Patent ID: 7786775
Filing Date: 2010-08-31
Classification: H03H,H03K

Abstract:
1. A delay circuit comprising: a first delay unit including a plurality of first delay elements connected in series, and receiving a first input signal; a second delay unit including a plurality of second delay elements connected in series, a number of elements being determined in accordance with the number of first delay elements included in the first delay unit, and the second delay unit receiving a second input signal identical with the first input signal and outputting an output signal obtained by delaying the second input signal by a desired delay time (Tt); a detection unit that receives a plurality of output signals from the plurality of first delay elements included in the first delay unit occurring after a predetermined reference time (Tr) since a rising edge or a falling edge of the first input signal is fed to the first delay unit and detects the first delay element outputting an inverted output signal, so as to detect the number of first delay elements used in said first delay unit to delay the first input signal by the reference time (Tr); and a selection unit that, of the output signals from the plurality of second delay elements included in the second delay unit, selects, as the output signal of the second delay unit, the output signal from the second delay element located at the end of a group of second delay elements starting at the element at the input, the number of elements in the group being determined in accordance with the number of first delay elements detected by the detection unit, wherein first delay values (Vd1) applied by the first delay elements included in the first delay unit to a signal input to the first delay element, second delay values (Vd2) applied by the corresponding second delay elements included in the second delay unit to a signal input to the second delay element, and the reference time (Tr) are set so that the ratio (Vd2/Vd1) is equivalent to the ratio (Tt/Tr) between said reference time (Tr) set in the first delay unit and the desired delay time (Tt).