Behavior of a 1-bit 2nd-order ΔΣ-modulator under wideband excitation

Author

Lindfors, Saska

Author_Institution

Radioelectron. Lab., R. Inst. of Technol., Kista, Sweden

Volume

1

fYear

2001

fDate

6-9 May 2001

Firstpage

380

Abstract

The internal signal swings of a 1-bit 2^nd-order ΔΣ-modulator were found in simulations to increase uncontrollably as the frequency of a sinusoidal excitation exceeded a certain boundary. This is highly undesirable in radio receivers utilizing digital channel selection as the unfiltered input will contain strong high frequency components. The simulated behavior is confirmed by experimental results from an integrated prototype which suffers from a rapid loss of SNR above the same boundary frequency. The frequency dependent behavior is explained by the correlation between the input signal and the impulse response of the 1-bit ΔΣ-modulator´s loop filter. Simulations indicate that reducing the gain coefficient of the first integrator or alternatively employing multibit quantization eliminates the problem

Keywords

delta-sigma modulation; 1 bit; digital channel selection; gain coefficient; impulse response; integrator; internal signal swing; loop filter; multibit quantization; radio receiver; second-order delta-sigma modulator; signal-to-noise ratio; wideband sinusoidal excitation; Bandwidth; Delta modulation; Digital filters; Filtering; Frequency; Quantization; RF signals; Receivers; Signal resolution; Wideband;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 2001. ISCAS 2001. The 2001 IEEE International Symposium on

Conference_Location

Sydney, NSW

Print_ISBN

0-7803-6685-9

Type

conf

DOI

10.1109/ISCAS.2001.921872

Filename

921872