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Delta-sigma modulator

A modulator and digital-to-analog converter technology, applied in the field of ΔΣ modulators, can solve problems such as deterioration, inability to quantify noise filtering, and inability to sufficiently suppress noise characteristics.

Inactive Publication Date: 2015-06-17
RENESAS ELECTRONICS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this configuration cannot filter the quantization noise fed back from the output of the quantizer to the input of the integrator
For this reason, this configuration cannot adequately suppress the degradation of noise characteristics caused when out-of-band quantization noise folds back into the frequency band of interest

Method used

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Examples

Experimental program
Comparison scheme
Effect test

no. 1 example

[0042] figure 1 An exemplary configuration of the ΔΣ modulator 1 according to this embodiment is shown. exist figure 1 In the exemplary configuration shown, the ΔΣ modulator 1 includes an integrator 105, a quantizer 107, and a feedback path 114 for providing the output signal of the quantizer 107 to the input of the integrator 105, and the ΔΣ modulator 1 is configured into performing first-order ΔΣ modulation. The ΔΣ modulator 1 is also configured to feed back to the input of the integrator 105 a differential error signal 112 representing the derivative of the quantization error (or quantization noise) q caused by the quantizer 107 . Thereafter, the figure 1 The configuration and operation of the shown ΔΣ modulator 1 are described in detail.

[0043] Integrator 105 includes an integrating stage and integrates the signal provided by adder 104 . Adder 104 subtracts the feedback signal provided by feedback path 114 from signal 103 . Signal 103 is produced by amplificatio...

no. 2 example

[0055] In this embodiment, a modification of the ΔΣ modulator 1 according to the first embodiment will be described. image 3 An exemplary configuration of the ΔΣ modulator 2 according to the present embodiment is shown. ΔΣ modulator 2 has essentially the same figure 1 and 2 The same configuration is shown for ΔΣ modulator 1. The difference therebetween is that the ΔΣ modulator 2 comprises a smoothing block 213 for smoothing the differential error signal 212 produced by the differential block 211 and is configured to combine the smoothed differential error signal 214 and the output signal 208 of the quantizer 207 (Y ) is fed back to the input of integrator 205. Thereafter, the image 3 The configuration and operation of the shown ΔΣ modulator 2 are described in detail.

[0056] The amplification block 202 amplifies the amplitude of the input signal 201 (X) of the ΔΣ modulator 2 . exist image 3 In the example of , it is assumed that the amplification block 202 is a fou...

no. 3 example

[0070] In this embodiment, a ΔΣ DAC equipped with a ΔΣ modulator according to the first or second embodiment will be described. Figure 5 An exemplary configuration of the ΔΣDAC3 according to the present embodiment is shown. exist Figure 5 In an exemplary configuration of , the ΔΣDAC3 includes a digital interpolation filter 301 , a ΔΣ modulator 302 , a 1-bit DAC 303 , and an analog low-pass filter (LPF) 304 . For example, the digital interpolation filter 301 oversamples an N-bit digital signal with an information rate fs to generate an N-bit digital signal with an information rate fosr=K*fs. As used herein, K represents the oversampling ratio. The number of bits (M bits) of the interpolated (oversampled) digital signal passing through the digital interpolation filter 301 may be equal to or greater than the number of bits (N bits) of the digital signal before oversampling (that is, M=N or M>N) . On the contrary, for example, if accuracy is not important, the number of bits...

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Abstract

A delta-sigma modulator is configured to feedback an output signal of a quantizer to an input of an integrator, and also feedback to the input of the integrator a differentiated error signal representing derivative of quantization error caused by the quantizer.

Description

technical field [0001] This application is based on and claims priority from Japanese Patent Application No. 2013-259876 filed on December 17, 2013, the disclosure of which is hereby incorporated by reference in its entirety. Background technique [0002] ΔΣ modulators are widely used in analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). In this specification, an ADC using ΔΣ modulation and a DAC using ΔΣ modulation are referred to as ΔΣADC and ΔΣDAC, respectively. A ΔΣ modulator may be referred to as a ΣΔ modulator. The ΔΣ modulator can spread the quantization error (or quantization noise) power to the oversampling frequency fosr by oversampling. The delta-sigma modulator can also shift the quantization noise into the higher frequency domain due to its noise-shaping properties, thereby suppressing the quantization noise in the band of interest (typically, the band lower than the Nyquist frequency) . [0003] However, continuous-time ΔΣ modulato...

Claims

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Application Information

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IPC IPC(8): H03M3/00
CPCH03M3/372H03M3/422H03M3/438H03M3/464
Inventor 奥田孝
Owner RENESAS ELECTRONICS CORP