Ripple Counter Frequency Divider With Masked Reload Glitch Suppression
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Solution Overview
Problem
As the number of counters in a ripple counter increases, the delays in frequency dividers used in wireless communication systems become more significant, affecting the performance of multi-modulus frequency divider circuits.
Innovation Solution
A frequency divider circuit comprising a ripple counter unit, a reload signal output unit, and a state extend unit, where the reload signal output unit determines the termination state of the ripple counter and outputs a reload signal, and the state extend unit generates a mask signal to address the delays by masking unknown outputs, thereby improving the accuracy of frequency division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of counters in the ripple counter is increased to achieve higher frequency division ratios, then the frequency division accuracy is improved, but the delay time increases significantly
Solution Approach 1:
The mask signal is generated in advance based on the reload signal before the frequency divided signals are fully stable. The state extend unit extends the valid time window of the mask signal to cover the period when frequency divided signals may still be transitioning, ensuring that glitch signals are masked before they can affect the frequency division accuracy.
Solution Approach 2:
The mask signal acts as an intermediary between the reload signal and the frequency divided signals. It mediates the interaction by selectively enabling or disabling the passage of frequency divided signals based on their stability, thus preventing unstable signals from affecting the output while allowing stable signals to pass through.
2Adaptability or versatility
If the number of counters in the ripple counter is increased to achieve multi-modulus frequency division, then the versatility is improved, but the reliability decreases due to more glitches
Solution Approach 1:
The mask signal serves as an intermediary that filters out unreliable frequency divided signals. It is generated based on the reload signal and extends to cover the period when frequency divided signals are unstable, thereby blocking glitch signals from propagating to the output while allowing stable signals to pass through, thus maintaining reliability in multi-modulus frequency division operations.
Solution Approach 2:
The reload signal output unit detects the termination state of the ripple counter and generates the mask signal accordingly. This feedback mechanism ensures that the mask signal is dynamically adjusted based on the actual state of the counter, providing reliable glitch suppression adaptively for different modulus values.
3Device complexity
If the ripple counter is used for frequency division, then the device complexity is reduced, but the measurement precision deteriorates due to delay accumulation
Solution Approach 1:
The mask signal acts as an intermediary that compensates for the precision loss caused by delay accumulation in the ripple counter. By extending the mask signal duration to cover the period when frequency divided signals are still transitioning, it ensures that only stable and accurate signals are passed to the output, thereby maintaining frequency division accuracy despite the simple ripple counter structure.
Solution Approach 2:
The mask signal is generated in advance based on the reload signal, before the frequency divided signals complete their transitions. This preliminary action ensures that the output is protected from inaccurate signals during the transition period, maintaining measurement precision without requiring a more complex counter structure.
Data Source
AI summary
An embodiment of the present invention discloses a frequency divider. The frequency divider comprises a ripple counter unit, a reload signal output unit and a state extend unit. The ripple counter unit is configured to output a plurality of frequency divided signals according to a clock signal. The reload signal is output unit, coupled to the ripple counter unit, and is configured to determine whether the ripple counter unit is in a termination state and output a reload signal according to the frequency divided signals and a mask signal. The state extend unit is coupled to the ripple counter unit and the reload signal output unit, and is configured to output the mask signal according to the reload signal.