Patent ID: 8581763
Filing Date: 2013-11-12
Classification: H03M

Abstract:
1. A delta-sigma modulator comprising: a plurality of integrators cascaded to an input of an analog signal; a quantizer configured to quantize an output signal of the integrator at a last stage and output a resultant digital signal; a first digital-to-analog converter for feedback configured to convert the digital signal obtained by the quantizer into an analog signal and supply the analog signal to an input side of at least the integrator at a first stage; an adder, arranged at an input stage side of the integrator at the last stage, configured to add an output of the integrator at a preceding stage of the integrator at the last stage to at least one path signal supplied from at least another path via a first resistor having at least a first coefficient, wherein the integrator at the last stage comprises an operational amplifier, an integration capacitor, and a second resistor having a second coefficient, the integration capacitor and the second resistor being connected in series between one input terminal and an output terminal of the operational amplifier, a coefficient of each degree of an open loop transfer function being determined in accordance with the first coefficient of the first resistor and the second coefficient of the second resistor, wherein integrators of at least two stages are cascaded via the resistors to the input side of the integrator at the last stage; a feedforward path for forward feeding an output of at least the integrator at the first stage to the adder at the input side of the integrator at the last stage via the first resistor; a second digital-to-analog converter for feedback configured to convert a digital signal obtained by the quantizer into an analog signal and supply the analog signal to the adder at the input side of the integrator at the last stage; a capacitor configured to couple an output of the second digital-to-analog converter with the integrator at the last stage; and a third resistor connected to the capacitor in series.