Delta-sigma modulators using frequency-modulated intermediate values

Author

Høvin, Mats ; Olsen, Alf ; Lande, Tor Sverre ; Toumazou, Chris

Author_Institution

Dept. of Inf., Oslo Univ., Norway

Volume

32

Issue

1

fYear

1997

fDate

1/1/1997 12:00:00 AM

Firstpage

13

Lastpage

22

Abstract

This paper describes a new first- and second-order delta-sigma modulator concept where the first integrator is extracted and implemented by a frequency modulator with the modulating signal as the input. The result is a simple delta-sigma modulator with no need for digital-to-analog converters, allowing straightforward multibit quantization. Without the frequency modulator, the circuit becomes a frequency-to-digital converter with delta-sigma noise shaping. An experimental first- and second-order modulator has been implemented in a 1.2-μm standard digital CMOS process and the results confirm the theory. For the first-order modulator an input signal amplitude of 150 mV resulted in a signal-to-quantization noise ratio (SQNR) of ≈115 dB at 2 MHz sampling frequency and signal bandwidth of 500 Hz

Keywords

CMOS integrated circuits; frequency modulation; modulators; quantisation (signal); sigma-delta modulation; 1.2 micron; 150 mV; 2 MHz; 500 Hz; CMOS process; delta-sigma modulators; frequency-modulated intermediate values; input signal amplitude; integrator; modulating signal; multibit quantization; sampling frequency; signal bandwidth; signal-to-quantization noise ratio; CMOS process; Circuits; Delta modulation; Digital modulation; Digital-analog conversion; Digital-to-frequency converters; Frequency conversion; Frequency modulation; Noise shaping; Quantization;

fLanguage

English

Journal_Title

Solid-State Circuits, IEEE Journal of

Publisher

ieee

ISSN

0018-9200

Type

jour

DOI

10.1109/4.553171

Filename

553171