A fully active frequency agile filter for multistandard transceivers

The various ways to implement multistandard transceivers are first recalled. It is shown that ease of realization and flexibility are not compatible. All the multistandard transceivers require reconfigurable filters. The theory and the main properties of the frequency-agile active filters recently introduced are recalled briefly in the second part of the paper. It is shown that the current controlled conveyor (CCCII) with switching times less than 3ns is a perfect candidate for implementing frequency-agile filters. The CCCII+ has then been used to design a 2
^nd
order active bandpass frequency-agile filter operating in current-mode. It has four center frequencies, digitally controlled. Its tuning ratio n = f
_0max
/f
_0min
is equal to 5.1, with f
_0max
= 1.2 GHz. To the best of our knowledge, such high values are still never published in the literature.