmitted by the PCD and received by the PICC not only powers up the PICC but is also used to transport the data through modulation of the carrier. The PICC decodes and processes the data and responds to the PCD by means of load modulation. Load modulation is based on the electromagnetic coupling (i.e. mutual inductance) between PICC and PCD similar to the power transfer and communication from PCD to PICC. The PICC changes the current in its antenna. The current variation in the PICC antenna is sensed by the PCD as a small change in the current in its antenna, typically sensed as a small increase in voltage across a resistor in series with the PCD antenna. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 7

8 EMVCo REFERENCE SYSTEM Why a Reference System is needed? The RF power and signal interface part of the specification is specified in terms of the EMVCo reference equipment. EMVCo reference equipment consists of an EMVCo reference PCD, an EMVCo reference PICC and an EMVCo reference CMR (Common Mode Rejection). The purpose of the EMVCo reference equipment is to provide a PCD and PICC that cover the variations in contactless technology. A PCD can therefore be checked against the EMVCo Reference PICC and a PICC can be checked against the EMVCo Reference PCD. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 8

9 EMVCo REFERENCE SYSTEM The Reference PCD has a circular antenna of about 7 cm, which is in the small range of antenna sizes encountered in EMVCo terminals. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, Customer Trend is to have smaller and smaller PCD antennas The circular antenna creates a symmetric field distribution from the z-axis, which simplifies measurements. When fed with 600 mw into its 50 Ω input impedance at resonance, the EMVCo Reference PCD provides a magnetic field which is representative of most PCDs. 9

10 EMVCo REFERENCE SYSTEM The EMVCo Reference PICC has an antenna similar to those found in ID-1 cards. (64 mm x 34 mm) As payment products based on this specification the system is designed to work with only one PICC in the PCD field and PICC it is tuned to 16.1 MHz. This is a compromise between power consumption, detuning and communication capability. The EMVCo Reference PICC allows the analysis of the signal as sent out by a PCD. For analyzing the frequency content of these signals, it is equipped with a pickup coil, which is an integral part of the EMVCo Reference PICC. The EMVCo Reference PICC can also send information back to a PCD, using various levels of load modulation. The EMVCo Reference PICC can be configured with a linear and a non linear load. The non linear load is self-adapting to the magnetic field strength. The (variable) load parameters are set based on the maximum power consumption in current contactless cards. The maximum power consumption represents a worst case scenario for a PCD. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 10

11 EMVCo OPERATING VOLUME The Operating Volume of a PCD is the 3-dimensional space for which the specification imposes requirements on the magnetic field H OV (Operating Field). Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, The Operating Volume is measured from the centre of the landing plane, along an axis perpendicular to the landing plane. Requirements on this geometry suppose that the PCD is stationary and that the PICC moves slowly (less than 1 m/s) through the Operating Volume. 11

12 EMVCo RF Requirements RF signal power Envelope shaping PCD to PICC Envelope shaping PICC to PDC 12

13 EMVCo RF Requirements RF signal power 13

14 EMVCo PCD to PICC The ISO/IEC standard defines two possible modulation types, called Type A and Type B. For communication from PCD to PICC, both Type A and Type B use Amplitude Shift Keying (ASK). The amplitude of the carrier is switched between V 1 and V 2, creating a lower level when the field is at value V 2. The requirements of the lower level as well as of the envelope of the carrier for the two modulation types of ISO/IEC are defined in this section. Type A communication from PCD to PICC uses the modulation principle of ASK 100%. The carrier is turned on and off, creating a lower level when turned off. In practice, it will result in a modulation depth of 95% or higher. The lower level for Type A modulation is referred to as pause by ISO/IEC Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 14

15 EMVCo PCD signal shaping PCD to PICC Type-A The PCD shall modulate the Operating Field in the Operating Volume in such a way that the signal measured at the output of the pickup coil of the EMVCo Reference PICC has the following characteristics: The time between V 4 of the falling edge and V 2 of the rising edge shall be t 1. If V does not decrease monotonically from V 4 to V 2, the time between a local maximum and the time of passing the same value before the local maximum shall be t5. This shall only apply if the local maximum is greater than V 2. Ringing following the falling edge shall remain below V OU,A V 1. V shall remain less than V 2 for a time t2. V shall increase monotonically to V 3 in a time t 4. V shall increase monotonically to V 4 in a time t 3. Overshoots immediately following the rising edge shall remain within (1±V OU,A )V 1. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 15

