Pulse Modulation Circuit With Adjustable High-Frequency Limiting
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Solution Overview
Problem
Conventional pulse generating circuits produce excessively high frequencies, which is not suitable for applications with hardware system overhead considerations, as there is no existing circuit to limit the highest frequency effectively.
Innovation Solution
A pulse modulation circuit with a high-frequency-limiting function is designed, incorporating a first and second level output unit, voltage comparators, RS trigger, NAND gate, and NOR gate, along with switching triodes and charging capacitors, where the frequency is controlled by adjusting bias currents and reference voltages, allowing for the limitation of the highest output frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional pulse generating circuit is used, then the circuit is simple in structure, but the output frequency is excessively high which increases hardware system overheads
Solution Approach 1:
The pulse generating circuit is divided into multiple functional modules: a comparator module for generating basic pulse signals, a frequency limiting module with monostable multivibrators for controlling maximum frequency, and an output module. This segmentation allows independent optimization of each module, keeping the overall structure relatively simple while effectively limiting the output frequency through the frequency limiting module's time constant configuration.
Solution Approach 2:
The patent uses parameter changes to limit frequency by configuring the time constants (RC constants) of the monostable multivibrators in the frequency limiting module. By adjusting the resistance and capacitance values, the maximum output frequency is controlled without fundamentally changing the circuit topology, thus maintaining structural simplicity while achieving frequency limitation.
2Loss of energy
If the output frequency is limited to reduce hardware overheads, then hardware system overheads are reduced, but the pulse generating circuit's frequency control capability is insufficient in conventional designs
Solution Approach 1:
The patent incorporates feedback mechanisms where the output of the frequency limiting module feeds back to control the pulse generation process. The monostable multivibrators are triggered by the comparator output and their reset signals feed back to the comparator, creating a controlled loop that limits frequency while maintaining adaptability through adjustable RC time constants.
Solution Approach 2:
The circuit uses dynamic elements (capacitors charging and discharging through resistors) to create time-dependent behavior. The RC time constants provide dynamic control over the pulse width and frequency, allowing the circuit to adapt to different frequency requirements by simply changing component values rather than redesigning the entire circuit.
Data Source
AI summary
A pulse modulation circuit with a high-frequency-limiting function, including a comparator, an RS trigger, a switching triode, a NAND gate, a NOR gate, and a charging capacitor. A capacitor charging time is controlled by adjusting a bias current IB1, a bias current IB2, a reference voltage V1, and a reference voltage V2 or adjusting values of capacitors C1 and C2. In this way, a highest output frequency of a pulse generator is limited, so as to reduce hardware system overheads.