DC-DC Converter PWM Modulation for Fast Clock and Load Response
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Solution Overview
Problem
Conventional DC-DC converters are limited in achieving high clock frequencies and fast load change responses, with ripple injection type converters for hysteresis control not fully meeting market demands for rapid frequency adjustments and efficient operation.
Innovation Solution
A DC-DC converter design incorporating a reference voltage generating circuit, modulation clock signal generating circuit, comparator, modulator, and driver, which modulates the reference voltage in synchronization with a modulation clock signal to produce a PWM signal responsive to output voltage, allowing for increased switching frequency and rapid load change response without the limitations of conventional hysteresis converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional DC-DC converter circuit technology is used, then circuit stability is maintained, but clock frequency is limited to 3-4 MHz and load change response is slow
Solution Approach 1:
The patent changes the control parameter from conventional hysteresis-based control to PWM modulation with ripple injection. By modulating the reference voltage in synchronization with a modulation clock signal and comparing it with feedback voltage, the system achieves higher clock frequencies (exceeding 3-4 MHz) while maintaining stability through the feedback mechanism.
Solution Approach 2:
The patent implements a feedback control mechanism where the output voltage is fed back and compared with a modulated reference voltage. This feedback loop enables the system to respond rapidly to load changes while maintaining stable operation at higher clock frequencies, resolving the contradiction between speed and stability.
2Speed
If ripple injection type DC-DC converters for hysteresis control are used, then load change response is improved, but clock frequency adjustment capability is limited
Solution Approach 1:
The patent introduces a dynamic PWM modulation scheme where the reference voltage is modulated in synchronization with a modulation clock signal. This dynamic control approach allows the converter to rapidly respond to load changes while simultaneously enabling flexible frequency adjustment, as the modulation frequency can be varied to match different operating conditions.
Solution Approach 2:
The patent employs periodic PWM modulation with ripple injection at a specific frequency. This periodic action enhances load change response by creating controlled oscillations that accelerate the response time, while the modulation frequency can be adjusted to provide versatility across different operating scenarios.
3Speed
If switching frequency is increased, then clock operation speed is improved, but circuit size increases
Solution Approach 1:
The patent changes the control methodology to PWM modulation with synchronized reference voltage modulation. This approach allows higher switching frequencies to be achieved without proportionally increasing circuit size, as the modulation technique improves the utilization efficiency of the switching elements and reduces the required size of passive components.
Data Source
AI summary
The DC-DC converter includes a reference voltage generating circuit that generates a reference voltage. The DC-DC converter includes a modulation clock signal generating circuit that generates a modulation clock signal. The DC-DC converter includes a modulator that performs modulation of the reference voltage in synchronization with the modulation clock signal and outputs a resulting reference signal. The DC-DC converter includes a first comparator that compares the reference signal and a first feedback signal, which is based on the output voltage, and outputs a signal based on a result of the comparison. The DC-DC converter includes a driver that shapes a waveform of a PWM signal, which is based on the signal output from the first comparator, and outputs the PWM signal with the shaped waveform to the control node.