Multiphase DC-to-DC Converter Cross-Channel Blanking
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Solution Overview
Problem
Noise spikes caused by circuit parasitics and high current gate drive pulses in multiphase DC-to-DC switching power converters lead to faulty current measurements, affecting the operation of buck converters.
Innovation Solution
The implementation of leading-edge and cross-channel blanking in a multiphase synchronous buck converter, where current sense signals are blanked during specific periods corresponding to noise spikes, ensuring accurate current sensing by eliminating noise interference across channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensing is performed during MOS transistor switching, then current measurement capability is improved, but measurement precision deteriorates due to noise spikes from circuit parasitics and gate drive pulses
Solution Approach 1:
The blanking circuit proactively suppresses the current sense signal during predetermined time periods that correspond to MOS transistor switching events. By anticipating when noise spikes will occur (during turn-on and turn-off transitions), the system preemptively blanks the signal to prevent noise contamination, thereby ensuring accurate current measurements during critical switching transitions
Solution Approach 2:
The blanking circuit acts as an intermediary between the current sense circuit and the controller. It conditionally suppresses the current sense signal based on timing relationships with MOS transistor switching, filtering out noise spikes while allowing valid current information to pass through to the controller for proper operation
2Measurement precision
If leading-edge blanking is applied to suppress noise during MOS turn-on, then measurement precision is improved, but loss of time occurs during the blanking period
Solution Approach 1:
The blanking circuit applies partial suppression by selectively blanking the current sense signal only during specific time windows corresponding to noise-prone switching events, rather than continuously blanking. This partial action approach minimizes the loss of time while still effectively removing noise spikes during critical transitions
3Measurement precision
If cross-channel blanking is implemented in multiphase converters, then measurement precision across channels is improved, but device complexity increases
Solution Approach 1:
The blanking circuit is designed to handle multiple functions: it suppresses noise during leading-edge transitions, performs cross-channel blanking to eliminate coupling effects between phases, and works across all MOS transistors in the multiphase converter. This multi-functional design achieves comprehensive noise suppression across all channels while avoiding the need for separate dedicated circuits for each blanking function
Solution Approach 2:
The blanking circuit combines leading-edge blanking and cross-channel blanking functions into a unified timing control mechanism. By merging these functions and using coordinated blanking pulses synchronized with the multiphase switching scheme, the system achieves improved measurement precision across all channels while managing device complexity through functional integration
Data Source
AI summary
A multiphase DC-to-DC synchronous power converter, which has a number of converter channels that generate a corresponding number of current sense signals, blanks the current sense signals in a first converter channel for periods of time that correspond with the actions of the transistors in a second converter channel, where the actions result in noise spikes across the converter that falsely interfere with current sensing in the first converter channel.