MOS-Only and MOS-C Circuits

Abstract

The world of analog IC, the design of which does not include external passive components such as resistances, capacitances, or inductances, has attracted a great deal of interest over the last two decades. This kind of circuits, which consist of only MOSFETs, is called as MOSFET-only (MOS-only) structures. Rapid growth of demands on designs having low cost, low power, and small chip area requires new innovative solutions including MOS-only and MOS-C structures. In this respect, it is important to present new opportunities in MOS-only schemes to improve previously proposed structures in this area. In this chapter, novel MOS-only and MOS-C structures will be presented with promising performances regarding operating frequency range, power consuming, low cost, and small chip area issues. A MOS-only active filter makes use of the intrinsic parameters, gate-to-source capacitance (C_gs), and transconductance (g_m) of a MOS transistor. Even though many filter designs, which incorporate active elements, are reported in the literature, they bring big chip area and restricted operating frequency owing to including high numbers of transistors. In this respect, MOS-only filters can be used to overcome these limits due to the fact that they enable to operate at higher frequencies and have smaller chip areas.

In this chapter we propose a design automation method for only MOS structures by giving four design examples. Our proposed automation flow focuses on saturation region’s small signal equations in order to eliminate these limits by means of polynomial models.

The presented MOS-only and MOS-C circuits based on 0.18 μm TSMC environment in this chapter are easily implementable for encrypted communication or FM band applications, where low power consumption and small chip area are very crucial. Besides, most of the proposed circuits are very compact structures, which can be controlled with only a single voltage port for a wide range of operating regions. Noise, THD results, and Monte-Carlo analyses contribute to their promising characteristics as well.