A capacitor bank for use in a medical device is provided. Through selective control over the individual capacitors employed in the bank, a low ESR can be achieved without adversely impacting other properties of the resulting medical device. More particularly, at least one capacitor in the bank may contain a solid electrolytic capacitor element that includes an anode and a solid electrolyte overlying the anode. The anode includes an anodically oxidized, sintered porous pellet and the solid electrolyte includes a plurality of conductive polymer particles.