Abstract: There is disclosed a power amplifier includes an in-phase power splitter generating two split signals from an input signal, and two amplifiers capable of operating in different modes. The split signals are provided as respective inputs to the two amplifiers which are coupled through transmission lines such that as the first amplifier approaches the maximum power it can produce, the output from the second amplifier begins to contribute to the power amplifier output and supplements and modifies the power provided by the first amplifier thereby extending the range of input power over which the power amplifier delivers output power.

Abstract: A dynamic laser diode drive circuit is formed so that the gain of the final gain stage is controlled in association with the level of the drive current supplied to the laser diode. In particular, the current sources associated with the final gain stage and the output stage and commonly controlled so that the gain tracks the current level. That is, in situations required a relatively low current, the gain is minimized to prevent overdriving the output stage (a situation common in prior art arrangements). When a larger laser drive current is required, the gain of the final stage is adjusted to increase the output from this stage and provide a sufficient voltage differential to drive the output stage.

Abstract: A preamplifier overload control circuit which enhances the dynamic range of the preamplifier. Separate paths shunt corresponding DC and AC components of the signal from an electro-optical device away from the preamplifier input. The amount of shunting in both paths are controlled by a common control signal, here the average DC value of the signal, such that substantially all of the DC signal is shunted away from the preamplifier input.