Any long signal path on the printed circuit board of an on-line splitter can be regarded as a transmission line. If the delay time transmitted by the line is a much shorter rise time signal, the rise of the signal reflects that the Lord will be swallowed. No longer will overshoot, recoil and ring. Most existing MOS circuits can grow in meters without signal distortion because the rise time line transmission delay time ratio is greater. Faster logic circuits, especially high-speed emitter coupled logic.
Due to the high speed of the integrated circuit of the on-line board splitter and the margin of no other measures, it is necessary to shorten the tracking length in order to adhere to the signal integrity.
There are two ways for the on-line board splitter to make the high-speed circuit work in a relatively long line without severe waveform distortion. The TTL falling edge fast Schottky diode clamp method is to clamp more than one diode below the ground potential level, so as to reduce the rear recoil of the amplitude and slow down the attenuation of the rising edge. However, the circuit under the h-level condition has relatively high output impedance. In addition, since the level H national exemption is large, the problem is not very prominent. For the recoil HCT series equipment, the improvement effect will be more significant by using a Schottky diode clamp and series resistor termination method.
When a fan's signal line, the online board splitter has a higher bit rate and speed advantage, the method described above is often not TTL characterization. Because there is a reflected wave line, they tend to be composed at high rate, resulting in severe signal distortion and interference reduction. Therefore, in order to deal with the reflection problem, the emitter coupling logic system is another method commonly used: line impedance matching method. In this way, the control can reflect and ensure the signal integrity.
Strictly speaking, the on-line board splitter has a slower speed. For traditional TTL marginal and CMOS devices, transmission lines are not necessary. With a faster marginal speed, high-speed emitter coupled logic devices, transmission lines are not always needed. However, when using transmission lines, it is necessary to predict the advantages and oscillations reflected by connection delay and manipulation impedance.