Patent ID: 8311173
Filing Date: 2012-11-13
Classification: H04L

Abstract:
1. A frame pulse signal latch circuit comprising: a racing detection unit which detects a racing state generated due to phase relation between a frame pulse signal and a first clock signal for latching the frame pulse signal; a phase control unit which determines a phase adjustment amount for adjusting a phase of the first clock signal based on the phase and cycle of the first clock signal when the racing state is detected by the racing detection unit; a phase adjustment unit which generates the first clock signal by adjusting a phase of an input second clock signal in accordance with the phase adjustment amount determined by the phase control unit; and a latch unit which latches the frame pulse signal based on the first clock signal generated by the phase adjustment unit and generates an output frame pulse signal, wherein the racing detection unit comprises: a pulse generation unit, which generates a first pulse signal, which becomes a high level in a period in which the output frame pulse signal can become the high level when the racing state is generated, and a second pulse signal, which has a phase different from a phase of the first pulse signal by the period corresponding to one cycle of the first clock signal; a first counter, which counts the number of times that the output frame pulse signal becomes the high level when the first pulse signal is at the high level; a second counter, which counts the number of times that the output frame pulse signal becomes the high level when the second pulse signal is at the high level; and a determination unit, which determines that the racing state is generated when count values of both the first counter and the second counter are equal to or more than a predetermined value.