® )LOWHULQJDW&RQQHFWRUV Note: Metalized Plastic connected to X2Y-grounds Change Tltle Delivery of Clean Signals 2 Best EMI filtering achievable. New standards on emission (radiation ) can be met. Two data lines can be filtered simultaneously with one X2Y filter. Improved ESD performance. Change Tltle Benefits of filtering with X2Y balanced filters in Connectors 3 G1 A B G2 4 Change Tltle X2Y Capacitor Construction X2Y Technology takes the standard multi-layer capacitor technology and inserts ground electrodes between each two “hot” electrodes. The new ground electrode plates are then commonly connected to the sides of the component forming a four terminal device. X2Y Cap Four Terminal X2Y Change Tltle Standard Cap 5 X2Y: Three Devices In One The new component becomes a dual line element when attached between oppositely phased or charged conductors and a ground. Three separate devices, 1 X cap and 2 balanced Y caps, are now integrated into one package, reducing component count, placement costs and board space. The X2Y-device filters in both common mode and differential mode, simultaneously. - - 2 Y caps line to ground A Single X2Y Capacitor 1 X cap line to line + 2 Y caps line to ground 1 X cap line to line + Change Tltle Three Standard Capacitors 6 &RPPRQ0RGH Common Mode Noise with Regular Capacitors Two regular capacitors must be sorted for equal capacitance tolerance when manufactured (an extra cost). Two regular capacitors are mounted on the same side of a common ground, the inductance is in series and ground potential of each line can vary widely. B I com noise A I com noise Change Tltle Parasitic Capacitance 7 'LIIHUHQWLDO0RGH Differential Mode Noise with Regular Capacitors B I diff noise A I diff noise Change Tltle When a regular capacitor capacitor is used between lines A and B, filtering of differential mode noise is only effective in a narrow band around the resonant frequency. Additional capacitors of varying capacitance must be added to broaden effective low impedance range. 8 ,PSHGDQFH Insertion Loss curves (common mode) of standard MLCCs and unbalanced MLCCs versus a X2Y capacitor. Unbalanced Regular Caps dB Regular Caps Effective range. MHz GHz Change Tltle X2Y 9 Standard Caps, Series Impedance When two regular capacitors are placed in parallel, the capacitance adds and the impedance of the PCB board ground between the two capacitors is in series which has an effect on their self-resonant frequency, and hence on the effective frequency range. Standard caps have in series ground connection C1 TRACE PCB Board Ground Change Tltle TRACE C2 10 X2Y Caps, Parallel Impedance In the X2Y architecture, the internal ground plates are connected in parallel to reduce the internal selfimpedance before the device is connected to the PCB board ground. Once attached, the selfimpedance of X2Y is in parallel with the PC board ground impedance. Therefore, the total impedance of the X2Y and the PC board ground is reduced, increasing the effective frequency range of the device. X2Y caps are in parallel 1/Z t = 1/Z 1 + 1/Z 2 …. C1 PCB Board Ground Change Tltle C2 11 ,PSHGDQFH Impedance curve of a parallel circuit of two standard MLCCs versus one X2Y circuit A X2Y device has extreme low Inductance. The ground plane is inside the X2Y device. The distance between electrode and ground is just a dielectric thickness !! C1 C2 Regular Caps Effective range Zo PCB Board Ground GHz MHz C1 X2Y-cap Improved effective range Zo MHz GHz C2 PCB Board Ground Change Tltle X2Y Ground Layer 12 X2Y, Low Inductance E and H-field cancellation within X2Y yields extremely low self-inductance. PicoHenry inductance levels and parallel connection to the PC Board, make X2Y the next generation replacement for low inductance reverse aspect-ratio capacitors. nH Radial Leaded Inductance MLCC Smaller MLCC pH X2Y 1980’s 1990’s Time Original Chart Source: AVX CORP 2000’s Change Tltle Reverse Aspect Ratio 13 Standard Caps Radiate Change Tltle Standard components do not have the X2Y Faraday cage and radiate at high frequency. Their magnetic flux can couple to nearby traces, introducing unwanted peaks or traps in filtering characteristic. Side mounting of standard caps is sometimes used to reduce this problem (minimum coupling under right angles). 14 Faraday Cage inside X2Y-component. The newly added shield/ground-electrodes and the side terminations form a Faraday cage, surrounding the “hot” electrodes. E-field and H-field parasitics are contained within the component. X2Y uses capacitive coupling to charge the internal ground electrodes of the component with opposite +/charges which cancel the E-field. The H-field of the opposing currents are 180 degrees out of phase and cancel within the component shield-electrodes. _ + A A _ _ _ _ _ _ + + _ + _ _ + + + + + + + B Cross section A Cross section B _ Change Tltle B 15 X2Y has demonstrated fast response to transients not normally expected with capacitors. The low self-inductance of X2Y combined with its low impedance connection allows the capacitance to clip the transient. Standard components have too much series inductance and so varistor material must be used to shunt energy to ground. X2Y surge time < 500 psec. A 200nF discoidal X2Y has survived +/-25kV surge pulse (EMP) @ 150 and 300 Ohms in military testing. Change Tltle Transient Suppression 16 Two balanced Y capacitors with a very tight capacitance tolerance. Equal aging and temperature tracking on each Y capacitor helps to maintain balance. Capacitance variation vs. voltage is equalized line-to-line, especially beneficial when using dielectrics such as Y5V. Reliability goes up when using a single X2Y component vs. three standard caps. Change Tltle Other X2Y Benefits 17