Adaptive clock duty cycle controller (DCC) for automotive system-on-a-chip (SOC)
Aspects of the present disclosure relate to an adaptive clock duty cycle controller (DCC) in an automotive system-on-a-chip (SoC). The adaptive clock DCC may include one or more devices, which may be configured to measure and adapt a duty cycle of a clock signal to compensate for aging effects on components in a signal path of a clock distribution network.
1 . An apparatus, comprising:
a plurality of duty cycle adjusters (DCAs) comprising at least a first DCA and a second DCA, wherein each DCA of the plurality of DCAs is configured to adjust a duty cycle of a clock signal and output the clock signal with an adjusted duty cycle; and
a duty cycle monitor (DCM) coupled to the plurality of DCAs, wherein the DCM is configured to measure duty cycle distortion (DCD) of the duty cycle of the clock signal and duty cycle adjustments performed by the plurality of DCAs, and wherein the first DCA is configured to induce the DCD of the clock signal, the second DCA is configured to correct the duty cycle of the clock signal, and the DCM is configured to measure the duty cycle of the clock signal before and after correction by the second DCA.
2 . The apparatus of claim 1 , wherein:
the first DCA is configured to perform distortion of the duty cycle of the clock signal and output the clock signal with a distorted duty cycle;
the DCM coupled to the first DCA, wherein the DCM is configured to determine the DCD based on measuring one or more parameters of the distorted duty cycle of the clock signal and output DCD measurements of the distorted duty cycle of the clock signal;
a DCA adaptive controller coupled to the first DCA and the DCM, wherein the DCA adaptive controller is configured to determine a duty cycle correction value based on the DCD measurements of the distorted duty cycle of the clock signal received from the DCM and output the duty cycle correction value; and
the second DCA coupled to the first DCA, the DCM and the DCA adaptive controller, wherein the second DCA is configured to adjust the distorted duty cycle of the clock signal to a corrected duty cycle of the clock signal based on the duty cycle correction value received from the DCA adaptive controller.
3 . The apparatus of claim 2 , wherein the DCM is coupled to the first DCA through a clock path between the first DCA and the DCM.
4 . The apparatus of claim 3 , wherein the second DCA is either before the first DCA or after the first DCA in the clock path.
5 . The apparatus of claim 2 , wherein the DCM is configured to measure the corrected duty cycle of the clock signal and determine that the corrected duty cycle of the clock signal is same as an expected duty cycle of the clock signal.
6 . The apparatus of claim 2 , wherein the one or more parameters comprise at least one of a high phase of the clock signal, a low phase of the clock signal, or a period of the clock signal.
7 . The apparatus of claim 2 , wherein at least one of the first DCA, the second DCA, the DCM or the DCA adaptive controller is implemented with a hamming code-based finite state machine (FSM) state encoding.
8 . The apparatus of claim 2 , wherein one or more configuration registers of at least one of the first DCA, the second DCA, the DCM or the DCA adaptive controller are implemented with two dimensional (2D) parity protection codes.
9 . The apparatus of claim 2 , wherein:
one or more configuration registers of at least one of the first DCA, the second DCA, or the DCM comprise a random hardware fault;
the DCD measurements of the distorted duty cycle of the clock signal measured and outputted by the DCM to the DCA adaptive controller are incorrect due to the random hardware fault in the one or more configuration registers of at least one of the first DCA, the second DCA, or the DCM; and
the DCA adaptive controller is configured to detect stuck-at faults at the DCM based on processing of incorrect DCD measurements of the distorted duty cycle of the clock signal during a self-checking test at the apparatus.
10 . The apparatus of claim 2 , wherein the DCM is configured to:
measure the distorted duty cycle of the clock signal before adjustment at the second DCA;
measure the corrected duty cycle of the clock signal after the adjustment at the second DCA; and
verifying that the distorted duty cycle of the clock signal has been corrected based on determining differences between measurements of the distorted duty cycle and measurements of the corrected duty cycle.
11 . The apparatus of claim 2 , wherein a clock for several cycles of the clock signal is gated.
12 . The apparatus of claim 11 , wherein the DCM is configured to:
measure the distorted duty cycle of the clock signal before adjustment at the second DCA;
measure the corrected duty cycle of the clock signal after the adjustment at the second DCA; and
verify that the distorted duty cycle of the clock signal has been corrected and the clock has been ungated, based on determining differences between measurements of the distorted duty cycle and measurements of the corrected duty cycle.
13 . The apparatus of claim 11 , wherein a clock cycle monitoring circuit is coupled to the apparatus, and wherein the clock cycle monitoring circuit is configured to detect a gated clock during a self-checking test at the apparatus.
14 . The apparatus of claim 1 , wherein at least one of the plurality of DCAs is configured to limit an adjustment of the duty cycle of the clock signal based on a threshold duty cycle correction value.
15 . The apparatus of claim 1 , wherein:
one or more configuration registers of at least one of the first DCA, the second DCA, or the DCM comprise a random hardware fault; and
a clock cycle monitoring circuit is coupled to the apparatus, wherein the clock cycle monitoring circuit is configured to detect an incorrect operation at the apparatus due to the random hardware fault during a self-checking test at the apparatus.
16 . A method for a self-checking test, comprising:
adjusting, by each of a plurality of duty cycle adjusters (DCAs) comprising at least a first DCA and a second DCA, a duty cycle of a clock signal and output the clock signal with an adjusted duty cycle; and
measuring, by a duty cycle monitor (DCM) coupled to the plurality of DCAs, duty cycle distortion (DCD) of the duty cycle of the clock signal and duty cycle adjustments performed by the plurality of DCAs, wherein the first DCA induces the DCD of the clock signal, the second DCA corrects the duty cycle of the clock signal, and the DCM measures the duty cycle of the clock signal before and after correction by the second DCA.
17 . The method of claim 16 , further comprising:
performing, by the first DCA, distortion of the duty cycle of the clock signal and outputting the clock signal with a distorted duty cycle;
determining, by the DCM, the DCD based on measuring of one or more parameters of the distorted duty cycle of the clock signal and outputting DCD measurements of the distorted duty cycle of the clock signal;
determining, by a DCA adaptive controller, a duty cycle correction value based on the DCD measurements of the distorted duty cycle of the clock signal received from the DCM and outputting the duty cycle correction value; and
adjusting, by the second DCA, the distorted duty cycle of the clock signal to a corrected duty cycle of the clock signal based on the duty cycle correction value received from the DCA adaptive controller.
18 . The method of claim 17 , further comprising:
measuring, by the DCM, the corrected duty cycle of the clock signal; and
determining, by the DCM, that the corrected duty cycle of the clock signal is same as an expected duty cycle of the clock signal.
19 . The method of claim 17 , wherein the one or more parameters comprise at least one of a high phase of the clock signal, a low phase of the clock signal, or a period of the clock signal.
20 . An apparatus for a self-checking test, comprising:
means for adjusting a duty cycle of a clock signal and output the clock signal with an adjusted duty cycle; and
means for measuring duty cycle distortion (DCD) of the duty cycle of the clock signal and duty cycle adjustments performed by a plurality of duty cycle adjusters (DCAs), wherein the DCD of the clock signal is induced, the duty cycle of the clock signal is corrected, and the duty cycle of the clock signal is measured before and after the correction.