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US 6,275,177 B1Granted
Sigma-delta modulator using a local nonlinear feedback loop technique
AssigneeIndustrial Technology Research Institute
InventorsChian C. Ho, Hsun-Chang Hsieh, Chung J. Kuo
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Abstract
A local nonlinear feedback loop (LNFL) technique and a sigma-delta modulator (SDM) for promoting highly stable oversampling using the LNFL technique. Not only can gain mismatch of the sigma-delta modulator be minimized, but the overload of the later stage sigma-delta modulator can also be resolved without sacrificing the signal noise ratios (SNR) of the overall system. Moreover, using the local nonlinear feedback loop technique of this invention attenuates the voltage signal of the sigma-delta modulator, therefore decreasing the power consumption of the overall sigma-delta modulator system.
Claims40
A sigma-delta modulator (SDM) using a local nonlinear feedback loop (LNFL) technique comprising:
- plural modulation units connected in series, for generating plural modulated signals and plural quantized error signals, wherein the input end of at least one of said modulation units is coupled to an analog input signal, and the input ends of other said modulation units are coupled to said quantized error signals, respectively;
- a level adjustment unit selectively arranged at the input end of at least one of said other modulation units for determining whether an addition or subtraction of a specified value will be performed to at least one of said quantized error signals in accordance with a signal value of said at least one of said quantized error signals of at least one of said modulation units, and performing in accordance with said determined result a subtraction or an addition of said specified value from or to a modulated signal of at least one of said modulation units, wherein at least one level adjustment unit is arranged in said SDM;
- and
- an adder-synthesizer unit coupled to the plural modulation signals generated by said plural modulation units for generating an output signal of the SDM.
1 more element
A sigma-delta modulator (SDM) using local nonlinear feedback loop (LNFL) comprising:
- a modulation unit for generating a modulated signal and a quantized error signal, respectively;
- a level adjustment unit for receiving an analog input signal and determining whether an addition or subtraction of a specified value will be performed to said analog input signal in accordance with the magnitude of said analog input signal, thereby limiting the range of said analog input signal, and outputting the obtained result to said modulation unit;
- and
- a synthesizer unit for receiving said modulated signal and a compensation signal to obtain an output signal of the SDM, wherein said compensation signal is outputted by the level adjustment unit when the signal magnitude of said compensative signal equals said specified value.
1 more element
A local nonlinear feedback loop (LNFL) method for use in a sigma-delta modulator (SDM), the method comprising the steps of:
- selectively arranging input-signal adjustment devices in front of respective input ends of various stage integrator modulation units, for controlling a magnitude of an input signal of said various stage integrator modulation units, respectively;
- subtracting a second specified value from said input signal by means of a corresponding input signal adjustment device, then outputting a value obtained from the subtraction to at least one of said various stage integrator modulation units, and further adding said second specified value to the output signal of at least one of said various stage integrator modulation units when the input signal of at least one of said various stage integrator modulation units is greater than a first specified value;
- adding said second specified value to said input signal by means of an input signal adjustment device, then outputting it to at least one of said various stage integrator modulation units, and subtracting said second specified value from an output signal of at least one of said various stage integrator modulation units when the input signal of said coupled integrator modulation units is smaller than said first specified value.
A sigma-delta modulator (SDM) using a local nonlinear feedback loop (LNFL) comprising:
- plural modulation units connected in series S1-Sn, for generating plural modulated signals Y1-Yn and plural quantized error signals −Q1-−Qn, wherein the input end of a modulation unit Sj is coupled to an analog signal X input, and input ends of other said modulation units S2-Sn are coupled to said quantized error signals Q1-−Qn−1, respectively;
- a level adjustment unit Mj selectively arranged at an input end of a modulation unit Sj+1 for selecting a level signal from at least one of level signals 2Vref, Vref, 0, −Vref and coupling the selected level signal to the input end of said modulation unit Sj+1 in accordance with a signal value of a quantized error signal −Qj of a modulation unit Sj, and for subtracting or adding in accordance with the selected level signal a specified value Δ from to a modulated signal Yj+1 of said modulation unit Sj+1, where 1≦j≦n−1 and at least one of said level adjustment units is arranged in said SDM;
- and
- an adder-synthesizer unit coupled to the plural modulation signals Y1-Yn generated by said plural modulation units S1-Sn for generating an output signal Y of the SDM.
1 more element
A sigma-delta modulator (SDM) using a local nonlinear feedback loop (LNFL), comprising:
- a modulation unit, for generating a modulation signal and a quantized error signal, respectively.
- a level adjustment unit, for receiving an analog input signal and for selecting one of voltage signals 2Vref, Vref, 0, and −Vref, in accordance with the magnitudes of said modulation signal and said analog input signal, to couple with the input end of said modulation unit, and for generating a compensation signal in accordance with the selecting result;
- a synthesis operator for receiving said modulation signal and said compensation signal and then obtaining an output signal of the SDM;
- wherein the level adjustment unit outputs said compensation signal, the magnitude of said compensation signal equaling a specific amount Δ or 0.
1 more element
Dependencies are inferred from the claim text.