On-Chip Condition-Adaptive Δ f3 EMI Control for Switching Power ICs

With perpetual electrification and highly dynamic operations, modern automotive ICs face unprecedented electromagnetic interference (EMI) challenges. To address such, this article presents a condition-adaptive
$\Delta f^{3}$
EMI control for automotive power circuits, which coordinates integral spread-spectrum modulation (SSM) schemes to regulate EMI adaptively in response to drastic condition changes of input voltage
$V_{\mathrm {IN}}$
and load current
$I_{\mathrm {LOAD}}$
. Specifically, a
$\Delta f_{\mathrm {SW,UP/DN}}$
spread control technique steers the
$\Delta f_{\mathrm {SW}}$
spread direction according to
$V_{\mathrm {IN}}$
, while a
$\Delta f_{\mathrm {SW}}$
spread range modulation scheme adjusts the
$\Delta f_{\mathrm {SW}}$
range according to
$I_{\mathrm {LOAD}}$
. Meanwhile, a
$\Delta f_{\mathrm {SW}}$
adaptive multi-rate (MR) SSM scheme prevents spectrum overlap spikes. With the three distinct
$\Delta f_{\mathrm {SW}}$
-focused control modules working cohesively, we name the overall EMI control as the
$\Delta f^{3}$
EMI control in this work. In addition, to avoid high-energy EMI from entering the audible frequency range, a modulation frequency
$f_{M}$
envelope tracking scheme is also developed. Demonstrated in an automotive-use GaN switching power converter, this work was fabricated using a 180-nm HV BCD process. It auto-extends
$\Delta f_{\mathrm {SW}}$
from 10% to 32% and reduces EMI by 17.2 dB to counteract
$I_{\mathrm {LOAD}}$
elevation from 200 mA to 1 A. Meanwhile, it can down-spread
$f_{\mathrm {SW}}$
adaptively by the MR-SSM with a 16.3 dB reduction in response to a
$V_{\mathrm {IN}}$
increase from 12 V to 24 V without causing overlap spikes.