16 EMVCo PCD to PICC PCD signal shaping Type-B The PCD shall modulate the Operating Field in the Operating Volume in such a way that the signal measured at the output of the pickup coil of the EMVCo Reference PICC has the following characteristics: The modulation index (m i ) of the signal shall be mod i. V shall decrease monotonically from V 3 to V 4 (i.e. the falling edge) in a time t f. V shall increase monotonically from V 4 to V 3 (i.e. the rising edge) in a time t r. The rising and falling edges of the modulation shall be monotonic. Overshoots and undershoots following the falling and rising edge shall be less than V OU,B (V 1 -V 2 ). Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 16

17 EMVCo PICC to PCD Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, PICC signal shaping For the communication from PICC to PCD, both Type A and Type B use load modulation. The carrier frequency f c is used to derive a subcarrier with frequency f s equal to f c /16 (~847 khz). Switching a load on and off at this frequency creates the subcarrier. When the PICC is in the loaded state, a higher current will flow through the antenna of the PICC than in the case where the load is not switched on. This difference in current in the PICC antenna is sensed by the PCD. 17

18 EMVCo PICC to PCD PICC signal shaping For the communication from PICC to PCD, both Type A and Type B use load modulation. The carrier frequency f c is used to derive a subcarrier with frequency f s equal to f c /16 (~847 khz). Switching a load on and off at this frequency creates the subcarrier. When the PICC is in the loaded state, a higher current will flow through the antenna of the PICC than in the case where the load is not switched on. This difference in current in the PICC antenna is sensed by the PCD. Type A modulates the subcarrier using On-Off Keying (OOK). Type B modulates the subcarrier using Binary Phase Shift Keying (BPSK). BPSK uses two signal phases: 0 degrees and 180 degrees. If the phase of the wave does not change with regard to a reference phase, then the signal state stays the same (low or high). If the phase of the wave changes by 180 degrees (i.e. the phase reverses) then the signal state changes. The reference phase is referred to as Ø0. Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, 18

19 Mesaurement POINTS 19

20 SIMULATIONS 20 SIMULATIONS Reference PICC PCD

21 SIMULATIONS PICC MW Studio FEM solver DS Studio S-Parameter Analysis 21

22 SIMULATIONS PCD Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, DS Studio S-Parameter Analysis MW Studio FEM solver 22

23 SYSTEM SIMULATIONS SIMULATION MODEL VALIDATION (vs. measurements) 23

24 SYSTEM SIMULATIONS Simulation sweep of distance D from 15mm to 45mm sweep of input signal from 3Vpp to 5Vpp different configuration PINs at J7 (1-2;1-3;1-4;1-5) Hardware used during measurements: - PAYPASS reference PICC Antenna (Version 2.1) - Reference PCD (A01-088) 24

25 SYSTEM SIMULATIONS CST MW Studio 3D model D 25

26 SYSTEM SIMULATIONS Copyright 2011, austriamicrosystems AG. All rights reserved. The material herein may not be reproduced, adapted, merged, PCD PICC Physical model (3DEM) PCD circuitry PICC circuitry (w/o Modulation and external noise) Example of simulation results DS TD-analysis 26

27 SYSTEM SIMULATIONS (RF Power Validation) Measurements vs Simulation differents PICC Setting) NOTE: 15m: Measurements data at D = 15mm 15s: Simulation data at D = 15mm 27

28 SYSETM SIMULATIONS (Example of Signal) Example of simulated signal at the pick-up coil 28

29 REAL SYSTEM SIMULATIONS 29

30 REAL SYSTEM SIMULATIONS PCD to PICC Signal (Type A) 30

31 REAL SYSTEM SIMULATIONS PCD to PICC Signal (Type B) 31

32 CONCLUSION EMV contactless equivalent system model developed. Good agreement between simulations and measurements in simulation of: RF power level Time domain behavior of the signal Model can be used to optimize and fine tune any EMV Contactless system. 32

33 Reference Design 33

34 Reference Design Sim 4.9 V Meas 5 V 34 Sim 2.5 V Meas 2.7 V

35 Reference Design 35