Accession Number:

ADA279337

Title:

Use of Allpass Networks to tune the Center Frequency of Sigma Delta Modulators

Descriptive Note:

Professional paper

Corporate Author:

NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA

Personal Author(s):

• Harris, Fred
• Caulfield, Bob
• McKnight, Bill

Report Date:

1993-11-01

Pagination or Media Count:

6.0

Abstract:

Standard sigma-delta modulators use feedback around 1-bit quantizers to transform open loop integrator poles into closed loop transmission zeros of the noise transfer function. The DC transmission zeros permit high resolution quantization of data over a frequency band in their neighborhood. Closed loop zeros can be shifted to arbitrary spectral locations by doubling the number of integrators and then applying local feedback around integrator pairs thereby converting them to resonators. These spectrally shifted zeros support high resolution quantization at the selected arbitrary center frequency. In this paper we describe an alternate technique for shifting the open loop poles around the unit circle. In this method, rather than forming resonators, we use a spectral transformation on the baseband process performed by imbedded all-pass filters. Analog to digital filters, Low-power filter, Digital filter.

Descriptors:

• *TIME
• *FREQUENCY MODULATORS
• FREQUENCY
• LOW POWER
• FUNCTIONS
• REPRINTS
• FEEDBACK
• STANDARDS
• ANALOGS
• INTEGRATORS
• MODULATORS
• LOOPS
• ANALOG TO DIGITAL CONVERTERS
• NUMBERS
• COMPUTER NETWORKS
• TRANSFER
• NOISE
• FILTERS
• RESONATORS
• DELTAS
• CIRCLES
• DIGITAL FILTERS
• DIGITAL TO ANALOG CONVERTERS
• TRANSFORMATIONS
• PAPER
• CLOSED LOOP SYSTEMS
• POWER
• QUANTIZATION
• SHIFTING
• FREQUENCY BANDS
• TRANSFER FUNCTIONS
• RESOLUTION
• HIGH RESOLUTION

Subject Categories:

• Electrical and Electronic Equipment
• Computer Systems
• Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE