Abstract

This paper presents the design and experimental results of a nonlinear circuit and a tuned amplifier developed in the same GaAs monolithic microwave integrated circuit (MMIC), used in a 20 Gsymbol/s open-loop clock recovery unit. The nonlinearity is an unbalanced structure and its input stage performs the necessary signal formatting to reduce the recovered clock jitter, avoiding the use of additional pre-filtering. Both circuits were integrated in the same MMIC in order to improve the reliability, performance and to reduce the size and cost. Performance assessment of the clock recovery unit consisting of the two designed circuits and a high-Q bandpass filter is carried out, considering two different line codings, binary NRZ (20 Gbit/s) and 4-level (40 Gbit/s).