A 1 GHz continuous-time sigma-delta A/D converter in 90 nm standard CMOS

A 1 GHz continuous-time sigma-delta A/D modulator is presented. It is designed in a standard 90 nm CMOS technology. The 1-bit modulator achieves an accuracy of 10 bits in a signal bandwidth of 8 MHz. This paper focuses on the challenges the designer faces when the sampling speed increases and the supply voltage lowers. It is shown that a G_mC architecture is the most power efficient filter implementation for broadband conversion. Here, the power consumption is determined by thermal noise requirements. Finally, the timing of the feedback pulse is controlled. This ensures an improved stability of the 1 GHz modulator.