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Continuous-time Bandpass Delta-Sigma Modulator with Integrator/Itegrators Feedback

IP.com Disclosure Number: IPCOM000014789D
Original Publication Date: 2002-Jul-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Abstract

Continuous-Time Bandpass Delta-Sigma Modulator is a solution for high-speed, high-resolution A/D (Analog to Digital) converters. Most of the techniques for Delta-Sigma Modulator design are discrete, which makes the exact modeling of Continuous Delta-Sigma Modulator difficult. The transform from discrete to continuous

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  Continuous-time Bandpass Delta-Sigma Modulator with Integrator/Itegrators Feedback

Continuous-Time Bandpass Delta-Sigma Modulator is a solution for high-speed, high-resolution A/D (Analog to Digital) converters. Most of the techniques for Delta-Sigma Modulator design are discrete, which makes the exact modeling of Continuous Delta-Sigma Modulator difficult. The transform from discrete to continuous
[1] is not straightforward because of the transfer function of a real resonator [As/(s^2+w^2)]. Because of this some techniques are in use [2], which are not one-to-one compatible with the analog circuit.

     The invention is a new architecture that can be shown to be a continuous impulse-invariant transform of a discrete-time model of Bandpass Delta-Sigma Modulator even when using real resonators (with As/(s^2+w^2) transfer function). The new architecture is also more robust against jitter (does not use the HRZ feedback [2]) and easier to implement. A block diagram of the new architecture is followed:

     The block diagram is of 2N-order Bandpass Delta-Sigma Modulator. It makes use of N real resonators and M integrators. The output of the last resonator (#N) is sampled every T seconds (2-level or multilevel) and converted to analog (can be RZ (Return to Zero) pulse or other). This Converted analog signal is the input to M integrators line. The output of each integrator (with 1/s transfer function) can go to each one of the adders.

References:
[1] "Excess Loop Delay in Continuo...