A wide tuning range low-pass Gm-C filter for multi-mode wireless receivers with automatic frequency calibration

A 4^th-order channel selection low-pass Gm-C filter for multi-mode wireless receivers is presented. The filter is designed with a Chebyshev prototype and supports different wireless communication modes including W-CDMA, TD-SCDMA, LTE, and IEEE802.11a/b/g wireless-LANs. A linear operational transconductance amplifier (OTA) which has variable transconductance is used to achieve the wide tuning range of the filter. Implemented in the SMIC 0.13μm CMOS process, the measurement results show that the filter can operate successfully over a cutoff frequency range of 1MHz to 15MHz, Which is compliant with the requirements of different wireless communication modes. The out-of-band input 3^rd order intercept point is 15.2dBm. The input referred noise is 17.4nV/Hz^1/2 and the noise figure is 25.6dB. The power consumption is 11.4mW at 15MHz cutoff frequency under a 1.2V supply voltage. The size of the proposed filter is 1.5mm×1mm.