Semiconductor device, radio communication terminal using same, and clock frequency control method
First Claim
1. A semiconductor device comprising:
- a clock generation circuit that changes a frequency of an output clock signal according to a control signal;
an arithmetic circuit that operates according to the clock signal;
a storage circuit that is activated according to access from the arithmetic circuit;
a memory access detection unit that detects a number of accesses from the arithmetic circuit to the storage circuit, and when the number of accesses increases, outputs a request signal to lower the frequency of the clock signal; and
a clock control circuit that generates the control signal for lowering the frequency of the clock signal according to the request signal,wherein the memory access detection unit comprises a second comparator that compares a variation of an index number calculated from the number of accesses with a second reference value, and when the variation of the index number exceeds the second reference value, outputs a second request signal as the request signal.
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Accused Products
Abstract
A semiconductor device 1 includes a clock generation circuit 15 that changes a frequency of an output clock signal according to a control signal div, an arithmetic circuit (e.g., CPU0) that operates according to the clock signal, a storage circuit (e.g., IC0) that is activated according to access from the arithmetic circuit CPU0, a memory access detection unit 12 that detects a number of accesses from the arithmetic circuit CPU0 to the storage circuit IC0, and when the number of accesses increases, outputs a request signal (e.g., psreq1), and a clock control circuit 14 that generates the control signal div for lowering the frequency of the clock signal according to the request signal psreq1.
16 Citations
21 Claims
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1. A semiconductor device comprising:
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a clock generation circuit that changes a frequency of an output clock signal according to a control signal; an arithmetic circuit that operates according to the clock signal; a storage circuit that is activated according to access from the arithmetic circuit; a memory access detection unit that detects a number of accesses from the arithmetic circuit to the storage circuit, and when the number of accesses increases, outputs a request signal to lower the frequency of the clock signal; and a clock control circuit that generates the control signal for lowering the frequency of the clock signal according to the request signal, wherein the memory access detection unit comprises a second comparator that compares a variation of an index number calculated from the number of accesses with a second reference value, and when the variation of the index number exceeds the second reference value, outputs a second request signal as the request signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A semiconductor device, comprising:
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a clock generation circuit that changes a frequency of an output clock signal according to a control signal; an arithmetic circuit that operates according to the clock signal; a storage circuit that is activated according to access from the arithmetic circuit; a memory access detection unit that detects a number of accesses from the arithmetic circuit to the storage circuit, and when the number of accesses increases, outputs a request signal to lower the frequency of the clock signal; and a clock control circuit that generates the control signal for lowering the frequency of the clock signal according to the request signal, wherein the memory access detection unit comprises; a first comparator that compares an index number calculated from the number of accesses with a first reference value, and when the index number exceeds the first reference value, outputs a first request signal as the request signal; and a second comparator that compares a variation of the index number with a second reference value, and when the variation of the index number exceeds the second reference value, outputs a second request signal as the request signal, and wherein the clock control circuit comprises; a first clock adjustment unit that generates a first control signal as the control signal according to the first request signal, the first control signal being used to decrease a number of clocks output in a predetermined period in a stepwise manner; and a second clock adjustment unit that generates a second control signal as the control signal according to the second request signal, the second control signal being used to decrease the number of clocks output in the predetermined period to a lower limit value. - View Dependent Claims (14)
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15. A clock frequency control method for a clock signal supplied to a semiconductor device comprising an arithmetic circuit that operates according to the clock signal and a storage circuit that is activated according to access from the arithmetic circuit, the clock frequency control method comprising:
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detecting a number of accesses from the arithmetic circuit to the storage circuit; calculating an index number based on the number of accesses; comparing a variation of the index number with a first reference value; and lowering a frequency of the clock signal when the variation of the index number exceeds the first reference value due to an increase in the number of accesses. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification