A 1.25mW 3rd-order Active-Gm-RC 250MHz-bandwidth analog filter based on power-stability optimization

In this paper a 250MHz-bandwidth continuous-time low-pass filter is presented. The filter is based on Active-G_m-RC biquadratic cell. With respect to Active-G_m-RC, this filter exploits an additional input RC-net, increasing the low-pass filtering order up to 3, while maintaining single-Opamp topology. In particular, Opamp frequency response has been optimized, exploiting a proper algorithm, that allows to minimize power and maximize loop gain phase margin. A prototype of the filter has been designed in CMOS 0.13μm technology, complying with ultra-wide-band receivers specifications. The filter consumes 1.2mW, while processing a 0.7V_zero-peak differential signal, and maintaining noise power spectral density under 237μV_rms. The overall Signal-to-Noise-Ratio is 65dB.