Using sigma-delta A/D methods, high resolution can be obtained for only low to medium signal bandwidths. This article describes conventional A/D conversion, as well as its performance modeling. We then look at the technique of oversampling, which can be used to improve the resolution of classical A/D methods. We discuss how sigma-delta converters use the technique of noise shaping in addition to oversampling to allow high resolution conversion of relatively low bandwidth signals. We examine the use of sigma-delta converters to convert narrowband bandpass signals with high resolution. Several parallel sigma-delta converters, which offer the potential of extending high resolution conversion to signals with higher bandwidths, are also described.

An overview of sigma-delta converters

The communication system includes a hybrid fiber/coax distribution network. A head end provides for downstream transmission of telephony and control data in a first frequency bandwidth over the hybrid fiber/coax distribution network and reception of upstream telephony and control data in a second frequency bandwidth over the hybrid fiber/coax distribution network. The head end includes a head end multicarrier modem for modulating downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulating upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth. The system includes service units, operatively connected to the hybrid fiber/coax distribution network for upstream transmission of telephony and control data and for receipt of the downstream control data and telephony. Also provided is a method and apparatus for performing a Fast Fourier Transform (FFT).

Communication system with multicarrier telephony transport

A radio frequency power amplifier includes a feedback control system coupled to an input signal and a first feedback signal and configured to provide an output; a controlled supply configured to provide power that is controlled in accordance with a signal; and a radio frequency gain stage powered from the controlled supply, driven by the output from the feedback control system, and configured to provide an output signal at the radio frequency to a resonant load, where the first feedback signal corresponds to the output signal. Some embodiments include a sequencer in the feedback control system and others utilize an additional feedback loop to control the power provided by the controlled supply.

Radio frequency power amplifier and method using a controlled supply

This paper presents a tutorial overview of ΣΔ modulators, their operating principles and architectures, circuit errors and models, design methods, and practical issues. A review of the state of the art on nanometer CMOS implementations is described, giving a survey of cutting-edge ΣΔ architectures, with emphasis on their application to the next generation of wireless telecom systems.

Sigma-Delta Modulators: Tutorial Overview, Design Guide, and State-of-the-Art Survey

All-CMOS radio transceivers and systems-on-a-chip are rapidly making inroads into a wireless market that for years was dominated by bipolar and BiCMOS solutions. It is not a matter of replacing bipolar transistors in known circuit topologies with FETs; the wave of RF CMOS brings with it new architectures and unprecedented levels of integration. What are its origins? What is the commercial impact? How will RF CMOS evolve in the future? This paper offers a retrospective and a perspective.

RF CMOS comes of age

A bandpass version of sigma-delta modulation is presented, with simulation results for second- and fourth-order convertors. For the fourth-order convertor operating at 8 MHz, simulations demonstrate a resolution of 16 bits over an 8 kHz band centred at 1 MHz. Applications may include analogue/digital conversion for AM radio, and digital/analogue conversion for narrowband RF systems.

Bandpass sigma-delta modulation

The traditional low-pass sigma-delta ( Sigma Delta ) analog-to-digital converter is extended to the bandpass case. For input signals with small relative bandwidths, bandpass Sigma Delta converters offer high signal-to-noise ratios at significantly lower sampling rates than are required for low-pass Sigma Delta converters. A sixth-order single-ended switched-capacitor circuit, clocked at 3 MHz, is designed to convert bandpass signals centered at 455 kHz with 20-kHz bandwidth. Time-domain circuit simulations show that this modulator realizes a 94-dB signal-to-noise ratio for a half-scale input, giving roughly 16-b performance. >

Bandpass sigma-delta analog-to-digital conversion

Untether's “Kensington” and “Boqueria” are two generations of architecture for massively parallel and highly efficient inference accelerators. They are reconfigurable at two different granularity scales: a packet scale based on precomputed circuit-switched minimum-distance Cartesian routing and a bytescale local permutation that can be reconfigured under program control. The coarse level naturally models neural-net layers and block matrices, while the permutation level carries that flexibility down to the fine structure of linear-algebra computations.

M. Snelgrove

Papers

Bandpass sigma-delta modulation

Bandpass sigma-delta analog-to-digital conversion

CGRA4HPC 2022 Invited Speaker: Dual-scale reconfigurable arrays for ML Inference