10-GHz current-mode 1st- and 2nd-order allpass filters on 130nm CMOS

Novel CMOS wide-bandwidth 1^st- and 2^nd-order current-mode allpass filters are proposed in this paper. The 1^st-order filter consists of only one transistor, two resistors and one grounded inductor. An addition of one capacitor converts the 1^st-order filter into a 2^nd-order filter. A 1^st-order allpass filter with delay of approximately 33 ps and pole-zero location of 10 GHz is designed to confirm the circuit operation. The location of the pole-zero pair is confirmed with a current-mode quadrature oscillator based on the proposed allpass filter. A 2^nd-order filter with maximum achievable delay-bandwidth-product is designed to achieve a group delay of approximate 60 ps across a 10 GHz bandwidth. The performances of the wide-band allpass filters and current-mode quadrature oscillator are obtained in IBM 130-nm CMOS technology.