Experimental CMOS Gm-C Filter Circuits

In this chapter, a total of three continuous-time gm-C low-pass filter implementations are presented, together with their measured performance. They include two evolution versions of fifth-order 240-MHz gm-C filters that were designed and implemented in this work as a part of two single-chip WiMedia UWB direct-conversion receivers in a standard 0.13 and 65-nm CMOS technology, respectively. The 65-nm CMOS filter implementation was also embedded into the I-branch of a single-chip 60-GHz dual-conversion receiver. Correspondingly, a third-order 1-GHz gm-C filter was designed for the Q-branch, rather as a test structure. The 1-GHz design is the third experimental gm-C filter circuit implemented in this work. All three filter implementations are original work in this book. Moreover, all of them were synthesized from lossy LC prototype filters in order to investigate and demonstrate the feasibility of the filter design approach presented in Chap. 4 and, especially, to benefit from the approach. The fifth-order 240-MHz gm-C filter implementations have previously been published in [1] and [2], respectively. The 1-GHz filter implementation has not been published because it did not function properly in the measurements, unlike the simulations. The second evolution version of the two WiMedia UWB receivers and the 60-GHz radio receiver, both implemented in a 65-nm CMOS technology, have been published in [3] and [4, 5], respectively. To the best of the authors’ knowledge, and based on [5], the latter is the first published 60-GHz radio receiver implementation that also contains an analog baseband circuit with an ADC on the same silicon chip with a 60-GHz receiver front-end. In the first evolution version of the two WiMedia UWB receivers, some re-design and, hence, re-processing needed to be done for the RF front-end and therefore, the first UWB receiver implementation has not been published as a complete RF receiver circuit. Instead, each individual circuit block has been published separately. This chapter is mainly based on the contents of the first four references of this chapter.