Clock management apparatus, clock frequency division module and system-on-chip

Patent metadata

Field	Value
Publication number	US-12375087-B2
Application number	US-202118548044-A
Country	US
Kind code	B2
Filing date	Dec 31, 2021
Priority date	Feb 25, 2021
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

Provided is a clock management apparatus wherein the clock management apparatus includes a clock synchronization signal generator, a plurality of clock gating units and clock frequency division modules; a synchronization signal of a predetermined period is generated by the clock synchronization signal generator; each of the clock gating units is connected in series with a corresponding one of the clock frequency division modules to form a signal processing branch; and the signal processing branches are connected in parallel to receive a source clock signal respectively, the clock gating unit controls the on-off switch of the signal processing branch, and the clock frequency division modules are configured to perform phase adjustment on the clock signals of the signal processing branches after receiving the synchronization signal output by the clock synchronization signal generator, and to adjust the clock signals of the signal processing branches from an asynchronous state to a synchronous state.

First claim

The invention claimed is:

1. A clock management apparatus, comprising a clock synchronization signal generator, a plurality of clock gating units, and a plurality of clock frequency division modules;
wherein the clock synchronization signal generator is configured to generate a synchronization signal of a predetermined period;
the plurality of clock gating units are in one-to-one correspondence with the plurality of clock frequency division modules, and each of the plurality of clock gating units is connected in series with a corresponding one of the plurality of clock frequency division modules to form a signal processing branch; a plurality of the signal processing branches are connected in parallel and configured to receive a source clock signal respectively; the clock gating unit is configured to control an on-off switch of the signal processing branch, and the clock frequency division module is configured to perform phase adjustment on a clock signal of the signal processing branch after receiving a synchronization signal output by the clock synchronization signal generator, to adjust clock signals of the plurality of signal processing branches from an asynchronous state to a synchronous state.

2. The clock management apparatus according to claim 1 , wherein clock signals output by the plurality of signal processing branches are used as operating clocks of a plurality of clock domains respectively.

3. The clock management apparatus according to claim 2 , wherein the predetermined period is a common multiple of periods of the operating clocks of the plurality of clock domains.

4. The clock management apparatus according to claim 1 , wherein the clock frequency division module comprises a state machine, a synchronization signal delay circuit, and a clock generation circuit;
wherein the synchronization signal delay circuit is configured to delay a synchronization signal after receiving the synchronization signal output by the clock synchronization signal generator;
the state machine is configured to control the clock generation circuit to, after receiving the delayed synchronization signal, adjust the phase of the output clock in response to the clock signals of the plurality of current signal processing branches being in the asynchronous state.

5. The clock management apparatus according to claim 4 , wherein the clock frequency division module further comprises a counter and a comparator;
wherein the counter is configured to perform periodic counting under control of the state machine to determine a current count value;
the comparator is configured to compare the current count value with a maximum count threshold of the clock frequency division module, and output state information about whether the current state is a synchronous state; wherein the comparator is configured to output the state information that the current state is the synchronous state in response to the current count value being consistent with the maximum count threshold, and output the state information that the current state is the asynchronous state in response to the current count value being inconsistent with the maximum count threshold;
the state machine is configured to receive the state information sent by the comparator;
wherein the maximum count threshold is a value obtained by subtracting 1 from a preset frequency division ratio of the clock frequency division module.

6. The clock management apparatus according to claim 5 , wherein the clock frequency division module further comprises a frequency division ratio register configured to store the maximum count threshold.

7. The clock management apparatus according to claim 6 , wherein when a value of the preset frequency division ratio is adjusted, a value of the maximum count threshold stored in the frequency division ratio register is modified in response to the clock signal being in the synchronous state and the clock frequency division module receiving the synchronization signal.

8. The clock management apparatus according to claim 5 , wherein the state machine is configured to switch to the asynchronous state after receiving the state information that the current state is the asynchronous state, and control the clock generation circuit to turn off the clock output;
after the counter counts to the maximum count threshold, the state machine is configured to switch to a phase adjustment state, and the counter records a current count value as a phase offset value when a synchronization signal occurs; and when the counter continues to count to the phase offset value, the state machine is configured to control the clock generation circuit to turn on the clock output.

9. The clock management apparatus according to claim 8 , wherein the clock generation circuit is implemented by using a clock gating unit or a flip-flop.

10. The clock management apparatus according to claim 4 , wherein the state machine is configured to switch to the asynchronous state in response to a signal corresponding to the clock gating unit being enabled or reset.

11. The clock management apparatus according to claim 4 , wherein the synchronization signal delay circuit is configured to, after receiving the synchronization signal output by the synchronization signal generator, delay the synchronization signal by a multiple of a period of the source clock according to a preset frequency division clock phase offset value.

12. A clock frequency division module, comprising a state machine, a synchronization signal delay circuit, and a clock generation circuit;
wherein the synchronization signal delay circuit is configured to delay a synchronization signal after receiving the synchronization signal;
the state machine is configured to, after receiving the delayed synchronization signal, control the clock generation circuit to adjust a phase of the output clock in response to a current clock signal and other clock signals being in an asynchronous state;
wherein the clock frequency division module further comprises a counter and a comparator;
wherein the counter is configured to perform periodic counting under control of the state machine to determine a current count value;
the comparator is configured to compare the current count value with a maximum count threshold of the clock frequency division module, and output state information about whether a current state is a synchronous state; the comparator is configured to output the state information that the current state is a synchronous state in response to the current count value being consistent with the maximum count threshold, and output the state information that the current state is an asynchronous state in response to the current count value being inconsistent with the maximum count threshold;
the state machine is configured to receive the state information sent by the comparator;
wherein the maximum count threshold is a value obtained by subtracting 1 from a preset frequency division ratio of the clock frequency division module.

13. A system-on-chip, comprising a clock management apparatus, wherein the clock management apparatus is configured to output clock signals for use in the same or different functional modules of the system-on-chip;
the clock management apparatus comprising a clock synchronization signal generator, a plurality of clock gating units, and a plurality of clock frequency division modules;
wherein the clock synchronization signal generator is configured to generate a synchronization signal of a predetermined period;
the plurality of clock gating units are in one-to-one correspondence with the plurality of clock frequency division modules, and each of the plurality of clock gating uni

Assignees

• Espressif Sys Shanghai Co Ltd

Inventors

• He Yaqian
• Tong Li

Classifications

• H03K5/22

  Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral (indicating phase difference of two cyclic pulse trains G01R25/00) · CPC title

• H03K3/037

  Bistable circuits · CPC title

• G06F1/12

  Synchronisation of different clock signals {provided by a plurality of clock generators} · CPC title

• G06F1/08

  Clock generators with changeable or programmable clock frequency · CPC title

• H03K21/406

  Synchronisation of counters · CPC title