AntennaGuard 0402/0603 AVX Low Capacitance Multilayer Varistors ESD Protection for Antennas and Low Capacitor Loading Applications GENERAL DESCRIPTION AVX’s 0402/0603 AntennaGuard products are an ultra-low capacitance extension of the proven TransGuard® TVS (transient voltage suppression) line of multilayer varistors. RF designers now have a single chip option over conventional protection methods (passive filters with diode clamps), which not only gives superior performance over traditional schemes, but also provides the added benefits of reduced PCB real estate and lower installation costs. AVX’s AntennaGuard products are available in capacitance ratings of ≤3pF (0402 & 0603 chips), 2 and 12pF (0603 chip). These low capacitance values have low insertion loss, as well as give other TransGuard ® advantages such as small size, sub-nanosecond response time, low leakage currents and unsurpassed reliability (FIT Rate of 0.2) compared to diodes. RF antenna/RF amplifier protection against ESD events is a growing concern of RF circuit designers today, given the combination of increased signal “gain” demands, coupled with the required downsizing of the transistor package. The ability to achieve both objectives is tied to a reduced thickness of the SiO 2 gate insulator layer within the semiconductor. The corresponding result of such a change increases the Power Amplifier’s (PA’s) vulnerability to ESD strikes — a common event with handheld electronic products with RF transmitting and/or receiving features. AVX Low Capacitance AG Series parts are ideal solution for this type of applications as well as for many more where low capacitance ESD protection is needed. GENERAL CHARACTERISTICS • Operting Teperature: -55°C to +125°C • Working Voltage: ≤18Vdc • Case Size: 0402, 0603 FEATURES APPLICATIONS • Smallest TVS Component • Single Chip Solution • Low Insertion Loss • Fastest Response Time to ESD Strikes • Capacitance: 2, 3 and 12pF • RF Amplifiers • Antennas • Laser Drivers • Sensors • Radars • RFID • Keyless entry • Near fileld communication • Datalines • Capacitance sensitive applications and more HOW TO ORDER VC 04 AG 18 Varistor Chip Size Varistor Series Working Chip 04 = 0402 AntennaGuard Voltage 06 = 0603 (DC) 3R0 Y A Capacitance Non-Std. Not 2pF = 2R0 Cap Applicable 3pF = 3R0 Tolerance 12pF = 120 C = ±0.25pF (2R0) Y = Max (3R0) Y = +4, -2pF (120) T x Termination T = Ni/Sn (Plated) Reel Size 1 = 7" 3 = 13" W = 7" (0402 only) x Reel Quantity A = 4,000 or 10,000 (i.e., 1A = 4,000 3A = 10,000) WA = 10,000 47 AntennaGuard 0402/0603 AVX Low Capacitance Multilayer Varistors ESD Protection for Antennas and Low Capacitor Loading Applications ANTENNAGUARD CATALOG PART NUMBERS/ELECTRICAL VALUES AVX Part Number VW (DC) VW (AC) IL Cap Cap Tolerance Case Size VC04AG183R0YAT_ _ VC06AG182R0CAT_ _ VC06AG183R0YAT_ _ VC06AG18120YAT_ _ ≤ 18 ≤ 18 ≤ 18 ≤ 18 ≤ 14 ≤ 14 ≤ 14 ≤ 14 0.1 0.1 0.1 0.1 3 2 3 12 Max ±0.25pF Max +4, -2pF 0402 0603 0603 0603 Termination Finish Code Packaging Code VW (DC) VW (AC) IL Cap DC Working Voltage (V) AC Working Voltage (V) Maximum Leakage Current at the Working Voltage (μA) Maximum Capacitance (pF) @ 1 MHz and 0.5 Vrms; VC06AG18120YAT capacitance tolerance: +4, -2pF PHYSICAL DIMENSIONS mm (inches) W L Size (EIA) T 0402 0603 t Length (L) 1.00±0.10 (0.040±0.004) 1.60±0.15 (0.063±0.006) Width (W) 0.50±0.10 (0.020±0.004) 0.80±0.15 (0.031±0.006) Max Thickness (T) 0.60 (0.024) 0.90 (0.035) Land Length (t) 0.25±0.15 (0.010±0.006) 0.35±0.15 (0.014±0.006) SOLDERING PAD DIMENSIONS D mm (inches) A C 48 B Suppression Device AVX 0402 AVX 0603 A 1.70 (0.067) 2.54 (0.100) Pad Dimensions B C 0.61 (0.024) 0.51 (0.020) 0.89 (0.035) 0.76 (0.030) D 0.61 (0.024) 0.89 (0.035) AntennaGuard 0402/0603 AVX Low Capacitance Multilayer Varistors ESD Protection for Antennas and Low Capacitor Loading Applications Antenna Varistors AVX offers a series of 0402 and 0603 chip varistors, designated the AntennaGuard series, for RF antenna/RF amplifier protection. These devices offer ultra-low capacitance (<3pF in 0402 