Abstract: A sharp transition is achieved between pushing and pulling an output current by simultaneously diverting the bias current from a series stacked transistor circuit and from the base of a sink transistor. After the series stacked transistor circuit is kept from conducting output current, the sink transistor allows bias current to drive the other transistor circuit in the stack. Each of the transistor circuits in the stack is associated with a bias current and a sink transistor. The sink transistors and the bottom transistor circuit in the stack have emitters coupled to a floating ground. A switching signal input circuit includes an input transistor and a current mirror. The low input signal from the switching signal input circuit to a control input at a first sink transistor in the drive circuit is clamped relative to the floating ground.