The Development of an ATE System for `On-Wafer´ Evaluation of the Microwave and D.C. Characteristics of GaAs MMICs

An automatic test equipment (ATE) is described which is capable of the `on-wafer´ d.c. and microwave characterisation of GaAs monolithic microwave integrated circuits (MMICs). The ATE hardware implementation and the attendant computer control software are discussed in relation to the need to minimise IC production costs. To realise an `on-wafer´ system a microwave probe must be produced to transform the usual 50 ohm coaxial test port dimensions down to the 100 to 150 micron 50 ohm line widths inherent in a MMIC. A novel planar transmission media is presented as a microwave probe with measured performances of SMA connector to probe tip insertion losses of 0.3 dB at 2 GHz and 2 dB at 12 GHz. Input return losses of the probe are better than -15 dB to 16 GHz with interchannel crosstalk below -30 dB to 8 GHz and -20 dB to 18 GHz. To illustrate the calibration and use of the probe system results are given of wafer measurements on S-Band phase shifter MMICs.