Demonstration of a W-band microstrip parallel coupled-line bandpass filter in GaAs technology

In this paper, we demonstrate the performance of a W-band (75-110GHz) parallel coupled-line bandpass filter implemented using a new in-house GaAs microstrip technology. The MMIC process at the University of Glasgow has recently been advanced to incorporate a new process module that includes wafer thinning, through-substrate via etching and backside processing capabilities. This enables the realization of microstrip and grounded coplanar waveguide monolithic circuits for microwave and millimetre-wave applications from a UK source [1]. To demonstrate an example of the high frequency performance of this new process module, a parallel coupled-line bandpass filter has been designed and realized on a 50μm thickness semi-insulating GaAs substrate.