A 250-MHz cutoff charge-domain baseband filter with improved stopband attenuations

A discrete-time charge-domain baseband filter with a wide bandwidth and improved stopband attenuation characteristics has been implemented with a 90 nm CMOS technology. The proposed zero splitting technique allows the discrete-time charge-domain filter to have attenuation notches at non-integer-divided frequencies of the sampling frequency, thus improving the stopband attenuation characteristics. Measurements show that the 250-MHz cutoff filter achieves an attenuation of 42 dB at 580 MHz, while dissipating 16.6 mW from a 1.2-V supply voltage.