Nonlinear circuit design for 77 GHz automotive applications
Nichtlinearer Schaltungentwurf für 77 GHz-Kfz-Abstandswarnradarsensoren
W-band radar systems for automotive applications have focused interest on cost effective integrated circuits on GaAs. With compact transmit and receive MMICs in coplanar technology, having a chip size of 3 x 2 mm2 each, the required system performance at 77 GHz has been demonstrated . For meeting the targets of high volume markets, two goals are of crucial importance: Minimizing the total chip area necessary for a complete FMCW system at 77 GHz and reliable predictions of the nonlinear circuit performance. Both goals have been achieved in designing and fabricating a very compact integrated transceive MMIC with a 0.15 mu m T-gate PMHEMT process in coplanar technology . An in-house analytical HEMT-model , implemented as symbolically defined device (SDD) in HP-MDS, has been used for performing harmonic balance simulations of the entire multifunction IC, comprising four transistors in the transmit path and up to three devices in the receive path. As will be shown in a more detailed descrip tion of the MMIC's electrical performance below, measured and simulated output power at 77 GHz as well as conversion characteristics agree very well, allowing a detailed in-situ power analysis of the transmit and the receive path.