Two stage A/D converter utilizing dual multiplexed converters with a common converter

• US 5,138,319 A
• Filed: 08/20/1991
• Issued: 08/11/1992
• Est. Priority Date: 08/30/1990
• Status: Expired due to Term

• Current Assignee: Intersil Corporation (Renesas Electronics Corporation)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Tesch, Bruce J.
• Primary Examiner(s): Williams, Howard L.
• Application Number:
  US07/750,752
• Time in Patent Office: 357 Days
• Field of Search: 341/141, 341/156, 341/145, 341/161, 341/162, 341/163, 341/146, 341/172, 341/150
• US Class Current: 341/156
• CPC Class Codes: H03M 1/1215 using time-division multiplexing
• CPC Class Codes: H03M 1/145 the steps being performed sequentially in series-connected stages H03M1/141, H03M1/143, H03M1/16 take precedence
• CPC Class Codes: H03M 1/468 in which the input S/H circuit is merged with the feedback DAC array

Abstract

A converter including an even and an odd digital-to-analog converter for converting digital signals from a successive approximation circuit and controlling the odd and even converters and the analog-to-digital converter device to alternate conversion by the even and odd converters. The odd and even converters operate in oppostie phases such that while one is in an acquisition phase the other is in a conversion phase. Each of the odd and even converters includes a separate coarse digital-to-analog converter and a common fine digital-to-analog converter. The control circuit resets the fine digital-to-analog converter during an initial portion of the conversion phase of each of the coarse digital-to-analog converters. In a two stage flash converter, the first stage includes a single analog-to-digital converter and the second stage includes a single digital-to-analog converter and alternatingly operating even and odd analog-to-digital converters.

Claims

1. An analog-to-digital converter comprising:

input means for receiving analog input signals;

successive approximation means for providing successive digital signals approximating an input analog signal;

even converter means including a coarse digital-to-analog converter for converting said successive digital signals to an even analog signal;

odd converter means including a coarse digital-to-analog converter for converting said successive digital signals to an odd analog signal;

a fine digital-to-analog converter shared by said even and odd converter means;

comparator means for comparing said even and odd analog signals to said analog input signal and providing the results to said successive approximation means;

output means for providing a digital output signal; and

control means for controlling said successive approximation means and said even and odd converter means to alternate conversion by said even and odd converter means.

2. An analog-to-digital converter according to claim 1, wherein said even and odd converter means each include an acquisition phase and a conversion phase, and said control means controls said even and odd converter means to be in opposite phases.

3. An analog-to-digital converter according to claim 2, wherein said even and odd converter means each include a capacitive array.

4. An analog-to-digital converter according to claim 2, wherein said even and odd converter means each include a switched capacitor, redistribution array.

5. An analog-to-digital converter according to claim 2, wherein said comparator means includes an even comparator means for comparing said even analog signal to said analog input signal and an odd comparator means for comprising said odd analog signal to said analog input signal.

6. An analog-to-digital converter according to claim 5, wherein said control means initiates resetting the comparator of said even converter means simultaneous with the initiation of a conversion phase of said odd converter means and terminates the resetting of the comparator of said even converter means before the termination of the conversion phase of said odd converter means.

7. An analog-to-digital converter according to claim 1, wherein said control means resets said fine digital-to-analog converter during the initial portion of the conversion phase of each of said coarse digital-to-analog converter.

8. An analog-to-digital converter according to claim 1, wherein said comparator means includes an even comparator means for comparing said even analog signal to said analog input signal and an odd comparator means for comparing said odd analog signal to said analog input signal.

9. An analog-to-digital converter according to claim 8, wherein said control means initiates resetting the comparator of said even converter means simultaneous with the initiation of a conversion phase of said odd converter means and terminates the resetting of the comparator of said even converter means before the termination of the conversion phase of said odd converter means.

10. An analog-to-digital converter according to claim 9, wherein said control means resets said fine digital-to-analog converter during the initial portion of a conversion phase of each of said coarse digital-to-analog converters.

