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A low-noise preamplifier for fiber-optic systems which uses a GaAs FET as input stage is described. It exhibits high input impedance which is shown to yield a low-noise performance insensitive to 1/f noise, an otherwise dominant component with a GaAs FET input stage. A modified version serves as a broadband general-purpose amplifier terminated at the input and output by 50 /spl Omega/. A novel gain cell is used which yields a significant improvement in the bandwidth. The customary resistive load of the gain stage is replaced by the circuit capacitance at that node, and the resulting integration is cancelled by subsequent differentiation in the output stage.