Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
Ripple Cancellation Circuit in Switching DC-DC Converters
Technology Category/Market
Category – Electronics & Circuits, Integrated Circuits (ICs)
Applications – Switching DC-DC converter for power management Integrated Circuits, Voltage regulators.
Market- The global DC-DC converter market is projected to grow from $10.04 billion in 2022 to $21.92 billion by 2029, at a CAGR of 11.79%.
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Problem Statement
- Switching regulator suffers from large output ripple which makes it unsuitable for noise sensitive applications such as analog and RF.
- Prior techniques used to reduce the output ripple include increasing switching frequency, using large output capacitors or active ripple cancellation.
- Therefore, increasing switching frequency reduces overall efficiency, larger capacitor increase area and increases cost of the module.
- However, this technique requires perfect matching between main inductor and ripple cancellation inductor. Since inductors may easily have 10-20% tolerances, large mismatch between two inductors may result in negligible or no reduction in the output ripple.
- Therefore, a control technique to cancel the effect of mismatch between two inductors and thereby achieve perfect ripple cancellation in the output voltage is essential.
Technology
- The present invention relates to circuitry and methods for ripple cancellation in switching voltage regulators (refer Fig. 1).
- The ripple cancelling circuit 160 includes an inductor mismatch compensator circuit 150, a ripple cancellation circuit 130, and a pulse width modulation (PWM) controller 124.
- The method of ripple cancelation is based on detecting output ripple and varying supply voltage.
- The method uses a separate supply voltage for the cancellation path.
- The method involves a control technique to cancel mismatch between a ripple cancellation inductor 134 and the main inductor 114 in the circuit to achieve perfect ripple cancellation in the output voltage.
- Since inductor ripple current is proportional to input voltage, any mismatch between the inductors 114, 134 is corrected by increasing or decreasing the input supply voltage.
Key Features/Value Proposition
- The proposed method may be implemented in a multiphase DC-DC converter.
- The advantage of the invention is that the ripple cancellation path may be operated at low voltage resulting in low cost and lesser area high voltage converters.
- Also small inductors and low voltage devices may be used in the ripple cancellation path.
Questions about this Technology?
Contact for Licensing
Research Lab
Prof. Qadeer Ahmad Khan
Department of Electrical Engineering
Intellectual Property
- IITM IDF Ref. 1698
- IN 201841033931
- PCT/IN2019/050656
Technology Readiness Level
TRL- 3
Proof of Concept ready & validated.