Inductor Current Emulator Circuit Integrates Signal Differences
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Solution Overview
Problem
Conventional inductor current emulator circuits for switching regulators require complex designs and high manufacturing costs due to the need for extra components like sample and hold circuits, making them bulky and expensive, and are difficult to integrate into integrated circuits due to temperature variations and inductor matching issues.
Innovation Solution
An inductor current emulator circuit that generates a ramp signal to emulate inductor current using a ramp signal generation circuit and an emulator control circuit, which integrates differences between a current sense signal and the ramp signal over different durations, allowing for accurate emulation without the need for an RC circuit parallel to the inductor, thus reducing temperature effects and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an RC circuit is used in the inductor current emulator circuit, then the inductor current can be emulated, but the circuit cannot be integrated into an integrated circuit due to matching issues with different inductors
Solution Approach 1:
The patent extracts the RC circuit from the inductor current emulator circuit, eliminating the sensing resistor Rx and sensing capacitor Cx that formed the RC circuit. Instead, the patent uses an operational amplifier-based circuit that directly processes the inductor current signal without requiring an external RC circuit, thereby enabling integration into an integrated circuit while maintaining adaptability to different inductors.
Solution Approach 2:
The patent designs a universal inductor current emulator circuit that can work with different inductor values without requiring reconfiguration. The operational amplifier-based circuit provides a standardized interface that adapts to various inductors through software or control parameters rather than hardware changes, achieving both integrability and versatility.
2Measurement precision
If the sensing resistor and sensing capacitor are designed to match different inductors, then accurate emulation is achieved, but the manufacturing cost increases and the circuit becomes bulky
Solution Approach 1:
The patent merges the functions of the sensing resistor, sensing capacitor, and operational amplifier into an integrated operational amplifier-based circuit. This consolidation eliminates the need for separate RC components while maintaining emulation accuracy, thereby reducing device complexity and component quantity.
Solution Approach 2:
The patent creates a simplified copy of the inductor current waveform using an operational amplifier circuit that directly processes the current signal without requiring complex RC networks. This approach achieves accurate emulation with fewer components, reducing both manufacturing cost and circuit complexity.
3Reliability
If temperature compensation is added to the inductor current emulator circuit, then temperature stability is improved, but the design becomes more complicated
Solution Approach 1:
The patent employs an operational amplifier-based circuit that inherently provides temperature stability through its high input impedance and low offset drift characteristics. The circuit self-compensates for temperature variations without requiring external compensation components or complex design modifications, thereby maintaining reliability while avoiding increased design complexity.
Data Source
AI summary
An inductor current emulator circuit includes a ramp signal generation circuit and an emulator control circuit. The inductor emulator circuit generates a ramp signal for emulating an inductor current flowing through an inductor of a power stage circuit. The ramp signal generation circuit generates the ramp signal according to a first signal and a second signal. A current sense signal is related a high side switch current flowing through the high side switch or a low side switch current flowing through the low side switch. The emulator control circuit obtains a first difference integration value and a second difference integration value of differences between the current sense signal and the ramp signal during a first duration and a second duration, respectively, to generate the first signal and the second signal, respectively. Center time points of the first duration and the second duration are different from each other.