Abstract: An operational amplifier having an extremely high gain-bandwidth product. The amplifier includes a gain cell with an active negative resistance circuit made up of two matched NPN transistors (18 and 20) with their bases cross-connected to their collectors, and with a differential pair of NPN transistors (14 and 16) having their emitters degenerated through the active negative resistance circuit. The value of the negative resistance is chosen to negate other resistance values in the denominator of a fraction expressing overall amplifier gain, which is therefore maximized. Since no PNP transistors are needed to maximize gain in the amplifier, NPN transistors can be used exclusively, and the amplifier can be more conveniently fabricated in integrated-circuit form, with a desirably wide bandwidth.