A clock signal preamplifier comprises complementary pairs of differentially coupled transistors, with an output signal coupled to an inverter further comprising a totem-pole arrangement of complementary MOSFET transistors. The input signal to the preamplifier is typically sinusoidal, and the output signal is rectangular. Preferably, the differentially coupled transistors are bipolar, and a pair of diode clamper circuits with bipolar transistors is preferably coupled to the complementary pairs of differentially coupled transistors. A reference voltage source is coupled to the control terminals of the clamper transistors. A reference voltage source, which preferably comprises a totem-pole arrangement of complementary MOSFET transistors with its output node is coupled to its input node, provides a reference voltage for the diode clamper circuits. Preferably, MOSFET transistors of the reference voltage source and MOSFET transistors of like kind of the inverter are configured to have substantially identical threshold voltages.