0783730001_Molex_Memory Connectors - Inline Module Sockets

ESD protection's effect Placing ESD protection on HDMI signals affects edge rates of high-speed signals and trace impedances localized to the area of the ESD protection for single-ended and differential signals.

The placement of ESD diodes also affects the performance of high-speed signals. Placing ESD components on high-speed signals is similar to placing small capacitors on the signal lines and introducing parasitic capacitance. In order to minimize their impact on high-speed signals, ESD components for HDMI will have parasitic capacitance below 1pF.

0783730001_Molex_Memory Connectors - Inline Module Sockets

High-speed signals The overall effect on the HDMI signal will be a decrease in the slew rate of the signal, introducing additional jitter and lowering the bandwidth for the signal.

The impact of adding an ESD protection diode to a high-speed signal is shown in Figure 2 .

0783730001_Molex_Memory Connectors - Inline Module Sockets

Figure 2: TMDS edge rate with ESD diode

The transition rate requires 150ps, compared to the waveform in Figure 4 that transitions in 100ps without ESD diodes. In addition, the ESD diode will result in additional jitter as shown by the varied signal crossing.

0783730001_Molex_Memory Connectors - Inline Module Sockets

Figure 3: TMDS edge rate with ESD diode simulation circuit

The second distortion mechanism is that the strength of the magnet's field is not actually constant in operation but is changed by the current from the amplifier through the coil. This change occurs because the amplifier current through the coil generates the force to move the diaphragm by creating its own magnetic field that pushes” against the magnet's field.

The magnet is somewhat demagnetized by the coil's magnetic field when current flows in one direction and is remagnetized when current flows in the opposite direction. Therefore, since the magnet's field strength is not constant, the force generated is not in the desired direct proportion to the current in the coil.

To greatly reduce this effect the SS2 drivers incorporate a thick copper ring around the center pole. With this ring any changes in the magnet's strength induces an electrical current in the ring which generates a magnetic field that is opposed to and practically cancels the original change.

Copper pole sleeve and ring used in the SS2 woofers to stabilize the magnetic field strength for reduced distortion.

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