Samsung Electronics Co., Ltd.

Joung-ho Kim

Jong-hoon Kim

Jung-gun Byun

Pil-jung Jun

Dong-gun Kam

A spread spectrum clock generator includes a plurality of delay cells, wherein each delay cell includes at least one delayer receiving an external clock signal and causing a predetermined propagation delay to the received clock signal, and a controller transmitting a control signal to the delayer to control the propagation delay of the delayer according to a state value of the control signal. With this configuration, the spread spectrum clock generator using a delayer can have a simple circuit configuration and effectively attenuate an EMI.

Spread spectrum clock generator

A frequency doubler circuit implemented in an integrated circuit and having improved doubling performance is provided. The frequency doubler circuit including a phase shifter, a first buffer, a second buffer, a detect-control unit, a third buffer, a fourth buffer, a multiplier and an output buffer. The phase shifter outputs, in response to an input signal having a predetermined frequency, a first signal which is in phase with the input signal and a second signal which is out-of-phase from the input signal. The first buffer filters and buffers the first signal, and the second buffer filters and buffers the second signal. The detect-control unit detects a phase difference between the first and second signals in response to the first signal, the second signal, the output signal of the first buffer and the output signal of the second buffer, and outputs first and second control signals. The third buffer buffers the output signal of the first buffer in response to the first control signal, and the fourth buffer buffers the output signal of the second buffer in response to the second control signal. The multiplier multiplies the output signals of the third and fourth buffers. The second signal differs from the first signal by about 90&deg;.

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Kyungki-do, South Korea

Joung-ho Kim