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Patent 7903011 Click For Printable Version of This Patent
Patent Information:  USPTO Site Listing

Patent Number: 7903011
Case ID: 0
Patent Title: Differential current-mode translator in a sigma-delta digital-to-analog converter
Status: ACTIVE
Status Date: 8/2/2011 3:04:44 PM
Issue Date: 3/8/2011
Filed Date: 9/12/2007
Serial #: 1/898,533
Assignee Name: Honeywell International Inc. (Morristown, NJ)
Inventor(s): Werking, Paul M.
Lab Information:  View Lab Profile

Lab Name: U.S. Army Armament Research, Development and Engineering Center
Location: RDAR-EIB
Picatinny Arsenal, NJ 07806-5000
Contact: Contact Lab About This Patent
   
Description:
FIELD

The present invention relates to sigma-delta digital-to-analog converters, and more specifically, to a differential current-mode translator in a sigma-delta digital-to-analog converter.

BACKGROUND

Sigma-delta digital-to-analog converters (SD DACs) are often used in mixed signal integrated circuits (ICs) that combine digital and analog circuits on the same substrate. Generally, SD DACs consist of a two-state voltage translator followed by a low-pass filter (LPF). The voltage accuracy of the overall SD DAC is generally determined by the input voltage translator.

FIG. 1 is a circuit diagram of an example of a typical SD DAC 100. SD DAC 100 includes a voltage translator stage 102 coupled with a low pass filter 104. The voltage translator stage 102 provides a replica of an input digital signal (DIN) 106 that switches between two relatively stable and accurate voltage references, V.sub.P and V.sub.N. It is possible to use a simple 1-to-1 translat . . . . More
Abstract:
A differential current-mode sigma-delta digital-to-analog converter (SD DAC) and a method for generating positive and negative reference voltages in a sigma-delta digital analog converter are described. The SD DAC includes a low pass filter (LPF) having a first and second input. The SD DAC further includes a first resistance and a second resistance coupled together at a common node. The first resistance may be coupled to the first input of the LPF and the second resistance may be coupled to the second input of the LPF. Additionally, the SD DAC includes a current supply and a switching network for supplying current from the current supply to the first and second resistances. The current supply and the resistances operate to generate a first voltage and a second voltage at the first and second inputs of the LPF.
Claims:
I claim:

1. A sigma-delta digital-to-analog converter (SD DAC) comprising: a low pass filter comprising first and second inputs; first and second resistances each having first and second terminals, wherein the first terminals of the first and second resistances are respectively coupled to the first and second inputs of the low pass filter, and wherein the second terminals of the first and second resistances are respectively coupled together at a common node; a current supply; and a switching network for supplying current from the current supply to the first and second resistances, wherein the current supply and the first and second resistances operate to generate a first voltage and a second voltage at the first and second inputs of the low pass filter, wherein the current supply comprises: a first operational amplifier and a second operational amplifier; a first and second p-type transistor, wherein the first and second p-type transistors are coupled, and wherein the firs . . . . More