Output buffer with time varying source impedance for driving capacitively-terminated transmission lines

An output buffer for driving a capacitively-terminated transmission line produces a waveform which comprises a first portion during which the waveform transitions from a voltage V to a voltage V; a second portion during which it remains fixed at V; a third portion during which it transitions to a voltage V; and a fourth portion during which it remains fixed at V. The waveform is created within a unit interval whenever successive data bits transition between logic states. The first and second portions are generated with circuitry arranged such that V is maximized by reducing the buffer's output impedance. The fourth portion is generated with circuitry which has a non-zero output impedance preferably equal to the transmission line's characteristic impedance, to absorb transitions reflected back to the source circuitry by the capacitive termination.