VISHAY VITRAMON Ceramic Chip Antenna Application Note EVK 3505 User Guide EVALUATION KIT COMPONENTS The evaluation kit is shown in figure 1. Table 1 details the kit components. The company’s products are covered by one or more of the following: WO2008250262 (A1), US2008303720 (A1), US2008305750 (A1), WO2008154173 (A1). Other patents pending. GENERAL This document is designed to serve as a user guide for the VJ 3505 evaluation kit. It is recommended that this document be read after the following documents were viewed: • VJ 3505 datasheet • VJ 3505 application notes Fig. 1 - Evaluation Kit ITEM Antenna FUNCTIONALITY Ceramic chip antenna. 35 mm by 5 mm by 1.2 mm SMA connector Connect a 50 Ω RF cable to this connector, to get signals received on the antenna end Tuning circuit A digital tuning circuit used to cover the entire UHF band with 2 control pins Dip switch array Used to control the tuning circuit manually. Only pins 2 and 3 (marked D1 and D2) are in use. Pins 1 and 4 are not connected Digital control pins Used to control the tuning circuit electrically. Pins D1 and D2 are standard CMOS level digital control pins capable of supplying at least 1 mA DC connector Used to feed power to the tuning circuit. This connector is used only in the manual tuning alternative set up Document Number: 45188 Revision: 08-Jul-10 For technical questions, contact: [email protected] www.vishay.com 1 APPLICATION NOTE TABLE 1 - KIT COMPONENTS Application Note Vishay Vitramon EVK 3505 User Guide KIT SETUP There are 2 recommended alternative ways to set up the evaluation kit for testing and use. The difference between these alternatives is in the way the tuning circuit is controlled. Both alternatives are described hereafter. SET UP ALTERNATIVE 1 - MANUAL CONTROL In this alternative, the tuning circuit is controlled by the on board mechanical dip switch array. The control line voltage in this setup should be applied to the on board DC connector. A voltage of 2 V to 30 V will ensure good performance. The evaluation kit is supplied with a battery house designed to provide 3 V using two AAA batteries. SET UP ALTERNATIVE 2 - ELECTRICAL CONTROL In this alternative, the tuning circuit is controlled by the 5 pin digital connector. In order to function properly in this alternative and avoid short circuit, the following rules need to be followed: 1. Remove the batteries from the battery housing. 2. Leave all dip switches in L position (in this position, the tuning circuit control pins are in High-Z impedance, and can be controlled by the external pins). 3. Connect the GND pin on the EVK to the common ground used by the external digital control circuit. VJ 3505 VJ 3505 50 Ω RF cable to receiver/ test equipment GND Vcc D1 D2 APPLICATION NOTE Connect control signals and ground to these pins AAA 1.5 V DC feed to circuit H Set All Switches to Low AAA 1.5 V Note that only two of the four switches are active L D3 D2 D1 D3 D2 D1 GND Vcc D1 D2 AAA 1.5 V L H Manual Channel Selection switches. DC Jack can remain connected if batteries were removed AAA 1.5 V 50 Ω RF cable to receiver/ test equipment Fig. 2 - Manual Control Fig. 3 - Electrical Control In set up alternative 1, the tuning circuit is driven and controlled by dip switches D1 and D2. The other two switches in the array are not connected. Maximum current consumed by the tuning circuit is less than 2 mA when operating at 3 V. The 5 pin digital connector is expected to be connected to an external control circuit. The digital control signals D1 and D2 are standard CMOS level signals. A 50 Ω RF cable, connected to the SMA connector, can be used to guide the received signals from the antenna to the desired applicable receiver/test equipment. Note • See table 3 for details regarding channel selection www.vishay.com 2 For technical questions, contact: [email protected] Document Number: 45188 Revision: 08-Jul-10 Application Note Vishay Vitramon EVK 3505 User Guide CONTROL SIGNAL INTEGRITY Table 2 describes the desired control signal properties: TABLE 2 - SIGNAL INTEGRITY FOR ELECTRICAL CONTROL ALTERNATIVE PARAMETER SYMBOL MIN. TYP. MAX. UNITS COMMENTS Equivalent DC Circuit 1 