9.1 INTRODUCTION

In this chapter we study models that are valid in a wider frequency range than the five-capacitance quasi-static model of Chap. 8. ^{[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55]} The first model considered is what will be called the complete quasi-static model. This model represents an attempt to take every possible advantage of the quasi-static assumption, and gives an improved upper frequency limit of validity. Beyond that limit, though, the model becomes very inaccurate. It is then necessary to consider non-quasi-static models. Such models will be considered after a general discussion of y-parameter models. A comparison of all models presented will be performed. Noise at high frequencies will then be considered. The chapter will conclude with a discussion of modeling for radio-frequency (RF) applications, including the effects of extrinsic elements.

All effects considered in this chapter will be understood to be for the intrinsic part of the transistor (see Fig. 7.1) except in Secs. 9.3 and 9.6. No impact ionization is assumed to be present.