A GaAs signal shaping network with a controlled response from DC to 25 GHz

The authors describe how a GaAs monolithic microwave integrated circuit (MMIC) signal shaping network with a controlled response from DC to 25 GHz was designed, fabricated and tested. The network is a post-detection filter for use in a 15 Gbit/s optical fibre transmission system that uses narrow, soliton like pulses. They begin by outlining the design philosophy that defined the target response. This is followed by a brief description of the GaAs technology used to realise the filter. The impact of the parasitics associated with the technology are outlined which leads onto a description of the optimisation method adopted that includes the process parasitics inside the optimisation loop. Simulation results for the GaAs filter are given followed by measured data to illustrate the very tight control over the frequency response possible with MMIC realisations if care is taken during the design