kΩ Logical LOW Vil - 0.3 0 0.2 V 1 kΩ Logical HIGH Vih 2 3 5 V Sink current Isink 0 0.01 0.05 mA Vin = - 0.3 V This is diode reverse leakage current Isource 4 4.2 5 mA Vin = 5 V Source current OPERATING THE KIT To properly operate the kit, the antenna needs to be tuned to the required band. The kit is offering coverage of the entire UHF band, by dividing it into 4 sub-bands. Selecting the correct band is critical for antenna performance. For technical questions, contact: [email protected] www.vishay.com 3 APPLICATION NOTE Document Number: 45188 Revision: 08-Jul-10 Application Note Vishay Vitramon EVK 3505 User Guide CHANNEL CHARACTERISTICS The two digital control lines offer four frequency channels as described in the table 3 below. This table shows the typical peak gain obtained in each of the four channels. TABLE 3 - TUNING CIRCUIT BANDS CHANNEL D1 D2 BAND (MHz) S11 (dB) 460 5 560 660 760 860 760 860 760 860 760 860 0 -5 1 H L 470 to 540 - 10 - 15 - 20 - 25 460 5 f (MHz) 560 660 0 -5 2 l L 540 to 620 - 10 - 15 - 20 - 25 460 5 f (MHz) 560 660 0 -5 3 H H 620 to 750 - 10 - 15 - 20 - 25 APPLICATION NOTE 460 5 f (MHz) 560 660 0 -5 4 l h 750 to 860 - 10 - 15 - 20 - 25 f (MHz) Comment: The EVK tuning circuit is optimized to cover the band of 474 MHz to 800 MHz. There is an alternative tuning circuit available, to cover the band of 474 MHz to 860 MHz. For more information see 'VJ 3505 application notes - tuning circuit'. www.vishay.com 4 For technical questions, contact: [email protected] Document Number: 45188 Revision: 08-Jul-10 Application Note Vishay Vitramon EVK 3505 User Guide VJ 3505 EVALUATION KIT ANTENNA PERFORMANCE MEASURED PEAK GAIN AND EFFICIENCY The Antenna radiation characteristics are influenced by several factors including ground plane dimensions and impedance matching network. The antenna parameters presented hereafter were measured using to the configuration suggested by the VJ 3505 evaluation board. Figure 4 shows radiation patterns of the EVK 3505 in various frequencies across the UHF band: Performance - Radiation Patterns (VJ 6040) 0 330 30 0 - 10 - 10 - 20 300 60 - 20 - 30 - 30 -4 0 - 50 270 - 40 90 - 50 500 MHz 600 MHz 700 MHz 862 MHz 240 500 MHz 600 MHz 700 MHz 800 MHz 120 150 210 180 Fig. 4 - Peak Gain vs. Frequency Applications that do not require full coverage of the UHF band can enjoy additional efficiency by removing the tuning circuit. In this case the antenna can be fixed to any 150 MHz band within the UHF range. Figure 5 shows simulated peak gain and radiation efficiency of the VJ 3505 antenna over frequency throughout the UHF band, compared with the MBRAI requirements: VJ 3505 Simulated Antenna Parameters 2 -2 -4 -6 Peak Gain Radiation Efficiency MBRAI -8 - 10 - 12 470 520 570 620 670 720 770 820 870 Frequency (MHz) Fig. 5 - Simulated Radiation Efficiency and Peak gain vs. Frequency Document Number: 45188 Revision: 08-Jul-10 For technical questions, contact: [email protected] www.vishay.com 5 APPLICATION NOTE Radiation Efficiency (dB) 0 Application Note Vishay Vitramon EVK 3505 User Guide SCHEMATIC DRAWING Figure 6 below shows the schematic drawing of the evaluation kit. See tuning circuit application note for details regarding recommended BOM. VJ 3505 C6 L1 L3 R1 Digital Input 1 D1 D1 C1 L4 R2 D2 L2 L5 R3 Digital Input 2 D2 C4 C5 C7 C2 Dip Switch 50 Ω RF feed VCC DC Jack D1 D2 APPLICATION NOTE Fig. 6 - EVK 3505 Schematic TABLE 4 - EVK3505 BOM LIST VALUE Antenna 120 nH PIN diode 27 nH 39 nH 3.3 pF 2.2 pF 220 pF 1 kΩ 0Ω REFERENCE VJ 3505 l3, l4, l5 D1, D2 L1 L2 C1 C5 C2, C4, C6, C7 R1, R3 R2 QUANTITY PER CIRCUIT PART NUMBER 1 VJ3505M011SXMSRA0 3 HK1005R12J-T 2 BAR63-02V 1 IMC0402ER27NJ 1 IMC0402ER39NJ 1 VJ0402A3R3BXACW1BC 1 VJ0402A2R2BXACW1BC 4 VJ0402A221JXACW1BC 2 CRCW1KJNED 1 CRCW0R0Z0ED MANUFACTURER Vishay Taiyo Yuden Infineon Vishay Vishay Vishay Vishay Vishay Vishay Vishay Features are subject to revisions or changes without notification www.vishay.com 6 For technical questions, contact: [email protected] Document Number: 45188 Revision: 08-Jul-10 Application Note Vishay Vitramon EVK 3505 User Guide ELECTRICAL CHARACTERISTICS AND FUNCTIONAL DESCRIPTION