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.

The effects of DC offsets on four variations of the stochastic gradient algorithm are analyzed to determine the most appropriate algorithm for hardware implementation. The output mean squared error (MSE) performance in the presence of DC offsets is evaluated and compared with computer simulations for each of the algorithms assuming a Gaussian input distribution.>