Method and apparatus for an active negative-capacitor circuit to cancel the input capacitance of comparators

A method of increasing a transfer bandwidth of a differential signal comprising the steps of:

• amplifying a differential input signal to provide said differential signal driving a differential capacitive load between a first node and a second node;
• coupling said first node to a drain of a first transistor and a gate of a second transistor;
• coupling said second node to a drain of said second transistor and a gate of said first transistor;
• coupling a capacitor between a source of said first transistor and a source of said second transistor;
• coupling a first current mirror between a supply voltage and said source of said first transistor;
• coupling a second current mirror between said supply voltage and said source of said second transistor;
• and
• causing said differential capacitive load to be driven in a shorter time period, thereby increasing said transfer bandwidth of said differential signal, wherein
• a first amplifier generates said differential input signal and a plurality of amplifiers receive said differential input signal.

An apparatus comprising:

• a first amplifier coupled to a first node and a second node;
• a differential capacitive load coupled to said first node and said second node;
• said differential capacitive load coupled between drains of transistors in a cross coupled transistor circuit;
• a current source coupled to a source of each transistor;
• a capacitor coupled between said sources of said transistors;
• and
• a plurality of amplifiers coupled to said first and said second node.