100 MHz Low-Power Modulator/Demodulator for Signal Isolation of SiC Gate Driver IC

This paper presents a low-power modulator and demodulator circuits for silicon carbide (SiC) MOSFET gate driver integrated circuit (IC). They have a very simple structure and reduce the pulse-width modulation (PWM) signal error from the external noise such as an electro-magnetic interference (EMI) and supply noise. The modulator adopts a current-starved ring oscillator with a beta-multiplier achieving 1.1/0.54% frequency variation with 150 °C temperature and 100 mV supply voltage change. The demodulator core part consists of only twelve MOSFETs and whole circuits consume 1 mW because of the leakage based operation algorithm. The proposed SiC gate driver is fabricated with $0.35 \mu\mathrm{m}$ BCDMOS process and total power consumption of the mod/demodulator circuit is 0.825/1 mW with 100 MHz carrier frequency.