Quantizer in a multilevel sigma-delta analogue/digital converter
View Patent ↗The quantizer ( 2 ′) has an input network ( 5 ) which generates N different drive signals (V ij ) as a function of the quantizer input signal (V I+ −V I− ). The input network ( 5 ) is designed in such a way that a value of the respective drive signal (V ij ) which is greater than a comparison value indicates that the quantization threshold which is associated with the respective drive signal (V ij ) has been exceeded. Furthermore, the quantizer has a switching network ( 9 ), which associates the N drive signals (V ij ) with the N comparator inputs.
1. A quantizer having a plurality of N quantization thresholds for quantization of an analogue quantizer input signal for a sigma-delta analogue/digital converter, comprising
an input network, which receives the quantizer input signal and generates N different drive signals, which are associated with the quantization thresholds, as a function of the quantizer input signal, in which case, for the drive signals, a value of the respective drive signal which is greater, or alternatively less, than a comparison value which is identical for all drive signals indicates that the quantizer input signal has exceeded the respectively associated quantization threshold,
a plurality of N comparators each having one comparator input, and which, on the output side, generate a quantized signal which corresponds to the quantizer input signal, and
a switching network, which receives the N drive signals and associates them with the N comparator inputs, in which case the association can be controlled as a function of a control signal.
2. A quantizer according to claim 1 , wherein
N − of the N drive signals each have a value less than the comparison value and N + of the N drive signals each have a value greater than the comparison value, and both the number N − and the number N + of the drive signals are dependent on the quantizer input signal.
3. A quantizer according to claim 1 , wherein
the quantizer input signal and the drive signals are differential signals, in particular with the comparison value being 0 V.
4. A quantizer according to claim 1 , wherein
the input network comprises a resistor chain of N resistors with identical resistances, in particular N identical resistors, with the N drive signals being obtained from the potentials at the nodes of the resistors.
5. A quantizer according to claim 3 , wherein
the differential quantizer input signal is received by both outer nodes of the resistor chain.
6. A quantizer according to claim 5 , wherein
the input network comprises N−1 current sources with identical currents, in particular N−1 identical current sources, with each node between two resistors in the resistor chain being fed from in each case one of the current sources.
7. A quantizer according to claim 6 , wherein
the N drive signals are each obtained from the difference between the potentials at the two nodes of a respectively different resistor of the N resistors.
8. A quantizer according to claim 6 , wherein
the following relationship applies to the potentials of the nodes of the N resistors:
V
i
=
(
N
+
1
-
i
)
N
·
V
1
+
(
i
-
1
)
N
·
V
N
+
1
+
(
i
-
1
)
(
N
+
1
-
i
)
2
·
RI
0
,
where the variable V i describes the potential at the i-th node in the resistor chain, the variable R describes the resistance of a resistor in the resistor chain, and the variable I 0 describes the current from one of the current sources.
9. A quantizer according to claim 6 , wherein
the product of the current from one of the current sources and the resistance of a resistor in the resistor chain is proportional to the width of the permissible voltage value range of the quantizer input signal.
10. A sigma-delta analogue/digital converter, comprising a quantizer according to claim 1 , further comprising:
a control device for generation of the control signal, with the association of the N drive signals with the N comparator inputs being controlled via the control signal.
11. A method of quantization of an analogue quantizer input signal for a sigma-delta analogue/digital converter, comprising the steps of:
receiving the quantizer input signal
generating N different drive signals which are associated with the quantization thresholds as a function of the quantizer input signal wherein for the drive signals a value of the respective drive signal which is greater than a comparison value which is identical for all drive signals indicates that the quantizer input signal has exceeded an associated quantization threshold,
associating the drive signals with comparator inputs of N comparators, wherein the association can be controlled as a function of a control signal, and
generating a quantized signal which corresponds to the quantizer input signal by the N comparators.
12. A method according to claim 11 , wherein
N − of the N drive signals each have a value less than the comparison value and N + of the N drive signals each have a value greater than the comparison value, and both the number N − and the number N + of the drive signals are dependent on the quantizer input signal.
13. A method according to claim 11 , wherein
the quantizer input signal and the drive signals are differential signals, in particular with the comparison value being 0 V.
14. A method of quantization of an analogue quantizer input signal for a sigma-delta analogue/digital converter, comprising the steps of:
receiving the quantizer input signal
generating N different drive signals which are associated with the quantization thresholds as a function of the quantizer input signal wherein for the drive signals a value of the respective drive signal which is less than a comparison value which is identical for all drive signals indicates that the quantizer input signal has exceeded an associated quantization threshold,
associating the drive signals with comparator inputs of N comparators, wherein the association can be controlled as a function of a control signal, and
generating a quantized signal which corresponds to the quantizer input signal by the N comparators.
15. A method according to claim 14 , wherein N − of the N drive signals each have a value less than the comparison value and N + of the N drive signals each have a value greater than the comparison value, and both the number N − and the number N + of the drive signals are dependent on the quantizer input signal.
16. A method according to claim 14 , wherein
the quantizer input signal and the drive signals are differential signals, in particular with the comparison value being 0 V.