Differential Sawtooth Generator With Feedback Amplitude Control
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Solution Overview
Problem
Existing sawtooth generators face accuracy issues due to variations in resistor and capacitor values during the fabrication process, leading to unacceptable variations in sawtooth signal amplitude.
Innovation Solution
A dual differential sawtooth signal generator system that includes two sawtooth voltage generators, a comparator, and a dual charge pump, where the comparator compares the positive and negative sawtooth signals to control the feedback currents provided by the dual charge pump, ensuring the same absolute value for both source and sink currents to stabilize the sawtooth amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple charging circuit is used for the sawtooth generator, then the device complexity is reduced, but the manufacturing precision of the sawtooth signal amplitude deteriorates due to component variations
Solution Approach 1:
The patent implements a feedback mechanism where the sawtooth signal amplitude is continuously monitored and compared against a reference value. The feedback loop adjusts the charging current dynamically to compensate for component variations, thereby maintaining precise amplitude control without requiring complex manual trimming circuits.
Solution Approach 2:
The patent changes the operating parameters of the charging circuit by using variable resistance elements or adjustable current sources that can be dynamically modified. This allows the circuit to adapt to component variations and maintain precise sawtooth amplitude despite manufacturing tolerances in fixed components.
2Manufacturing precision
If trimming is added to adjust the sawtooth magnitude, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements a self-adjusting mechanism where the circuit automatically compensates for amplitude deviations without external intervention. The trimming function is integrated into the operational feedback loop, allowing the circuit to self-correct for component variations dynamically during operation, eliminating the need for external trimming potentiometers or adjustment circuits.
3Ease of manufacture
If component values are fabricated with standard tolerances, then the ease of manufacture is improved, but the reliability of the sawtooth amplitude deteriorates
Solution Approach 1:
The patent employs dynamically adjustable parameters in the charging circuit, such as variable current sources or programmable resistance values. This allows the system to compensate for standard tolerance variations in fabricated components by adjusting operating parameters in real-time, thereby maintaining reliable amplitude performance without requiring tight manufacturing tolerances.
Solution Approach 2:
The feedback mechanism continuously monitors the actual sawtooth amplitude and adjusts the charging parameters to compensate for component variations. This closed-loop control ensures that standard tolerance components can be used while maintaining reliable and consistent amplitude output, as the feedback system corrects for deviations caused by component variations.
Data Source
AI summary
A dual differential sawtooth signal generator includes a first sawtooth voltage generator that has a first capacitor and a second capacitor that are alternately charged with a feedback control source current from a low voltage reference voltage level. A second sawtooth voltage generator has a first discharge capacitor and a second discharge capacitor that are alternately discharged with a feedback control sink current from a high voltage reference voltage level. The output signals of the two sawtooth voltage generators are compared to control a phase frequency comparator that provides signals to control a dual charge pump that provides the feedback control source current and that provides the feedback control sink current.