chips, and ≤3pF & ≤12pF in 0603 packages), as well as low insertion loss. Antenna varistors can replace output capacitors and provide ESD suppression in cell phones, pagers and wireless LANs. It is very common to employ some form of a FET in many types of efficient/miniature RF amplifiers. Typically, these RF transistors have nearly ideal input gate impedance and outstanding noise figures. However, FETs are very susceptible to ESD damage due to the very thin layer of SiO2 uses as the gate insulator. The ultra-thin SiO2 layer is required to improve the gain of the transistor. In other words, the upside of the performance enhancement becomes the downside of the transistors survival when subjected to an ESD event. ESD damage to the RF Field Effect Transistors (FETs) is a growing concern among RF designers due to the following trends: (1) RF amplifiers continue to shrink in size, and (2) FET gains figures continue to increase. Both trends relate to decreasing gate oxide thickness, which in turn, is directly proportional to increased ESD sensitivity. As miniaturization trends accelerate, the traditional methods to protect against ESD damage (i.e., PC board layout, passive filters, and diode clamps) are becoming less and less effective. AVX’s AntennaGuard varistor can be used to protect the FET and offer superior performance to the previously mentioned protection methods given above. The standard EIA 0603 chip size, and particularly the 0402 chip, offer designers an ESD protection solution consistent with today’s downsizing trend in portable electronic products. Savings in component volume up to 86%, and PC board footprint savings up to 83% are realistic expectations. These percentages are based upon the following table and Figures 1A and 1B. mm (inches) Pad Dimensions Suppression Device D1 D2 D3 D4 D5 ® AVX 0402 TransGuard 1.70 (0.067) 0.61 (0.024) 0.51 (0.020) 0.61 (0.024) 0.51 (0.020) AVX 0603 TransGuard® 2.54 (0.100) 0.89 (0.035) 0.76 (0.030) 0.89 (0.035) 0.76 (0.030) Competitor’s SOT23 Diode See Below 0.96 (0.037) D2 0.96 (0.037) D1 D3 2.0 (0.079) D4 0.9 (0.035) D5 Figure 1A. 0402/0603 IR Solder Pad Layout 0.8 (0.031) mm (inch Figure 1B. SOT23- Solder Pad Layout 49 AntennaGuard 0402/0603 AVX Low Capacitance Multilayer Varistors ESD Protection for Antennas and Low Capacitor Loading Applications Antenna varistors offer excellent ESD repetitive strike capability compared to a SOT23 diode when subjected to IEC 61000-4-2 8Kv contact discharge. A performance summary is shown in Figure 2. ANTENNA VARISTOR S21 0 -5 VC04AG183R0 VC06AG183R0 VC06AG18120 70 0603 - 12pF 60 500 480 50 0603 - 3pF 460 40 440 30 420 20 400 10 -10 0402 - 3pF 100 -15 -20 -25 -30 0.01 0.1 1.0 1000 Typical implementations of the antenna varistors are shown for use in cell phone, pager and wireless LAN applications in Figures 6A, 6B and 6C. 8kV ESD Strikes Figure 2. Repetitive 8kV ESD Strike Antenna varistors also turn on and divert ESD overvoltages at a much faster rate than SOT23 devices (typically 300pS vs 1500pS - 5000pS). See Figure 3. FET PEAK 100% 90% 30ns 2.2pF SITVS TURN ON TIME 1.5nS to 5nS 2.7pF Figure 6A. Cell Phone 60ns 1ns MLV TURN ON TIME 300pS to 700pS TIME (ns) 30ns 60ns Figure 3. Turn On Time The equivalent circuit model for a typical antenna varistor is shown in Figure 4. 12pF Ln Ln = BODY INDUCTANCE RV RI C1 C1 = DEVICE CAPACITANCE RV = VOLTAGE VARIABLE RESISTOR Figure 6B. Pager RI = INSULATION RESISTANCE Figure 4. Antenna Varistor The varistor shown exhibits a capacitance of ≤3pF which can be used to replace the parallel capacitance typically found prior to the antenna output of an RF amplifier. In the off state, the varistor acts as a capacitor and helps to filter RF output. The varistor is not affected by RF output power or voltage and has little insertion loss. See Figure 3. 50 10 Frequency (GHz) Figure 5. Antenna vs Frequency 0 10,000 380 0 dB 520 Breakdown Voltage (Vb) — 0603 12pF Rating Breakdown Voltage (Vb) — 0402 & 0603 3pF Ratings ESD TEST OF ANTENNAGUARD RATINGS FET 3pF Varistor Figure 6C.