A 14-bit 5MHz continuous-time sigma-delta ADC

A high-speed, high-accuracy, low power continuous-time sigma-delta (CTSD) modulator designed by using SMIC 0.18 μm CMOS technology is presented in the paper. The fifth-order CTSD modulator comprises a fifth-order RC operational-amplifier-based loop filter and 4-bit internal quantization operating at 320 MHz. The techniques of NRZ DAC pulse shaping and half sampling period delay are adopted to reduce clock jitter and delay time sensitivity. The modulator achieves 13.5-bit ENOB at 5 MHz signal bandwidth and OSR is 32. The power consumption of the modulator is 19.8 mW.