3-level bridge driver with single supply and low common mode EMI emission

摘要

In one embodiment, a circuit, having a single supply, is provided to transmit a wireless signal with low common mode electromagnetic interference (EMI) emission. The circuit can achieve common mode attenuations of 40 dB or greater as a result of the symmetric built circuit. Also included is a system that includes a transmission circuit and a receiver circuit, and a method of using such a system.

主权项

1. A transmission circuit comprising:
a resonance circuit, located between power-receiving terminals, wirelessly transmitting an information signal to an external circuit; a capacitor and a resistor connected together in series between the power-receiving terminals; and switching circuitry configured and arranged for:
generating different levels of square wave voltage signals by controlling coupling of the resonance circuit to power supply terminals, the different levels of square wave voltage signals including upper-level voltage signals, lower-level voltage signals, and mid-level voltage signals, to provide energy to the resonance circuit and, in turn, causing wireless transmission of the information signal; and when generating the mid-level voltage signals:eliminating DC current paths between power-receiving terminals and the power supply terminals,shorting the power-receiving terminals together thereby directing movement of charge stored in the resonance circuit from one of the power receiving terminals to the other power receiving terminal to generate the mid-level voltage signal, andpausing during switching to create a break-before-make gap, wherein the capacitor and resistor are in a current path which is connected in parallel with the resonance circuit and which conducts current during the break-before-make gap.