A 0.18μm CMOS Distributed Transversal Filter with Binary-Weighted Gain Cell Design

In this paper, we introduce binary-weighted digital control into the gain cell design of a distributed transversal filter (DTF) to demonstrate the benefits of digitally-assisted RF circuits. By effectively integrating a digital-to-analog converter (DAC) into the gain cell, the new design can improve gain cell´s linearity and hence DTF´s dynamic range. A 5-tap DTF prototype was designed and implemented in a standard 0.18μm digital CMOS technology, using LC artificial transmission lines with on-chip spiral inductors, and gain cells with a quasi-differential amplifier design. 3-bit digital control and analog tuning are both implemented for gain control in each gain cell. The new design achieves a dynamic range of 13 dB. UWB waveforms are generated using the DTF prototype.