A 100 Mb/s BiCMOS adaptive pulse-shaping filter

With the growing demand for high-speed transmission of digital data, there is a challenge for utilizing the existing copper plant as the transmission medium, especially for short-hop links. This medium offers a lower cost to a fiber medium, but requires more sophisticated electronics to account for electromagnetic emissions, cross-talk, and cable loss. These include pulse shaping filters, cross-talk cancelers, and equalizers. To maintain system cost at a minimum, analog solutions are preferred. A continuous-time tunable biquad implemented in a 0.8 /spl mu/m BiCMOS process and configured as an adaptive pulse-shaping filter is described. The biquad is tunable over the range 10-230 MHz with variable Q factors. It is composed of five transconductance-C integrators each dissipating a static power of 10 mW at 5 V. A method for adapting the filter's pole-frequency and Q-factor while servicing 100 Mb/s NRZ data is presented together with experimental results.