COT Switching Converter DC Calibration Circuit
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Solution Overview
Problem
Switching converters with constant on time (COT) control architecture require compensation to stabilize output voltage, but existing compensation signals often include a DC component that needs calibration to prevent output voltage from exceeding predetermined values.
Innovation Solution
A novel reference compensating circuit is introduced, comprising an error amplifier, current sinks, a resistor, a current source, and a compensation capacitor, which generates a calibrated compensation reference signal to control the switching converter by alternately turning a main switch and a freewheeling component on and off, thereby eliminating DC errors and stabilizing the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If compensation is added to stabilize output voltage in COT control circuit, then output voltage stability is improved, but DC component in compensation signal causes output voltage to exceed predetermined values
Solution Approach 1:
The patent extracts and removes the DC component from the compensation signal by introducing a calibration circuit that specifically targets and eliminates the DC offset. The calibration circuit separates the DC component removal function from the overall compensation mechanism, allowing the AC compensation to stabilize output voltage while preventing DC-induced voltage excursions beyond predetermined values.
Solution Approach 2:
The patent introduces a calibration circuit as an intermediary element between the compensation circuit and the output voltage. This intermediary circuit processes the compensation signal to remove DC components before the signal affects the output voltage, thereby mediating between the need for compensation and the need to maintain voltage within predetermined limits.
2Measurement precision
If DC calibration is implemented in compensation circuit, then output voltage precision is improved, but circuit complexity increases
Solution Approach 1:
The patent merges the DC calibration function with the existing compensation circuit by integrating the calibration circuit into the feedback loop. Rather than adding a completely separate calibration system, the patent combines DC removal functionality with the voltage compensation mechanism, sharing common components such as operational amplifiers and feedback paths, thereby reducing overall circuit complexity.
Solution Approach 2:
The calibration circuit is designed to perform multiple functions: it removes DC components from the compensation signal, maintains output voltage within predetermined limits, and works continuously during normal operation. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in circuit complexity.
3Speed
If constant on time control is used for fast load transient response, then response speed is improved, but compensation is needed which introduces DC errors
Solution Approach 1:
The patent applies preliminary action by continuously removing DC components from the compensation signal before they can cause output voltage errors. The calibration circuit operates in real-time during constant on time control, proactively eliminating DC offsets as they occur, thereby maintaining both fast transient response and signal accuracy without requiring post-correction mechanisms.
Data Source
AI summary
A reference compensating circuit used in a COT control circuit. The reference compensating circuit has an error amplifier, a first current sink, a resistor, a second current sink, a current source and a capacitor. The error amplifier amplifies the difference between a reference signal and a feedback signal and generates an error signal. Based on the error signal, the first current sink generates a current flowing out from a node of the reference compensating circuit. The resistor receives the reference signal at one terminal. The other terminal of the resistor is coupled to the node. The second current sink sinks a current from the node intermittently. The current source sources a current into the node. The capacitor is coupled between the node and a ground to provide a calibrated compensation reference signal to the COT control circuit.