Configurable time-interleaved analog-to-digital converter
A time-interleaved analog-to-digital converter for conversion of L analog input signals to L corresponding digital output signals comprises an array of N (N>L) constituent analog-to-digital converters each having an analog input and a digital output and each adapted to digitize an analog input sample, and a controller adapted to (for each of the L analog input signals indexed by i=1, 2, . . . , L) select a number N i , of constituent analog-to-digital converters from the array of N constituent analog-to-digital converters (wherein N i ≧1 and Σ i=1 L N i ≦N), and cause each sample of the analog input signal to be digitized in a respective one of the selected N i , constituent analog-to-digital converters. The analog-to-digital converter also comprises a multiplexer adapted to (for each of the L analog input signals) multiplex the digitized samples of each of the selected Ni constituent analog-to-digital converters to produce the digital output signal.
1. A method of operating a time-interleaved analog-to-digital converter for conversion of an integer number L of analog input signals to L corresponding digital output signals, wherein L is larger than 1, the analog input signals and digital output signals are indexed by i =1, 2, . . . , L, and the time-interleaved analog-to-digital converter comprises an array of an integer number N of constituent analog-to-digital converters each having an analog input and a digital output, wherein N is larger than L, the method comprising, for each of the L analog input signals:
sampling the analog input signal;
selecting a number N i of constituent analog-to-digital converters from the array of N constituent analog-to-digital converters, wherein N i is larger than or equal to 1 and Σ i=1 L N i ≦N;
digitizing each sample of the analog input signal in a respective one of the selected N i constituent analog-to-digital converters; and
multiplexing the digitized samples of each of the selected N i constituent analog-to-digital converters to produce the digital output signal corresponding to the analog input signal.
2. The method of claim 1 wherein, if N i is larger than 1, digitizing each sample of the analog input signal in a respective one of the selected N i constituent analog-to-digital converters comprises:
digitizing a first sample of the analog input signal in a first selected constituent analog-to-digital converter; and
digitizing a second sample of the analog input signal in a second selected constituent analog-to-digital converter.
3. The method of claim 1 further comprising, for each of the L analog input signals, de-multiplexing the analog input signal into N i de-multiplexed signals, and wherein digitizing each sample of the analog input signal in a respective one of the selected N i constituent analog-to-digital converters comprises processing each of the N i de-multiplexed signals in the respective one of the selected N i constituent analog-to-digital converters.
4. The method of claim 1 wherein each of the L digital output signals has a respective sample rate R i and at least two of the sample rates R i , i =j,k differ from each other such that R j >R k , and wherein selecting, for each of the L analog input signals, the number N i of constituent analog-to-digital converters comprises selecting N i , i =j,k such that
R
j
R
k
≤
N
j
N
k
.
5. The method of claim 1 wherein each of the L digital output signals has a respective sample resolution Q i and at least two of the sample resolutions Q i , i=j,k differ from each other such that Q j >Q k , and wherein selecting, for each of the L analog input signals, the number N i of constituent analog-to-digital converters comprises selecting N i , i=j,k such that
Q
j
Q
k
≤
N
j
N
k
.
6. The method of claim 1 wherein sampling the analog input signal comprises, for at least one of the L analog input signals, sampling the analog input signal at a sample rate which is higher than a sample rate of the digital output signal corresponding to the analog input signal and the method further comprises post-processing the digitized samples of each of the selected N i constituent analog-to-digital converters to produce the digital output signal corresponding to the analog input signal.
7. A computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause execution of the method according to claim 1 when the computer program is run by the data-processing unit.
8. A time-interleaved analog-to-digital converter for conversion of an integer number L of analog input signals to L corresponding digital output signals, wherein L is larger than 1 and the analog input signals and digital output signals are indexed by i=1, 2, . . . , L, the time-interleaved analog-to-digital converter comprising:
an array of an integer number N, wherein N is larger than L, of constituent analog-to-digital converters each having an analog input and a digital output and each adapted to digitize an analog input sample;
a controller adapted to, for each of the L analog input signals:
select a number N i of constituent analog-to-digital converters from the array of N constituent analog-to-digital converters, wherein N i is larger than or equal to 1 and Σ i=1 L N i ≦N; and
cause each sample of the analog input signal to be digitized in a respective one of the selected N i constituent analog-to-digital converters; and
a multiplexer adapted to, for each of the L analog input signals, multiplex the digitized samples of each of the selected N i constituent analog-to-digital converters to produce the digital output signal corresponding to the analog input signal.
9. The time-interleaved analog-to-digital converter of claim 8 further comprising a de-multiplexer adapted to, for each of the L analog input signals, de-multiplex the analog input signal into N i de-multiplexed signals, and wherein the controller is adapted to cause each of the N i de-multiplexed signals to be processed in the respective one of the selected N i constituent analog-to-digital converters.
10. The time-interleaved analog-to-digital converter of claim 9 further comprising a sample-and-hold unit for each of the L analog input signals, adapted to provide analog input samples to the de-multiplexer.
11. The time-interleaved analog-to-digital converter of claim 8 further comprising a sample-and-hold unit for each of the N constituent analog-to-digital converters, adapted to provide analog input samples to the N constituent analog-to-digital converters.
12. The time-interleaved analog-to-digital converter of claim 8 wherein each of the L digital output signals has a respective sample rate R i and at least two of the sample rates R i ,i=j,k differ from each other such that R j >R k , and wherein the controller is adapted to select, for each of the L analog input signals, the number N i =j,k of constituent analog-to-digital converters such that
R
j
R
k
≤
N
j
N
k
.
13. The time-interleaved analog-to-digital converter of claim 8 wherein each of the L digital output signals has a respective sample resolution Q i and at least two of the sample resolutions Q i , i=j,k differ from each other such that Q j >Q k , and wherein the controller is adapted to select, for each of the L analog input signals, the number N i , i=j,k of constituent analog-to-digital converters such that
Q
j
Q
k
≤
N
j
N
k
.
14. An integrated circuit comprising the time-interleaved analog-to-digital converter of claim 8 .
15. An electronic device comprising the integrated circuit of claim 14 .
16. An electronic device comprising the time-interleaved analog-to-digital converter of claim 8 .