A current-mode continuous-time filter for software defined radio solutions

摘要

A 3rd-order continuous-time current-mode filter in 65 nm CMOS technology is presented. The filter has a switchable cut-off frequency between 1.1 and 4.4 MHz and is designed for software defined radio on chip (SDR) solutions. An innovative extension to structures in literature is proposed, that allows saving chip area at low cut-off frequencies. Furthermore a mathematical estimation is presented to show the usability of the structure. The realized chip has an active area of 350 μm × 220 μm and consumes 12.3 mW at 1.2 V. The dynamic range for a bandwidth of 1.1 MHz is 77.2 dB, the in-band output current noise is 31.16 pA/Ö{Hz}31.16,hbox{pA}/sqrt{hbox{Hz}} and the IIP3 is 1.8 mA_p.