Title :
A 20bit continuous-time ΣΔ modulator with a Gm-C integrator, 120dB CMRR and 15 ppm INL
Author :
Singh, Gaurav ; Wu, Rong ; Chae, Youngcheol ; Makinwa, Kofi A A
Author_Institution :
Electron. Instrum. Lab., Delft Univ. of Technol., Delft, Netherlands
Abstract :
This paper describes a precision continuous-time sigma-delta modulator for sensor readout applications. Its input stage consists of a high-impedance Gm-C integrator. The nonlinearity of the input transconductor is compensated for by the inclusion of a low-pass filter and an identical transconductor in the feedback path of the single-bit modulator. The second-order modulator achieves 1 μV offset, 120 dB CMRR and 20-bit resolution over a ±40 mV input range at a conversion rate of 10 S/s. It also achieves 15 ppm INL and less than -100 dB THD for AC signals up to 200 Hz. The modulator is implemented in a 0.7μm CMOS process and draws 240 μA from a 5 V supply.
Keywords :
CMOS integrated circuits; circuit feedback; electric impedance; low-pass filters; readout electronics; sigma-delta modulation; AC signal; CMOS process; CMRR; INL; continuous-time ΣΔ modulator; current 240 muA; feedback path; high-impedance Gm-C integrator; identical transconductor; input transconductor nonlinearity; low-pass filter; precision continuous-time sigma-delta modulator; second-order modulator; sensor readout application; single-bit modulator; size 0.7 mum; voltage 1 muV; voltage 5 V; word length 20 bit; CMOS integrated circuits; Frequency modulation; Low pass filters; Noise; Power dissipation; Quantization;
Conference_Titel :
ESSCIRC (ESSCIRC), 2012 Proceedings of the
Conference_Location :
Bordeaux
Print_ISBN :
978-1-4673-2212-6
Electronic_ISBN :
1930-8833
DOI :
10.1109/ESSCIRC.2012.6341366
