Title :
Chopper-stabilized high-pass sigma delta modulator utilizing a resonator structure
Author :
Ishida, Koichi ; Fujishima, Minoru
Author_Institution :
Dept. of Electron. Eng., Univ. of Tokyo, Japan
Abstract :
A chopper-stabilized high-pass sigma delta modulator (SDM) utilizing a resonator structure for the reduction of low-frequency noise, such as dc offset, thermal drift, and 1/f noise, is presented. The high-pass SDM has a zero of a noise transfer function at half of the sampling frequency and is stabilized by chopper modulation. Since the first integrator of the proposed modulator has a large closed-loop gain, no pre-amplifier is required even when the input signal is small, which is suitable for low-power applications. The signal-to-noise ratios (SNRs) and power dissipations of a high-pass modulator and a conventional modulator have been numerically analyzed.
Keywords :
1/f noise; choppers (circuits); circuit noise; low-power electronics; poles and zeros; sigma-delta modulation; thermal noise; transfer functions; 1/f noise; chopper modulation; chopper-stabilized high-pass sigma delta modulator; dc offset; first integrator; large closed-loop gain; low-frequency noise reduction; low-power applications; noise transfer function; numerical analysis; power dissipations; resonator structure; sampling frequency; signal-to-noise ratios; thermal drift; zero; Choppers; Delta modulation; Delta-sigma modulation; Frequency; Low-frequency noise; Noise reduction; Power dissipation; Sampling methods; Signal to noise ratio; Transfer functions;
Journal_Title :
Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on
DOI :
10.1109/TCSII.2003.816932
