Multi-Output DC-DC Pulse Pairing for RF EMI Notching
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Solution Overview
Problem
DC-DC converters, particularly pulse frequency modulation (PFM) converters, generate high-frequency noise that causes electromagnetic interference (EMI), which can disrupt the operation of nearby RF receivers, especially those sensitive to weak wireless signals.
Innovation Solution
A system comprising a driver circuit, selection circuit, and arbiter that controls the delivery of current pulses to load nodes, using a pulse pair mode to regulate voltages and minimize interference by creating notches in the frequency spectrum, with a microcontroller enabling pulse pair mode when an RF receiver is active and disabling it when inactive, and a calibration circuit to control pulse duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If PFM converter is used to maximize efficiency, then energy conversion efficiency is improved, but electromagnetic interference to RF receiver increases
Solution Approach 1:
The patent implements pulse pairing where current pulses are delivered in sequential pairs with specific timing relationships. The first pulse pair is delivered to a first output node and the second pulse pair is delivered to a second output node, creating periodic switching patterns that generate notches in the frequency spectrum at RF receiver frequencies, thereby reducing electromagnetic interference while maintaining PFM efficiency benefits
Solution Approach 2:
The patent dynamically changes switching parameters including pulse timing, pulse duration, and pulse delivery sequence based on receiver activity detection. When a receiver is active, the system adjusts the pulse pairing parameters to create frequency notches that suppress EMI at the receiver's operating frequency, while maintaining efficient power conversion
2Reliability
If switching operations are performed to regulate voltage, then voltage regulation is improved, but high frequency noise generation increases
Solution Approach 1:
The patent uses periodic pulse pairing with controlled timing to deliver current to output nodes. By structuring the switching operations as coordinated pulse pairs with specific intervals and sequences, the system maintains effective voltage regulation while the periodic nature creates spectral notches that reduce high frequency noise at problematic frequencies
3Object-affected harmful factors
If pulse pair mode is enabled to reduce EMI, then electromagnetic interference is reduced, but device complexity increases
Solution Approach 1:
The patent detects receiver activity in advance and pre-configures the pulse pairing mode before EMI becomes problematic. The microcontroller monitors receiver status and enables the coordinated pulse delivery scheme proactively, allowing the system to maintain simple operation during normal conditions while automatically transitioning to pulse pair mode when needed
Solution Approach 2:
The system automatically detects receiver activity and self-adjusts its switching mode without external intervention. The microcontroller monitors receiver presence and autonomously enables or disables pulse pair mode, and the control circuit automatically coordinates pulse delivery to appropriate output nodes, reducing the need for complex external control mechanisms
Data Source
AI summary
In one embodiment, a method includes: enabling a pulse pair circuit of an integrated circuit in response to determining that a receiver associated with the integrated circuit is active; identifying that at least one comparator of a multi-output DC-DC converter trips, the DC-DC converter having a plurality of comparators each to compare a regulated voltage output by the DC-DC converter to a corresponding reference voltage; and generating, in the pulse pair circuit, a control pulse pair according to the tripped output, and driving a driver circuit of the DC-DC converter using the control pulse pair.