Output Device Transient Response via Dual Driver RC Circuit
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Solution Overview
Problem
Regulator ICs face challenges in maintaining a nonlinear transient response characteristic when load current changes abruptly, often resulting in increased current consumption and potential output voltage deviations due to high input offset deviations and additional reference voltage generating circuits.
Innovation Solution
The proposed output device includes an output transistor, a first driver to align the feedback voltage with a reference voltage, an RC circuit with a capacitor and resistor connected to ground, and a second driver that adjusts the output current based on the potential difference across the resistor, reducing current consumption and improving transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gain of the voltage amplifier is increased or the drive current of the transistor is steadily increased, then the transient response characteristic of the output is improved, but the current consumption is increased
Solution Approach 1:
The patent implements dynamic control by switching between two operational modes: a first voltage amplifier for normal operation and a second voltage amplifier with higher gain for transient periods. This dynamic switching allows the system to adapt its amplification strength based on load conditions, achieving fast transient response only when needed rather than continuously, thus reducing overall current consumption while maintaining improved transient response characteristics during critical moments.
Solution Approach 2:
The patent changes the gain parameter of the voltage amplifier dynamically by selecting between two different amplifiers with different gain values. The second voltage amplifier has a higher gain than the first, and this parameter change is triggered during transient periods when load current changes abruptly. This parameter switching enables the system to optimize transient response without permanently increasing current consumption associated with high-gain operation.
2Speed
If both the voltage amplifier 16 and the voltage amplifier 22 are provided to compare the direct current voltage, then the transient response characteristic can be improved, but the input offset deviation increases and the operating point fluctuates
Solution Approach 1:
The patent segments the voltage amplification function into two distinct voltage amplifiers with specialized roles. The first voltage amplifier handles normal steady-state operation with lower gain, while the second voltage amplifier with higher gain is activated only during transient periods. This segmentation allows each amplifier to be optimized for its specific function, reducing the impact of input offset deviations on overall system performance by limiting the high-gain amplifier's operation to transient conditions only.
Solution Approach 2:
The patent employs periodic or transient-based activation of the second voltage amplifier. Rather than operating both amplifiers continuously, the system switches to the second amplifier only during transient periods when rapid response is needed. This periodic activation pattern minimizes the accumulation of offset errors and prevents continuous operation at high gain, thereby reducing input offset deviation impact while still achieving improved transient response characteristics when required.
3Speed
If a capacitor is inserted and connected in series between the output terminal and the input terminal of the differential amplifier circuit, then the high speed response can be achieved, but the current consumption increases due to the additional reference voltage generating circuit
Solution Approach 1:
The patent extracts and eliminates the need for an additional reference voltage generating circuit by utilizing the existing feedback voltage as one input to the second voltage amplifier. Instead of requiring a separate reference voltage source to bias the differential amplifier, the invention uses the feedback voltage directly, thereby removing the unnecessary current consumption associated with generating an additional reference voltage while maintaining the high-speed response capability through the capacitor-based transient detection mechanism.
Data Source
AI summary
An output device includes an output transistor that outputs an output current, a first driver that drives the output transistor so that a feedback voltage of an output voltage of the output transistor is in agreement with a reference voltage, an RC circuit that has a capacitor connected to the ground and a resistor connected in series to the capacitor, and a second driver that drives the output transistor to increase the output current when a potential difference between ends of the resistor, generated by the feedback voltage supplied between ends of the RC circuit, is increased by a decrease of the output voltage.