摘要:
A digital signal processing system includes a delta sigma modulator that maintains a low pass output during quantizer overload prevention conditions. In at least one embodiment, the delta sigma modulator includes a quantizer overload protected delta sigma modulator with an N-order feedback-type loop filter. A quantizer of the delta sigma modulator provides feedback to at least the first two filter stages of the loop filter. The loop filter includes at least N successive filter stages and limits an output of an initial filter stage during quantizer overload prevention conditions. If limiting the output of the initial filter stage is insufficient to prevent quantizer overload, the delta sigma modulator can progressively limit an output of at least the next successive filter stage to prevent quantizer overload, where N is a positive integer greater than or equal to two (2).
摘要:
A digital signal processing system includes a delta sigma modulator that maintains a low pass output during quantizer overload prevention conditions. In at least one embodiment, the delta sigma modulator includes a quantizer overload protected delta sigma modulator with an N- order feedback-type loop filter. A quantizer of the delta sigma modulator provides feedback to at least the first two filter stages of the loop filter. The loop filter includes at least N successive filter stages and limits an output of an initial filter stage during quantizer overload prevention conditions. If limiting the output of the initial filter stage is insufficient to prevent quantizer overload, the delta sigma modulator can progressively limit an output of at least the next successive filter stage to prevent quantizer overload, where N is a positive integer greater than or equal to two (2).
摘要:
A sigma-delta modulator (SDM) including n (n≥1) integrators in series, where a first of the n integrators receiving an input signal, at least one Q device, which acts as a quantizer when an absolute value of a signal input thereto is smaller and as a gain element (either with or without offset) when the absolute value of the signal input thereto is larger, and a device for quantizing an output of the unit. The SDM may be a feed back or feed forward SDM. The SDM may include a single or multiple Q devices. The single Q device may be positioned so that the signal input to the one Q device is an output of the last integrator and the output of the one device Ql is input to the device for quantizing and/or to the n integrators. For multiple Q devices, each of the Q devices may have different parameters set to improve stability, improve SNR, and/or reduce introduction of artifacts. The SDM may be part of an analog to digital converter and/or a digital to digital converter. The SDM may process digital or analog signals, for example, a 1-bit signal.
摘要:
A data converter comprises a discrete-time sigma delta modulator e.g. for driving a Class-D power amplifier. The low-pass filter of the sigma delta modulator is modified by adding a suitably positioned pole to lower the oscillation frequency (limit cycle) of the sigma delta modulator in order to obtain increased clustering of the pulses applied to the output of the data converter.
摘要:
A data converter comprises a discrete-time sigma delta modulator e.g. for driving a Class-D power amplifier. The low-pass filter of the sigma delta modulator is modified by adding a suitably positioned pole to lower the oscillation frequency (limit cycle) of the sigma delta modulator in order to obtain increased clustering of the pulses applied to the output of the data converter.
摘要:
Apparatus, and a related method, for converting digital signals directly to radio-frequency (RF) analog signals. The apparatus includes a single high-speed delta-sigma modulator and an integrated upsampler that increases the data rate of digital input samples by a selected factor, such as nine times. The delta-sigma modulator is configured to include a feedback multiplier coefficients that are selected to greatly facilitate operation of associated adders. At least one critical adder includes a carry-select adder modification that further speeds up the add operation and ensures that the apparatus operates at desirably high frequencies.
摘要:
The invention relates to a digital noise shaper circuit for generating an output digital data stream having pre-defined noise characteristics from a multi-bit input digital data stream. The noise shaper circuit includes a greater than two-pole digital filter network (1902-1910) for receiving and processing an error signal to generate the output data stream, a comparator (1924) responsive to the output data stream for generating a feedback signal, a feedback processing network (1926-1934) responsive to the feedback signal for frequency-shaping the feedback signal, and adders (1912-1920) for digitally adding the multi-bit input digital data stream and the frequency-shaped feedback signal to generate the error signal.
摘要:
Sigma-delta modulator comprising a low-pass filter of the Nth order, which is constituted by a series combination of N first-order integrating sections (6.1, 6.2, 6.3, ..., 6.N) comprising each an integrator (12.1, 12.2, 12.3, ..., 12.N) and a limiter (14.1, 14.2, 14.3, ..., 14.N). The individual output signals of the sections are weighted by means of corresponding weighting amplifiers (16.1, 16.2, 16.3, ..., 16.N) and added together in an adder stage (18). The gains of the sections and the limiting values of the limiters are selected so that the last limiter (14.N) in the series arrangement is activated first when the signal level in the sigma-delta modulator increases, subsequently the last-but-one limiter, and so on. This reduces the order of the filter system each time by one when there is an increasing signal level, and causes the sigma-delta modulator to remain stable.