A Low - Power Architecture Forphase - Splitting Passband Equalizer 1

A low-power architecture for phase-splitting passband equalizer (PSPE) is proposed in this paper. Carrierless AM/PM (CAP) transmission scheme, which is a standard for numerous broadband communication systems including ATM-LAN networks, employs PSPE at the receiving end to combat channel distortion and crosstalk. The conventional PSPE requires two independent adaptive lters that form the in-phase and the quadrature-phase equalizers. The proposed equalizer on the other hand, requires only one adaptive lter that forms the in-phase equalizer. The reduction in complexity is achieved by exploiting the Hilbert relationship between the in-phase and quadrature-phase equalizers. The quadrature-phase equalizer is replaced by a Hilbert transformer and an FIR lter whose coeecients are same as that of the in-phase equalizer. An analytical expression to estimate the possible degradation in signal-to-noise ratio at the output (SNR o) of the equalizer due to the use of nite length Hilbert transformer is derived. It is shown that, by employing the proposed receiver architecture in a 51:84Mb=s ATM-LAN environment, (i) a net saving in power is obtained as long as the length of the Hilbert lter is less than 130, (ii) a saving of up to 20% can be achieved with a degradation of less that 0.5dB. Furthermore, the proposed structure has the added advantage of resulting in fewer erroneous solutions when employed in a blind startup scenario.