The tuning circuit herein is effectively an inductor, connected in series with a capacitor. The total impedance generated by this circuit can be described in the following equation (excluding the capacitors C2, C3 and C4): Z = Z L + Z C + Z L = j * (ω L 1 − 1 1 2 ω = 2π f 1 ω C1 + ω L 2) By connecting PIN diodes in parallel to C1 and L2, the tuning circuit can electrically short-circuit one of the two reactants or both. Table 2 is detailing all logical states of the tuning circuit, and the electrical effect as presented in the impedance Z. For the sake of small signal analysis, when the PIN diode is in forward conductance mode, it is represented as a 2 Ω resistor. TABLE 5 - TUNING CIRCUITS' IMPEDANCES DIGITAL INPUT 1 DIGITAL INPUT 2 PIN 0 PIN 1 0 0 High Z High Z 0 1 High Z Z (W) j * ( ω L1 − 2Ω 1 ω C1 j * ( ω L1 − + ω L2 ) 1 )+ 2 ω C1 1 0 2Ω High Z j * ( ω L1 + ω L2 ) + 2 1 1 2Ω 2Ω j * ω L1 + 4 As evident from table 2, each one of the 4 possible logic states represents a different tuning circuit between the antenna and the receiver port. By applying the values shown in table 1 to L1, C1 and L2 the 4 states cover the entire UHF band. SELECTING THE RESISTIVE VALUES OF R R1 resistor is used to DC bias the PIN diodes. Selecting the value for R1 can be derived for the following equation: Vcontrol - Vd Id Let's assume that the digital control line is 1.8 V when high. To allow a current of 1 mA, R1 should be set as follows: When: R = resistive value (in Ω) for R1 Vcontrol = control voltage (in volts) as generated by the controller Vd = forward voltage (in V) generated on the PIN diode when biased R1 = 1 .8 - 0 .8 = 1 kΩ 0 . 001 Id = forward current (in A) through the PIN diode when biased Document Number: 45188 Revision: 08-Jul-10 For technical questions, contact: [email protected] www.vishay.com 7 APPLICATION NOTE R = Example: The PIN diode should be forward biased at 0.8 V to allow just over 1 mA to pass through it (see the graphs below). At 1 mA, the diode small signal impedance drops to its required value of 2 Ω. Application Note Vishay Vitramon EVK 3505 User Guide 6 100.00 f = 100 MHz RF- Forward Resistance (Ω) I F - Forward Current (mA) 5 10.00 1.00 0.10 4 3 2 1 0.01 0 0.5 18325 0.6 0.7 0.8 0.9 1.0 0.1 VF - Forward Voltage (V) 10 1.0 18341_1 100 IF - Forward Current (mA) Fig. 7 - PIN Diode Characteristics GROUND PLANE CONFIGURATION General APPLICATION NOTE 5 mm VISHAY VJ 3505 Tuning Circuit 85 mm Receiver 72 mm VJ 3505 evaluation board demonstrates exceptional antenna performance achieved with a 40 mm by 80 mm ground plane. 35 mm 3 mm An important consideration in the design of this product into cell phone applications is the coexistence of the cell phone antenna with VJ 3505. The recommended ground plane configuration presented below includes recommendations regarding how to set the cellular antenna relative to the VJ 3505 to minimize losses to both antennas. 40 mm 50 Ohm The VJ 3505 antenna is unbalanced, therefore requiring a ground plane for its operation. The ground plane dimensions significantly influence the antenna performance. The rule of thumb in unbalanced antenna ground plane design is that antenna efficiency increases with ground plane size. The evaluation board demonstrates how the antenna complies with the EMBRAI standard when set against a ground plane small enough to fit into most cellular phone designs. Applications that allow larger ground planes can enjoy higher efficiency. Figure 4 describes a recommended reference ground plane configuration. The areas marked in green in the close proximity to the antenna should remain empty from large conducting surfaces including ground planes (outer or inner layers), batteries, connectors, buttons, or other large components. Applications that require additional antennas, such as cell phones, should position the cellular antenna at the top left hand side while maintaining maximum distance from VJ 3505. The presence of an additional antenna might cause loss of efficiency to both antennas. www.vishay.com 8 Fig. 8 - Recommended Ground Plane For technical questions, contact: [email protected] Document Number: 45188 Revision: 08-Jul-10