Experimental Validation of a Tuning Algorithm for High-Speed Filters

We report here the results of some laboratory experiments performed to validate the effectiveness of a technique for the self tuning of integrated continuous- time, high-speed active filters. The tuning algorithm is based on the application of a pseudo-random input sequence of rectangular pulses to the device to be tuned and on the evaluation of a few samples of the input-output cross-correlation function which constitute the filter signature. The key advantages of this technique are the ease of the input test pattern generation and the simplicity of the output circuitry which consists of a digital cross- correlator. The technique allows to achieve a tuning error mainly dominated by the value of the elementary capacitors employed in the tuning circuitry. The time required to perform the tuning is kept within a few microseconds. This appears particularly interesting for applications to telecommunication multi-standard terminals. The experiments regarding the application of the proposed tuning algorithm to a baseband multi-standard filter confirm most of the simulation results and show the robustness of the technique against practical operating conditions and noise.