Analog-to-digital converter operable with staggered timing

• US 20060097901A1
• Filed: 10/06/2005
• Published: 05/11/2006
• Est. Priority Date: 10/08/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Draxelmayr, Dieter, Vogel, Christian, Kubin, Gernot
• Granted Patent: US 7,501,967 B2
• Time in Patent Office: Days
• US Class Current: 341/155
• CPC Class Codes: H03M 1/1215 using time-division multiplexing

Abstract

An arrangement for a time interleaved analog-to-digital converter that converts an signal to a digital signal and has a converter array with a plurality of analog-to-digital converters arranged in a fixed sequence in parallel with one another and can be operated with staggered timing with respect to one another is disclosed. The arrangement has a connection network which, for the purposes of actuation with staggered timing, generates in each case one control signal for an individual analog-to-digital converter in each case, with the connection network predefining the time sequence with which the control signals actuate the individual analog-to-digital converters in such a way that owing to this sequence of the control signals and thus the sequence of the actuated individual analog-to-digital converters there is at least a reduction in an interference spectrum in the spectrum of the input and/or output signal. A sorting method for operating this analog-to-digital converter is also disclosed.

Claims

1. An analog-to-digital converter arrangement, comprising:

an analog-to-digital converter for converting an input signal (XIN) into a digital output signal, said analog-to-digital converter operating with staggered timing and comprising a converter array having a plurality of individual analog-to-digital converters (15-1 to 15-4) being arranged in a fixed sequence in parallel with one another and operable with staggered timing with respect to one another; and

a connection network configured to generate, for a staggered timing actuation, a control signal for each of said individual analog-to-digital converters (CLK1′

-CLK4′

), said connection network predefining a time sequence with which said control signals (CLK1′

-CLK4′

) actuate said individual analog-to-digital converters in such a way that owing to said sequence and thus the sequence of said actuated individual analog-to-digital converters there is at least a reduction in an interference spectrum in the spectrum of said digital output signal (XIN, XOUT).

2. The converter arrangement of claim 1, wherein said connection network comprises at least a clock input into which at least a clock signal (CLK, CLK1-CLK4) can be input, said connection network generating, from said input clock signals (CLK, CLK1-CLK4), clocked control signals as said control signals, said clock control signals having a predetermined time difference with respect to one another and being used to actuate said individual analog-to-digital converters (15-1 to 15-4).

3. The converter arrangement of claim 1, comprising at least three as said individual analog-to-digital converters each being connected by their signal path to an input of said converter arrangement to pick-up an analogue input signal (XIN) present at said input, sample said picked-up input signal (XIN) and convert the sampled signal input signal (XIN) to digital intermediate signals (Z-1 to Z-4).

4. The converter arrangement of claim 1, comprising at least four as said individual analog-to-digital converters each being connected by their signal path to an input of said converter arrangement to pick-up an analogue input signal (XIN) present at said input, sample said picked-up input signal (XIN) and convert picked-up input signal (XIN) to digital intermediate signals (Z-1 to Z-4).

5. The converter arrangement of claim 1, comprising a filter connected downstream of said converter arrangement, said filter filtering said output signal (XOUT) to filter out an energy from undesired interference spectrums, present in addition to a wanted spectrum, from a spectrum of said output signal (XOUT).

6. The converter arrangement of claim 5, wherein said filter is a low-pass filter.

7. The converter arrangement of claim 1, wherein said connection network comprises a counter being triggered by a central clock signal (CLK) and generating a counter sequence (Z1), and wherein each of said individual analog-to-digital converters comprises connected upstream on the control side at least one actuation circuit which assigns a counter reading of the counter sequence generated by the counter to each individual analog-to-digital converter, in each case as a control signal (CLK1′

-CLK4′

).

8. The converter arrangement of claim 7, wherein said actuation circuit comprises in each case a memory register and a comparator, each of said comparators being configured to compare said counter sequence (Z1) with a register content being stored a respective of said memory registers.

9. The converter arrangement of claim 1, comprising a measuring device having a measuring output, said measuring device determining at least one of the properties of said individual analog-to-digital converters or the parameters which influence said spectrum and providing, at said measuring output, a respective measurement signal.

10. The converter arrangement of claim 9, wherein said measuring device is configured to pick-up at least one of said input signal (XIN) or said output signal and to determine the spectrum of these signals (XIN, XOUT) therefrom for determining the properties of the individual analog-to-digital converters and/or for determining the parameters which influence the spectrum.

11. The converter arrangement of claim 9, where an evaluation device evaluates a measurement signal (M1) of the measuring device and generates, as a function of this evaluation, setting signals (E1) four actuating and setting in an optimum way the connections of the connection network.

12. The converter arrangement of claim 1, wherein said connection network comprises fixed connecting devices.

13. The converter arrangement of claim 1, wherein said connection network comprises variable connection devices which can be varied by means of controllable switches.

14. The converter arrangement of claim 1, comprising a first group of individual analog-to-digital converters is provided in which the sequence of the individual analog-to-digital converters is assigned in accordance with a reduction in an interference spectrum in the spectrum (PS) of the input signal (XTN) and/or output signal (XOUT), and at least a second group of individual analog-to-digital converters is provided in which an assignment of the sequence of the individual analog-to-digital converters is provided according to the randomization method.

15. A sorting method for operating a converter arrangement for spectral shaping of the spectrum of an output signal (XOUT), comprising the steps:

(a) providing a converter array having a plurality of individual analog-to-digital converters are arranged in a fixed sequence and in parallel with one another;

(b) determining at least a parameter for an optimum sequence of the individual analog-to-digital converters within the converter array; and

(c) assigning a sequence of the individual analog-to-digital converters with which they are actuated with staggered timing accordance with the determined parameter or parameters.

16. The method of claim 15, where the determined parameters are derived from the properties of the individual analog-to-digital converters.

17. The method, of claim 15, where the determined parameters are derived from the input signal (XIN) and/or the output signal (XOUT) by determining and evaluating the spectrum (PS) of the output signal (XOUT).

18. The method of claim 15, where the determined parameters are derived from the amplification, the time offset, the sampling time and/or the bandwidth of the individual analog-to-digital converters.

19. The method of claim 15, where a first group and at least a second group of individual analog-to-digital converters are provided, with alternate individual analog-to-digital converters of the first group and of the second group being selected for a determination of an optimized sequence of the individual analog-to-digital converters, and in that the selection of an individual analog-to-digital converter is carried out randomly within a respective group.

20. The method of claim 15, characterized in that a plurality of groups of optimized sequences are made available for the individual analog-to-digital converters of a converter array, with a new group for the successive conversion cycle or cycles being selected randomly after a predetermined number of conversion cycles, in particular after each conversion cycle.

21. The method of claim 15, where at least a first group of individual analog-to-digital converters is provided, with the sequence of the individual analog-to-digital, converters being assigned in accordance with the determined sequence, in accordance with a reduction in an interference spectrum in the spectrum of the input signal (XIN) and/or output signal (XOUT), and at least a second group of individual analog-to-digital converters is provided in which the sequence of the individual analog-to-digital converters is assigned according to the randomization method.