Analog blocks for high-speed oversampled A/D converters

The design of high performance sigma-delta converters involves high frequency operation. This constraint means analog blocks must be carefully designed to meet these requirements. BiCMOS technology offers advantages with respect to CMOS in realising high-speed analog blocks. This paper describes an operational amplifier and a comparator designed in BiCMOS technology. Suitable circuit solutions have been used to obtain the required values for DC gain, gain-bandwidth product and slew-rate. High-level simulations of both low-pass and band-pass oversampled converters indicate that the blocks designed allow a faster clock rate than CMOS and are suitable for operation in switched-capacitor circuits with sampling rate of up to 40 MHz.

[1]  L. Longo,et al.  A 15 b 30 kHz bandpass sigma-delta modulator , 1993, 1993 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[2]  W. Sansen,et al.  A High-Frequency and High-Resolution Fourth-Order ΣΔ A/D Converter in BICMOS Technology , 1993, ESSCIRC '93: Nineteenth European Solid-State Circuits Conference.

[3]  C. D. Thompson,et al.  A digitally-corrected 20b delta-sigma modulator , 1994, Proceedings of IEEE International Solid-State Circuits Conference - ISSCC '94.

[4]  Gabor C. Temes,et al.  A high-resolution multibit Sigma Delta ADC with digital correction and relaxed amplifier requirements , 1993 .

[5]  Richard Schreier,et al.  Decimation for bandpass sigma-delta analog-to-digital conversion , 1990, IEEE International Symposium on Circuits and Systems.

[6]  Bruce A. Wooley,et al.  A 10-bit video BiCMOS track-and-hold amplifier , 1989 .

[7]  M. Snelgrove,et al.  10.7 MHz bandpass delta-sigma A/D modulators , 1994, Proceedings of IEEE Custom Integrated Circuits Conference - CICC '94.

[8]  Bang-Sup Song,et al.  A 4th-order bandpass /spl Delta//spl Sigma/ modulator with reduced number of op amps , 1995, Proceedings ISSCC '95 - International Solid-State Circuits Conference.

[9]  Willy Sansen,et al.  A high-frequency and high-resolution fourth-order /spl Sigma//spl Delta/ A/D converter in BiCMOS technology , 1994 .

[10]  Gabor C. Temes,et al.  Oversampling Delta Sigma Data Converters , 1991 .

[11]  I. Dedic,et al.  A sixth-order triple-loop sigma-delta CMOS ADC with 90 dB SNR and 100 kHz bandwidth , 1994, Proceedings of IEEE International Solid-State Circuits Conference - ISSCC '94.

[12]  Franco Maloberti,et al.  Fundamental limitations of switched-capacitor sigma-delta modulators , 1992 .

[13]  L. Longo.  A 15b 30kHz bandpass sigma-delta modulator , 1993 .

[14]  Willy Sansen,et al.  Design considerations of high-dynamic-range wide-band amplifiers in BiCMOS technology , 1991 .

[15]  S. J. Daubert,et al.  A transistor-only current-mode Sigma Delta modulator , 1992 .

[16]  Bruce A. Wooley,et al.  An 8-bit 200-MHz BiCMOS comparator , 1990 .

[17]  Giuseppe Palmisano,et al.  Sigma-delta modulators for high-resolution and wide-band A/D converter applications , 1994 .