Low Power Clock Gating Circuit
First Claim
1. A circuit comprising:
- an input circuit configured to receive an enable signal;
clock enable circuitry configured to receive a clock signal;
a latch configured to capture and store an enabled state of the enable signal, wherein the enabled state corresponds to the enable signal being in an active state, wherein the latch comprises a feed forward circuit having a feed forward node and a feedback circuit having a feedback node, wherein the feedback circuit is coupled to provide a feedback signal to the feed forward circuit, wherein the feed forward circuit is configured to capture a current state of the enable signal when the clock signal is inactive, and wherein the feedback circuit is configured to cause the feed forward circuit to retain the enabled state of the enable signal when the clock signal transitions from a logic high state to a logic low state;
an output circuit configured to provide an output signal corresponding to a state of the clock signal when the latch is storing the enabled state;
wherein the circuit is configured such that dynamic power consumption does not change responsive to a change in the state of the clock signal when the latch is not storing the enabled state.
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Accused Products
Abstract
A clock gating circuit is disclosed. The clock gating circuit includes an input circuit configured to receive an enable signal and clock enable circuitry configured to receive an input clock signal. The clock gating circuit also includes a latch that captures and stores an enabled state of the enable signal when the enable signal is asserted. An output circuit is coupled to the latch, and provides an output signal corresponding to a state of the clock signal when the latch is storing the enabled state. The clock gating circuit is arranged such that, when the latch is not storing the enabled state, no dynamic power is consumed responsive to state changes of the input clock signal.
25 Citations
20 Claims
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1. A circuit comprising:
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an input circuit configured to receive an enable signal; clock enable circuitry configured to receive a clock signal; a latch configured to capture and store an enabled state of the enable signal, wherein the enabled state corresponds to the enable signal being in an active state, wherein the latch comprises a feed forward circuit having a feed forward node and a feedback circuit having a feedback node, wherein the feedback circuit is coupled to provide a feedback signal to the feed forward circuit, wherein the feed forward circuit is configured to capture a current state of the enable signal when the clock signal is inactive, and wherein the feedback circuit is configured to cause the feed forward circuit to retain the enabled state of the enable signal when the clock signal transitions from a logic high state to a logic low state; an output circuit configured to provide an output signal corresponding to a state of the clock signal when the latch is storing the enabled state; wherein the circuit is configured such that dynamic power consumption does not change responsive to a change in the state of the clock signal when the latch is not storing the enabled state. - View Dependent Claims (2, 3, 5, 7, 8, 9, 10)
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4. (canceled)
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6. (canceled)
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11. A method comprising:
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providing a clock signal to a clock gating circuit, the clock signal having an active state corresponding to a first logic level and an inactive state corresponding to a second logic level; enabling the clock gating circuit responsive to assertion of an enable signal; storing, in a latch, an enabled state of the enable signal, wherein storing the enabled state includes a feed forward circuit capturing the enabled state of the enable signal when the clock signal is inactive and a feedback circuit providing a feedback signal to the feed forward circuit to cause the feed forward circuit to retain the enabled state of the enable signal when the clock signal transitions from the active state to the inactive state; providing an output signal corresponding to a current state of the clock signal when the clock gating circuit is enabled; holding the output signal to a predetermined state, irrespective of a state of the clock signal, when the clock gating circuit is not enabled; and inhibiting dynamic power consumption by the clock gating circuit due to state transitions of the clock signal when the clock gating circuit is not enabled. - View Dependent Claims (12, 14)
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13. (canceled)
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15. A clock gating circuit, comprising:
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an input circuit configured to receive an enable signal; clock enable circuitry configured to receive a clock signal, the clock signal having an active state corresponding to a first logic level and an inactive state corresponding to a second logic level; a latch configured to capture and store, on a storage node, a state of the enable signal, wherein the latch is configured to capture a current state of the enable signal on the storage node when the clock signal is in an inactive state, and further configured to inhibit logical transitions of the storage node when the clock signal is in an active state, wherein the latch includes a feed forward circuit and a feedback circuit, wherein the feedback circuit includes an input coupled to the storage node and is coupled to provide a feedback signal to the feed forward circuit, wherein the feed forward circuit is configured to retain, responsive to the feedback signal, an asserted state of the enable signal on the storage node when the clock signal transitions to the inactive state; and an output circuit configured to provide an output signal corresponding to a current state of the clock signal when the latch is storing the asserted state of the enable signal; wherein the clock enable circuitry is configured to enable transitions of the output signal when the latch is storing the asserted state of the enable signal, and further configured to inhibit dynamic power consumption by the clock gating circuit, irrespective of transition by the clock signal, when the latch is not storing the asserted state of the enable signal. - View Dependent Claims (17, 18, 19, 20)
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16. (canceled)
Specification