Single loop feed-forward modulator with summing flash quantizer and multi-bit feedback
View Patent ↗A sigma-delta modulator includes a summing junction that receives an input signal. A plurality of integrators are arranged in series, the integrators output an integrated signal value to a multi-input quantizer. The multi-input quantizer has a plurality of comparators each with switched capacitor inputs. The multi-input quantizer outputs a quantized signal to a multi-bit feedback DAC that drives the summing junction.
1. A sigma-delta modulator comprising:
a summing junction receiving an input signal;
a plurality of integrators in series, the integrators outputting an integrated signal value to a multi-input quantizer; and
wherein the multi-input quantizer has a plurality of comparators each with switched capacitor inputs, and
wherein the multi-input quantizer outputs a quantized signal to a multi-bit feedback DAC whose output drives the summing junction and, wherein each comparator implements a function Y=A 1 *S 1 +A 2 *S 2 +A 3 *S 3 +A 4 *S 4 +, . . . where Y is the output of the comparator, A 1 , A 2 , A 3 . . . are constants, and S 1 , S 2 , S 3 . . . are input voltages.
2. The sigma-delta modulator of claim 1 , wherein the sigma-delta modulator is a feed-forward modulator.
3. The sigma-delta modulator of claim 1 , wherein the quantized signal is a multi-level quantized signal.
4. The sigma-delta modulator of claim 1 , wherein each comparator of the plurality of comparators included in the multi-input quantizer comprises:
a first input and a second input, and an output;
a first plurality of capacitors connected to the first input acting as a summing junction, wherein each capacitor of the first plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage; and
a second plurality of capacitors connected to the second input acting as a summing junction, wherein each capacitor of the second plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage.
5. The sigma-delta modulator of claim 1 , wherein the multi-input quantizer outputs the quantized signal to a single multi-bit feedback DAC.
6. The sigma-delta modulator of claim 1 , wherein each comparator of the plurality of comparators included in the multi-input quantizer comprises:
a first plurality of inputs and a second plurality of inputs, and an output;
a first plurality of capacitors connected between the first plurality of inputs and a first summing junction, wherein each capacitor of the first plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage; and
a second plurality of capacitors connected between the second plurality of inputs and a second summing junction, wherein each capacitor of the second plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage.
7. A multi-input comparator comprising:
a first plurality of inputs and a second plurality of inputs, and an output;
a first plurality of capacitors connected between the first plurality of inputs and a first summing junction, wherein each capacitor of the first plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage; and
a second plurality of capacitors connected between the second plurality of inputs and a second summing junction, wherein each capacitor of the second plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage and, wherein the comparator implements a function Y=A 1 *S 1 +A 2 *S 2 +A 3 *S 3 +A 4 *S 4 + . . . , where Y is the output of the comparator, A 1 , A 2 , A 3 . . . are constants, and S 1 , S 2 , S 3 . . . are input voltages.
8. The comparator of claim 7 , wherein the comparator comprises a preamplifier connected to the first and second inputs, followed by a latch, such that the preamplifier includes a high gain amplifier.
9. The comparator of claim 7 , wherein the comparator is included in a multi-input quantizer, wherein the quantizer outputs a multi-level quantized signal.
10. A multi-input comparator comprising:
a first input and a second input, and an output;
a first plurality of capacitors connected to the first input, wherein each capacitor of the first plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage; and
a second plurality of capacitors connected to the second input, wherein each capacitor of the second plurality of capacitors is connected through a switch to one of a corresponding reference voltage and a corresponding input voltage,
wherein the comparator implements a function
Y=A 1 *S 1 +A 2 *S 2 +A 3 *S 3 +A 4 *S 4 + . . .
where Y is the output of the comparator, A 1 , A 2 , A 3 . . . are constants and S 1 , S 2 , S 3 . . . are the input voltages.
11. The comparator of claim 10 , wherein the comparator is included in a multi-input quantizer, wherein the quantizer outputs a multi-level quantized signal.
12. A sigma-delta modulator comprising:
a summing junction receiving an input signal;
a plurality of integrators in series, the integrators outputting an integrated signal value to a multi-input quantizer; and
wherein the multi-input quantizer has a plurality of comparators each with resistor inputs, and
wherein the multi-input quantizer outputs a quantized signal to a multi-bit feedback DAC whose output drives the summing junction and, wherein each comparator implements a function Y=A 1 *S 1 +A 2 *S 2 +A 3 *S 3 +A 4 *S 4 +, . . . where Y is the output of the comparator, A 1 , A 2 , A 3 . . . are constants, and S 1 , S 2 , S 3 . . . are input voltages.
13. The sigma-delta modulator of claim 12 , wherein the sigma-delta modulator is a feed-forward modulator.
14. The sigma-delta modulator of claim 12 , wherein the quantized signal is a multi-level quantized signal.
15. The sigma-delta modulator of claim 12 , wherein each comparator of the plurality of comparators included in the multi-input quantizer comprises:
a first input and a second input, and an output;
a first plurality of resistors connected to the first input acting as a summing junction, wherein each resistor of the first plurality of resistors is connected to one of a corresponding reference voltage and a corresponding input voltage; and
a second plurality of resistors connected to the second input acting as a summing junction, wherein each resistor of the second plurality of resistors is connected to one of a corresponding reference voltage and a corresponding input voltage.
16. The sigma-delta modulator of claim 12 , wherein each comparator of the plurality of comparators included in the multi-input quantizer comprises:
a first plurality of inputs and a second plurality of inputs, and an output;
a first plurality of resistors connected between the first plurality of inputs and a first summing junction, wherein each resistor of the first plurality of resistors is connected to one of a corresponding reference voltage and a corresponding input voltage; and
a second plurality of resistors connected between the second plurality of inputs and a second summing junction, wherein each resistor of the second plurality of resistors is connected to one of a corresponding reference voltage and a corresponding input voltage.