A Low Power 25MHz Switched-Capacitor Resonator for Band-Pass Sigma-Delta Modulator

A low power switched-capacitor double-delay (DD) topology resonator with the resonance frequency of 25 MHz is presented. By using OPAMP sharing technique,double-sampling technique and low power unit circuit blocks,the power consumption of the resonator circuit is minimized. The resonator is fabricated in the SMIC 0.25μm mixed signal CMOS process,the core area of the circuit is 0.09mm². Tested results shown that at sampling frequency of 100MHz,for a 1kHz bandwith signal,the circuit achieves a SFDR of 77dB at resonance frequency of 25MHz,with the static power dissipation being only 10.5mW.