ΔΣ modulation circuit and system
A ΔΣ modulation circuit that includes a first integrator and second integrator coupled in series, a quantizer coupled to an output of the second integrator, a delay device disposed in a feedback path from an output of the quantizer to an input of the first and second integrators, an adder which generates a difference between an output and an input of the quantizer, and a feedback circuit including a delay device which couples an output of the adder to an output of one of the first and second integrators.
1. A ΔΣ modulation circuit, comprising:
a first integrator and second integrator coupled in series;
a quantizer coupled to an output of the second integrator;
a delay device disposed in a feedback path from an output of the quantizer to an input of the first and second integrators;
an adder configured to generate a difference between an output and an input of the quantizer; and
a feedback circuit including a delay device configured to couple an output of the adder to an output of one of the first integrator and the second integrator,
wherein the output of the adder is coupled to the output of the second integrator, and the feedback circuit includes only the delay device.
2. A ΔΣ modulation circuit, comprising:
a plurality of ΔΣ modulators, each of which includes integrators and quantizers coupled in series, and delay devices disposed in feedback paths from an output of the quantizers to an input of the integrators and outputs a difference between an output and an input of a quantizer at a ΔΣ modulator previous stage to an input of a subsequent ΔΣ modulator stage;
an adder which adds the outputs of the ΔΣ modulators; and
at least one differentiator disposed between an output of the ΔΣ modulator of each of a second stage and subsequent stages and the adder,
wherein at least one of the ΔΣ modulators includes a feedback circuit including a delay device for feeding the difference back to an output of the at least one of the ΔΣ modulator.
3. The ΔΣ modulation circuit according to claim 2 , wherein the feedback circuit includes only the delay device.
4. A system, comprising:
a quadrature modulator configured to quadrature-convert an analog signal and generates an output signal; and
a synthesizer configured to generate a clock CK for a modulation of the quadrature modulator and includes a ΔΣ modulation circuit; and
wherein the ΔΣ modulation circuit includes:
a first integrator and second integrator coupled in series;
a quantizer coupled to an output of the second integrator;
a delay device disposed in a feedback path from an output of the quantizer to an input of the first and second integrators;
an adder configured to generate a difference between an output and an input of the quantizer; and
a feedback circuit including a delay device configured to couple an output of the adder to an output of one of the first integrator and the second integrator.
5. The system according to claim 4 , wherein the output of the adder is coupled to the output of the first integrator, and the feedback circuit includes the delay device and a differentiator coupled in series.
6. The system according to claim 4 , wherein the output of the adder is coupled to the output of the second integrator, and the feedback circuit includes only the delay device.