The MC10EL/100EL33 is an integrated 4 divider. The differential clock inputs and the VBB allow a differential, single-ended or AC coupled interface to the device. If used, the VBB output should be bypassed to ground with a 0.01F capacitor. Also note that the VBB is designed to be used as an input bias on the EL33 only, the VBB output has limited current sink and source capability.