Analog to digital converter system

• US 4,222,110 A
• Filed: 09/07/1978
• Issued: 09/09/1980
• Est. Priority Date: 09/07/1978
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Judell, Neil H. K.
• Primary Examiner(s): Smith, Jerry
• Application Number:
  US05/940,249
• Time in Patent Office: 733 Days
• Field of Search: 364/724, 325/42, 340/347 M, 333/18
• US Class Current: 708/319
• CPC Class Codes: H03M 1/0629 Anti-aliasing
• CPC Class Codes: H03M 1/0631 Smoothing

Abstract

Analog to digital conversion is achieved with a reduction in digitization noise and anti-aliasing by coupling an integrating A/D converter to a digital filter having more than two sections and a gain greater than two.

Claims

1. A system for digitizing an analog signal in such manner as to increase the signal to noise ratio and reduce aliasing, comprising

a continuously integrating A/D converter, and

a digital filter coupled to the output of said converter, said digital filter having more than two sections and a gain greater than two.

2. A system as set forth in claim 1 wherein the digital filter 1,2,4,7,11,14,16,18,16,14,11,7,4,2,1 is used.

3. A system as set forth in claim 1 wherein the digital filter 1,3,5,8,10,10,10,8,5,3,1 is used.

4. A system for digitizing an analog signal in such manner as to improve the signal to noise relationship and reduce interference from aliasing, comprising

a continuously integrating A/D converter for providing at its output digitized samples of an analog signal applied to its input, and

a digital filter having an input coupled to the output of said converter, said digital filter having means for making more than two successive digitized samples simultaneously available, means for multiplying each sample and means for adding the outputs of said latter means, the sum of the multiplication being greater than two.

5. A system as set forth in claim 4 wherein the said means for multiplying the digitized samples provides multiplications of 1,2,4,7,11,14,16,18,16,14,11,7,4,2 and 1 in order from the latest sample to the oldest, respectively.

6. A system as set forth in claim 4 wherein the said means for multiplying the digitized samples provides multiplications of 1,3,5,8,10,10,10,8,5,3,1 in order from the latest sample to the oldest, respectively.