Semiconductor integrated circuit
First Claim
1. A semiconductor integrated circuit wherein an analog circuit operating in response to a first clock signal and a digital circuit operating in response to a second clock signal having the same period as that of the first clock signal are formed on the same semiconductor substrate;
- comprising on the semiconductor substrate;
a plurality of phase shift circuits each relatively shifting a phase of one of the first clock signal and the second clock signal from a phase of the other of the first clock signal and the second clock signal by a different value; and
a noise measuring circuit for measuring a noise component generated by the analog circuit.
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Accused Products
Abstract
Even when variation in transistor characteristic, resistance or the like occurs during manufacturing, a noise component is always minimized. Each of k clock phase difference generating circuits 16-18 shifts a phase of a basic clock signal ADCK1 by a specified different value to obtain a clock signal ADCK2 and supplies the clock signal ADCK2 to an A/D converter. A k counter 19 successively selects the clock phase difference generating circuits 16-18 and stores a noise component in an output of the A/D converter measured by a noise measuring circuit 27 in a corresponding register. A comparator 25 compares k noise components and obtains the number j of the clock phase difference generating circuit giving a minimum value. A selection circuit 26 fixedly selects only the j-th clock phase difference generating circuit. Thus, even when variation in the transistor characteristics or resistance occurs in each device in a manufacturing stage, the clock signal ADCK2 obtained by shifting the phase of the basic clock signal ADCK1 can be supplied to the A/D converter so that a noise component is minimized for each device.
12 Citations
6 Claims
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1. A semiconductor integrated circuit wherein an analog circuit operating in response to a first clock signal and a digital circuit operating in response to a second clock signal having the same period as that of the first clock signal are formed on the same semiconductor substrate;
- comprising on the semiconductor substrate;
a plurality of phase shift circuits each relatively shifting a phase of one of the first clock signal and the second clock signal from a phase of the other of the first clock signal and the second clock signal by a different value; and
a noise measuring circuit for measuring a noise component generated by the analog circuit. - View Dependent Claims (2, 3, 4, 5, 6)
- comprising on the semiconductor substrate;
Specification