·         Operational Amplifier

If you have signal inputs (AC/DC) and need to be amplified, you can pick an operational amplifier (Op Amp).  Operational amplifiers are very versatile electronic devices. This is a sampling of the kinds of devices which can be created with a single op-amp. Figure 1 shows an Op Amp symbol.

Figure 1 Op Amp Symbol

Basically, there are two types of Operational Amplifier. 

1.        Inverting Amplifier

For an ideal op-amp, the inverting amplifier gain is given simply by :

Note:

R_i              : Resistor Input

R_f             : Resistor feedback

V_in            : Voltage Input

V_out          : Voltage Output

Figure 2. Inverting Amplifier Circuit

 Figure 3. Signal output inverted with inverting op amp

Sign “-“ in the equation means output signal is inverted from input signal, shown in figure 3. For equal resistors, it has a gain of -1, and is used in digital circuits as an inverting buffer.

2.        Non Inverting Amplifier

For an ideal op-amp, the non-inverting amplifier gain is given by

Figure. 4 Non Inverting Amplifier Circuit

Introduction to Smart Cards

A smart card is a plastic card (dimension 85.6mm x 53.98mm x 0.76mm) that contains an embedded computer chip (either a memory or microprocessor type) that stores and transacts data. This data is usually associated with either value, information, or both and is stored and processed within the card's chip. The card data is transacted via a reader that is part of a computing system. 

Figure 1. Smart Cards

Smart cards are defined according to how the card data is read/written and the type of chip implanted within the card and its capabilities. Figure 2 shows classification smart cards according to chip cards implanted.

Figure 2. Classifications smart cards

The ISO Standard (7816-2) defined eight contacts but only 6 are actually used to communicate with the outside World. Figure 3 shows contact card pin configurations.

Figure 3. The Contact Card Pins Configuration.

Each pin is assigned to

·         C1: supply power input (VCC).

There are 3 three classes of operating conditions, based on the nominal supply voltage provided to the card.

§  5 V for class A.

§  3 V for class B. (our card is of type B)

§  1,8 V for class C.

·         C2: reset signal input (RST).

·         C3: clock signal input (CLK).

This contact is used to provide the card with clock signal. The actual value of the frequency of the clock signal is denoted f. The minimum value shall be 1 MHz.  

·        C5: ground (GND, reference voltage).

·         C6: standard or proprietary use (VPP).

This contact is available for either standard or proprietary use, as input and/or output.   

·         C7: input/output for serial data (I/O).

This contact is used as input (reception mode) or output (transmission mode). The information exchange uses two states of the electrical circuit as follows:

A.      State H if the card and the interface device are in reception mode or if the transmitter imposes this state.

B.      State L if the transmitter imposes this state.

Systems that are enhanced with smart cards are in use today throughout several key applications, including health care, banking, entertainment, and transportation. All applications can benefit from the added features and security that smart cards provide.