11. An analog-to-digital converter according to claim 10, wherein said control means initiates an acquisition phase of one of the converter means simultaneous with the initiation of a conversion phase of the other converter means and terminates the acquisition phase. of the one converter means before the termination of the conversion phase of the other converter means.

12. An analog-to-digital converter comprising:

input means for receiving analog input signals;

analog-to-digital flash converter means including a resistor array for providing digital signals approximating an input analog signal;

reference means for generating from said approximating digital signals a pair of reference analog signals;

even flash converter means including a capacitor arrays for converting said analog input signals to even digital signals using said pair of reference analog signals;

odd flash converter means including a capacitor arrays for converting said analog input signals to odd digital signals using said pair of reference analog signals;

output means for providing a digital output signal as a combination of said approximating digital signals and either said even or odd digital signals; and

control means for controlling said analog-to-digital flash converter means, said reference means and said even and odd flash converter means to alternate conversion by said even and odd flash converter means.

13. An analog-to-digital converter according to claim 12, wherein said analog-to-digital flash converter means includes a resistor array and said reference means includes an analog multiplexer connected to said resistor array for selecting said pair of reference analog values from said resistor array as a function of said approximating digital signals.

14. An analog-to-digital converter comprising:

input means for receiving analog input signals;

analog-to-digital means for providing digital signals approximating an input analog signal;

even converter means including an even coarse digital-to-analog converter for converting said digital signals to an even analog signal;

odd converter means including an odd coarse digital-to-analog converter for converting said digital signals to an odd analog signal;

a fine digital-to-analog converter shared by said odd and even converter means;

comparator means for comparing said even and odd analog signals to said analog input signal and providing the results to said analog-to-digital means;

output means for providing a digital output signal; and

control means for controlling said analog-to-digital means and said even and odd converter means to alternate conversion by said even and odd converter means.

15. An analog-to-digital converter according to claim 14, wherein said comparator means includes an even comparator means for comparing said even analog signal to said analog input signal and an odd comparator means for comparing said odd analog signal to said analog input signal.

16. An analog-to-digital converter according to claim 15, wherein said control means initiates resetting the comparator of said even converter means simultaneously with the initiation of a conversion phase of said odd converter means and terminates the resetting of the comparator of said even converter means before the termination of the conversion phase of said odd converter means.

17. An analog-to-digital converter according to claim 15, wherein said control means resets said fine digital-to-analog converter during the initial portion of a conversion phase of each of said coarse digital-to-analog converters.

18. A method of converting an analog input signal to a digital output signal comprising the steps of:

converting an analog input signal to digital signals approximating said input analog signal;

converting said digital signals to an even analog signal using an even converter including a coarse digital-to-analog converter;

alternately converting digital signals to an odd analog signal using an odd converter including a coarse digital-to-analog converter;

using a common fine digital-to-analog converter with said even and odd converter; and

comparing said even and odd analog signals to said analog input signal and using the results in the first mentioned step to produce said digital output signal.

19. A method according to claim 18 including initiating resetting a comparator for said even converter simultaneous with the initiation of a conversion phase of said odd converter and terminating the resetting of a comparator for said even converter before the termination of the conversion phase of said odd converter.

20. A method according to claim 18, including resetting said fine digital-to-analog converter during the initial portion of the conversion phase of each of said coarse digital-to-analog converters.

21. A method according to claim 18, including initiating an acquisition phase of one of the even and odd converters simultaneous with the initiation of a conversion phase of the other even and odd converters and terminating the acquisition phase of the one even and odd converters before the termination of the conversion phase of the other even and odd converters.

22. A method according to claim 18, wherein said first mentioned step is performed by a successive approximation analog-to-digital converter.

23. A method of converting an analog input signal to a digital output signal comprising the steps of:

converting an analog input signal to digital signals approximating said input analog signal using a flash converter including a resistor array;

generating from said approximating digital signals a pair of reference analog signals;

converting said analog input signals to even digital signals using said pair of reference analog signals and an even flash converter including capacitor arrays;

alternately converting said analog input signals to odd digital signals using said pair of reference analog signals and odd flash converter including capacitor arrays; and

providing a digital output signal as a combination of said approximating digital signals and either said even or odd digital signals.