Signal processing circuit

Abstract

A signal processing circuit detects the alteration point of the impulse of the input signal, and sets the phase point which has departed for a prescribed phase width relative to the detected alternation point of the impulse of the input signal. Thereby the sampling to the impulse-shaped input signal can be accurately executed.

Description

technical field [0001] The present invention relates to a signal processing circuit for determining sampling timing. Background technique [0002] When sampling a signal that changes periodically, a phase adjustment circuit is used to appropriately set the sampling timing. For example, it is used to set the sampling phase when RGB digital signals obtained from NTSC or PAL television broadcasting are sampled at a predetermined cycle and output. [0003] Figure 7 It is a figure explaining the conventional phase setting method for sampling. The pulse-like input signal SIG that changes periodically is sampled at the rising edge timing of the reference clock CLK whose cycle is half a cycle of the input signal SIG (the timing indicated by a white circle in the figure). At this time, the timing at which the input signal SIG becomes the maximum value and the minimum value in each cycle is a sampling timing, and the phases of the input signal SIG and the reference clock CLK are ma...

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Problems solved by technology

[0005] However, since the overshoot occurs near the rising edge of the input signal SIG, and the undershoot occurs at the falling edge of the input signal SIG, if the phase of the input signal SIG and the reference clock CLK only slightly deviates, then as Figure 9 As shown, the sampling timing becomes the rising edge and falling edge of the input signal SIG, and the sampling value cannot accurately express the amplitude of the pulse signal.

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