Performance of modulation-doped charge-coupled devices (MD-CCD's) in the microwave and millimeter-wave bands

A two-phase, modulation-doped charge coupled device (MD-CCD) has been characterized by both phase shift and charge transfer efficiency (CTE) measurements from 1.25 MHz to 16.4 GHz. Both two-dimensional transient simulations and experimental evidence support the conclusion that the cutoff frequency for transport of discrete charge packets emulates the cutoff frequency of small signal HEMT devices in the short gate length regime. These simulations predict a CTE of almost 0.999 at 40 GHz for an In/sub 0.53/Ga/sub 0.47/As channel device. The device is fabricated using conventional MMIC processing techniques. In addition, measurement methods used for characterization of a prototype 5-stage delay line chip agree well with simulations using a new CCD SPICE model.<
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