Signal modulation circuit
AssigneeOnkyo Corporation
InventorsYoshinori Nakanishi, Tsuyoshi Kawaguchi, Mamoru Sekiya
Life of this patent
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Abstract
Provided is a modulation circuit that can correct an output state in real time and reliably modulate an input signal to output the modulated signal. The signal modulation circuit includes a subtracter, an integrator, a chopper circuit, a frequency divider, and a D-type flip-flop. A delay circuit of a sigma delta modulation circuit is not provided to a feedback circuit, and a signal is delayed and quantized in the D-type flip-flop. The chopper circuit inserts a zero level at timing synchronized with a clock signal, so that pulse density modulation is performed.
Claims7
A signal modulation circuit for performing delta sigma modulation on an input signal in synchronization with a clock signal to output the modulated signal, the circuit comprising:
- a subtracter for calculating a difference between the input signal and a feedback signal;
- an integrator for integrating an output signal from the subtracter;
- a phase inverting circuit for inverting a phase of the signal integrated by the integrator;
- a first bias voltage applying circuit for applying a bias voltage to the signal integrated by the integrator;
- a second bias voltage applying circuit for applying a bias voltage to the signal whose phase is inverted by the phase inverting circuit;
- a first zero level inserting circuit for inserting a zero level into the signal output from the first bias voltage applying circuit at timing synchronized with the clock signal;
- a second zero level inserting circuit for inserting a zero level into the signal output from the second bias voltage applying circuit at timing synchronized with the clock signal;
- a first quantizer for delaying the signal output from the first zero level inserting circuit and quantizing the delayed signal;
- a second quantizer for delaying the signal output from the second zero level inserting circuit and quantizing the delayed signal;
- a pulse synthesizing circuit for synthesizing the signal output from the first quantizer with the signal output from the second quantizer;
- and
- a feedback circuit for feeding back the signal synthesized by the pulse synthesizing circuit to the input signal.
Dependencies are inferred from the claim text.