Via Technologies, Inc.

Hui-Mei Chen

Hung-Yi Kuo

Weber Chuang

A switching circuit located in a computer system is disclosed in the present invention. The switching circuit comprises a first phase-locked loop generating a first host clock signal, a second phase-locked loop generating a second host clock signal and an output switch unit coupled to the first PLL and the second PLL. When the computer system operates in a first mode, the output switch unit chooses the first host clock signal to be a fundamental clock signal of the front side bus. In the other hand, when the computer system operates in a second mode, the output switch unit chooses the second host clock signal to be a fundamental clock signal of the front side bus.

Switching circuit and method thereof for dynamically switching host clock signals

By adjusting a scale factor of a phase locked loop in computers for generating a basic clock signal of a front-side bus, the frequency of the basic clock signal is modulated when the central processing unit of computers operates. By a bridge unit of the present invention, a selecting signal is received so as to output a corresponding adjustment signal to a check unit and then the check unit checks the adjustment signal for outputting a checking signal to a scale parameter adjustment unit. According to the checking signal, the scale parameter adjustment unit adjusts a first scale parameter of the scale factor that the phase locked loop uses now and outputs this parameter to the phase locked loop. Thus after receiving a fixed clock signal for generating the basic clock signal, the phase locked loop generates the basic clock signal of the front-side bus in accordance with the adjusted first scale parameter and further the frequency of the basic clock signal is adjusted.

Dynamic adjusting circuit for basic clock signal of front-side bus and method thereof

A timing adjustment circuit and method thereof are disclosed. The timing adjustment circuit at least consists of a second timing adjustment unit, a multistage sample circuit, and a decision circuit for adjusting received timing of an output signal transmitted by a first chip and received by a second chip. The method takes advantage of the multistage sample circuit to receive a clock signal of receiving end so as to generate a plurality of sample clock signal. Later, according to the sample clock signals, sample output signals to generate a plurality of sampled signal. At last, make comparison of the sampled signals by the decision circuit in accordance with the output signals to generate a second adjustment signal being transmitted to the second timing adjustment unit for adjusting phase of a base clock to generate an adjusted receiving-end clock signal. Thus the receiving timing of the second chip to receive the output signal is adjusted. Moreover, the decision circuit sends a first adjustment signal to a first timing adjustment unit of the timing adjustment circuit for generating an adjusted output-end clock signal. Thus the output timing that the first chip transmits the output signal to the second chip is adjusted.

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Hsin-Tien, Taiwan

Hui-Mei Chen