A 4th-order active-Gm-RC reconfigurable (UMTS/WLAN) filter

A fourth-order low-pass continuous-time filter for a UMTS/WLAN receiver of a reconfigurable terminal is presented. The filter uses the cascade of two Active-G(m)-RC biquad cells. A single opamp is used for each biquad and its unity-gain-bandwidth is comparable to the filter cut-off frequency. Thus, the opamp power consumption is strongly reduced w.r.t. other closed-loop filter configurations. The cut-off frequency deviation due to the technological spread, aging and temperature variation is adjusted by an on-chip tuning circuit. The device in a 0.13 mu m CMOS technology occupies a 0.9 mm(2) area and it consumes 3.4 mW and 114.2 mW for the UNITS and WLAN, respectively. The full chip has been designed using an automatic design tool, which is validated by the agreement between the experimental results and the expected performance.