Dual-Capacitor Pulse Generator for Stable Clock Period Accuracy
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Solution Overview
Problem
Existing pulse generator technologies face accuracy issues in maintaining a consistent period of the output signal due to changes in the ON resistance of switches, which can be affected by the usage environment, leading to errors in the pulse signal period.
Innovation Solution
A pulse generator design that utilizes two periodic voltage generating circuits and comparators to generate pulse signals, where the period is determined by the length of monotonically changing time-periods, independent of the initialization time, ensuring that changes in the usage environment do not affect the pulse signal period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitor charging-discharging circuit is used to generate periodic signals, then the circuit structure is simple, but the output signal period accuracy deteriorates due to switch ON resistance changes
Solution Approach 1:
The patent divides the single capacitor charging-discharging circuit into two separate capacitors (first capacitor and second capacitor) with their own charging and discharging circuits. This segmentation allows independent control of charging and discharging processes, eliminating the interference of switch ON resistance changes on the output signal period accuracy.
2Duration of action of stationary object
If the output signal period is determined by the complete charging-discharging cycle, then the signal generation is continuous, but the period accuracy deteriorates due to environmental changes affecting switch resistance
Solution Approach 1:
The patent extracts the period determination from the complete charging-discharging cycle and bases it solely on the charging time period. By using the charging completion signal (when the first capacitor reaches reference potential) to trigger the output signal edge and initiate the next cycle, the discharging time variations due to switch resistance changes are excluded from the period calculation.
3Ease of operation
If a discharge switch is used to reset the capacitor voltage, then the circuit operation is simplified, but the period accuracy deteriorates because discharge time varies with switch ON resistance
Solution Approach 1:
The patent dynamically switches the roles of the first and second capacitors in each half-cycle. During the first half-cycle, the first capacitor charges and determines the period, while the second capacitor discharges. During the second half-cycle, their roles reverse. This dynamic role switching ensures that the period-determining capacitor is always in the charging phase, where accuracy is maintained.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of the pulse signal period, preventing errors caused by environmental changes and allowing for higher performance in electronic devices using the pulse generator as a clock.
Implementation Method 1
a first periodic voltage generating circuit which charges and discharges a first capacitor and generates a first periodic voltage that periodically repeats a first monotonically changing time-period in which a voltage value changes monotonically from a first initial value towards a first main target value
Implementation Method 2
a second periodic voltage generating circuit which charges and discharges a second capacitor and generates a second periodic voltage that periodically repeats a second monotonically changing time-period in which a voltage value changes monotonically from a second initial value towards a second main target value
Implementation Method 3
a first main comparator which compares a voltage value of the first periodic voltage with the first main target value, and generates a first main switching signal that makes a level transition when these values are equal
Implementation Method 4
a second main comparator which compares a voltage value of the second periodic voltage with the second main target value, and generates a second main switching signal that makes a level transition when these values are equal
Data Source
AI summary
At an occasion of a level transition when a second periodic voltage becomes equal to a main reference voltage a first periodic voltage generating circuit starts a first monotonically changing time-period in which a voltage value of a first periodic voltage increases monotonically from 0, which is an initial value, towards a voltage value of the main reference voltage. At an occasion of a level transition of a first main switching signal when the first periodic voltage becomes equal to the main reference voltage, a second periodic voltage generating circuit starts a second monotonically changing time-period in which a voltage value of the second periodic voltage increases monotonically from 0, which is an initial value, towards a voltage value of the main reference voltage.