Multi-phase Voltage Regulator Current Sense Circuit
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Solution Overview
Problem
Current multiphase voltage regulators require complex circuitry, numerous external components, and multiple pins for current sensing, which increases cost, complexity, and sensitivity to parasitic resistances from copper tracks, limiting precision and efficiency.
Innovation Solution
A compact current sense circuit using a minimal number of external components and pins, where the operational amplifier receives the sum of voltage phases from switches through an adder circuit and filtering capacitor, generating a current signal proportional to the total current, independent of parasitic resistances from copper tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistance Rsense is used for current sensing, then precise current reading is provided, but cost increases and current conversion efficiency decreases
Solution Approach 1:
The patent extracts the current sensing function from a separate Rsense resistor and implements it using the existing parasitic resistance of the inductor. This eliminates the need for an additional external resistor component while maintaining sensing accuracy. The inductor's inherent resistance is utilized to generate a voltage signal proportional to the current, which is then processed by the operational amplifier.
Solution Approach 2:
The inductor serves dual purposes: it performs its primary function of energy storage and filtering while simultaneously providing the sensing resistance for current measurement. The parasitic resistance of the inductor, which is normally a source of loss, is repurposed as a useful sensing element, eliminating the need for separate sensing components.
2Device complexity
If regulator parasitic elements are used for current sensing, then cost is reduced, but measurement precision decreases due to sensitivity to single element errors and temperature variations
Solution Approach 1:
The patent combines the current sensing function with the inductor's existing parasitic resistance, merging two functions (energy storage and current sensing) into a single component. This integration eliminates the need for separate sensing resistors and reduces the number of external components while maintaining measurement accuracy through the operational amplifier circuit.
3Measurement precision
If multiple pins are used for current sensing in multiphase regulators, then current measurement capability is improved, but device complexity and pin count increase
Solution Approach 1:
The patent merges the current sensing signals from multiple phases by connecting them in parallel to the non-inverting input of the operational amplifier. This configuration allows the amplifier to sum the currents from all phases automatically, providing total current measurement through a single sensing path and minimal pins, thereby simplifying the interface requirements.
4Measurement precision
If complex circuitry with numerous external components is used, then current sensing capability is improved, but manufacturing cost and sensitivity to parasitic resistances increase
Solution Approach 1:
The patent extracts the current sensing function from complex external circuitry and implements it using the inductor's inherent parasitic resistance combined with a simple operational amplifier configuration. This approach eliminates the need for multiple external sensing components and complex routing, thereby reducing sensitivity to parasitic resistances from copper tracks and simplifying manufacturing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the number of external components and pins required, enhances precision, and provides a fully differential current reading independent of parasitic resistances, improving the reliability and efficiency of the voltage regulator.
Implementation Method 1
An amplifier circuit has a first input for receiving the added voltage from the sense circuit, and generates a current proportional to the total current
Data Source
AI summary
A multiphase voltage regulator provides a voltage to an output terminal. The voltage regulator includes N parallel switches providing respective current phases that are added together to generate a total current for a general load coupled to the output terminal. The voltage regulator also includes N inductive circuits. Each inductive circuit is between an output node of a respective switch and the output terminal. A sense circuit adds the voltages in each of the output nodes of the N switches. An amplifier circuit has an input receiving the added voltage, and outputs a current proportional to the total current. A controller with two pins reads the total current. The two pins are connected to the inputs of the amplifier.