On-Chip Condition-Adaptive Δ f 3 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.