Filters and Components With Inductance Cancellation

Abstract

Electrical filters are important for attenuating electrical ripple, eliminating electromagnetic interference (EMI) and susceptibility, improving power quality, and minimizing electromagnetic signature. Capacitors are critical elements in such filters, and filter performance is strongly influenced by the capacitor parasitics. This paper introduces a new design technique that overcomes the capacitor parasitic inductance that limits filter performance at high frequencies. Coupled magnetic windings are employed to effectively cancel the parasitic inductance of capacitors, and to add inductance in filter branches where it is desired. The underlying basis of the new technique is treated in detail, and its application to the design of both discrete filters and integrated LC filter components is described. Numerous experimental results demonstrating the high performance of the approach in both discrete filters and integrated filter elements are provided.

Analysis of Output Characteristics of Buck Converter

“…For deep understanding of the closed-loop input impedance characteristics of the converter, establish voltage-mode control of the synchronous rectifier BUCK converter model [7][8][9] and simulation, as shown in Figure 3;assuming the efficiency of the inverter is 100%:…”

Parasitic capacitance cancellation in filter inductors

“…The topology of the filter network that is created [e.g., Fig. 3(b)] is identical to coupled inductor filter structures that have been used widely for everything from notch-filtering [11], [12] to "zero ripple" filters [13]- [17] to filters incorporating parasitic inductance cancellation [18], [19]. However, the design goals and component values of these other circuit implementations are vastly different from the case considered here.…”

Inductance compensation of multiple capacitors with application to common- and differential-mode filters

“…In this new figure, the differential capacitor C X is fitted with two inductance cancellation coils instead of only one to preserve circuit symmetry. Past work [5] has shown this to be as effective as a single coil, and Fig. 3 shows a photograph of this where the inductance cancellation windings are fabricated on a PCB.…”

“…The size and performance of these filters are often limited by their component parasitics, such as the equivalent series inductance of capacitors and the equivalent parallel capacitance of inductors [1]- [12]. These limitations have generated recent interest in methods for compensating parasitics to increase filter performance [5]- [12]. For example, as shown in [5]- [7], coupled magnetic windings can be used to cancel the effects of capacitor parasitic inductance.…”

“…These limitations have generated recent interest in methods for compensating parasitics to increase filter performance [5]- [12]. For example, as shown in [5]- [7], coupled magnetic windings can be used to cancel the effects of capacitor parasitic inductance. Inductance cancellation windings can be used to reduce the filter volume and cost and/or increase its attenuation performance.…”