Sync signal detection apparatus
AssigneeSamsung Electronics Co., Ltd.
InventorShi-hong Park
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Abstract
A device detecting a sync signal is provided, which comprises a sync signal detector having an output selector, an internal clock generator and a combination of three current mirror circuits formed of MOS transistors, and two MOS transistors having resistance characteristics. Irrespective of the high and low state of the input clock signal, the selecting signal for selecting the received sync signal, is made to be high, and the discharge time of the capacitor is minimized so that a capacitor having small capacity can be used and the volume of an integrated circuit element can be minimized and the stable operation is performed, irrespective of the frequency band of the sync signal and the duty thereof.
Claims9
A sync signal detection apparatus comprising:
- output selector means responsive to a control signal for producing an external sync signal as a clock signal, and otherwise producing an internal clock signal as said clock signal;
- an internal clock generator for producing said internal clock signal;
- and,
- sync signal detection means including a first constant-current circuit for generating a first current signal in response to a low amplitude half-cycle of said external sync signal, a second constant-current circuit for generating a second current signal in response to a high amplitude half-cycle of said external sync signal, and a charge/discharge circuit for charging and producing said control signal in response to said first and second current signals, and discharging in response to absence of said external sync signal.
Dependencies are inferred from the claim text.