How doe the output LC filter for a bridge application verses a single-ended application?
A 2-pole output filter consist of an inductor in series with the output and a capacitor going to ground after the inductor. This is the correct design for a single-ended configuration using a 2-pole output filter. When the design is a bridge tied load (BTL) often the same output filter is used; namely an inductor in series with each output and a capacitor to ground after the inductor to ground or four components. For a BTL configuration this is correct but the pole location is not the same. What the filter actually looks like to the output is a capacitor to ground from one output then from ground through a capacitor to the other output. In effect, two capacitors in series or ½ the capacitance value than originally calculated. This is easily solved by connected one capacitor across the load at ½ the calculated value. Each output sees a capacitor so the effect is double the value used is seen in the output filter. The BTL configuration therefore requires a smaller capacitor than the sing
