A system and method for improving the linearity of a digital-to-analog converter (DAC) is provided. In one embodiment, the system comprises a digital waveform generator that generates a digital sequence associated with a desired analog waveform and a pseudo-random noise component that provides a pulse shaped band limited pseudo-random noise sequence. The system further includes a combiner configured to combine the digital sequence and the pulse shaped band limited pseudo-random noise sequence an...

The invention relates in general to the quantization of digital signal information. More particularly, the invention relates to the reduction of perceptible effects of quantizing noise by reserving a special quantizing level for low-level signals in encoding and decoding applications.

A noise source (113 or 217) is coupled to an analog-to-digital converter (115 or 219) so as to remove at least some unwanted spectral components from the analog-to-digital converter (115 or 219) output. In one embodiment, the noise source (113 or 217) is comprised of a sigma-delta digital-to-analog modulator.

A random number generator (RNG) using an analog-to-digital (A/D) converter to convert random noise into digital samples which are transformed by a reductive mapping into uniformly distributed random numbers for output. The synchronous RNG may be integrated and is intended for use in all computer systems. A noise source provides random noise from electronic events involving quantum-mechanical uncertainty. A compressor amplifies noise by a level-dependent gain to provide random noise, v (t), with ...

Dithering techniques that efficiently combine a non-correlated noise signal with a desired signal are disclosed. Insertion loss in the noise path is relatively low due to combining means employed. In one embodiment, a self-contained dithering module includes a diplexer (or equivalent device) that provides an insertion loss associated with the noise signal of 3 dB or less. The signal+noise output can be used in noise-based application such as a data conversion process.

A dither generating apparatus which generates a sufficiently random auto dither even for a small-level signal and even if the buffer length is short. The LSB of quantized data is extracted and is stored in a buffer memory which serves as an M-bit shift register. An index buffer storing old 2.sup.M indexes is referred to with the M bits. A look-up table, which outputs a random value, is referred to in accordance with the value in the index buffer and outputs a dither. After the reference to the l...

The addition and removal of a dither signal takes place by generation of a first signal (102) and a second signal (104) by a first signal source (151) and a second signal source (152). A dither generator (103) is provided that generates a dither signal (106) that is added to the first signal (102) and subtracted from the second signal (104). The first signal (102) with dither added, and the second signal (104) with dither subtracted enter respective Digital to Analog Converters (DACs) (109, 111)...

A dither circuit is monolitically integrated with a subranging ADC to add a dither signal at the input of the ADC's fine quantizer element to randomize its nonlinear quantization level errors. Because the subranging ADC has at least one overlap bit, the amplitude of the dither signal can range up to at least 2.sup.M-1 LSBs of the fine quantizer without saturating it. The digital equivalent of the dither signal is subtracted at the output of the fine quantizer to maintain the ADC's overall SNR. T...

Using a slurry containing a particulate or fibrous cellulose ester and a wood pulp with a Canadian standard freeness of 100 to 800 ml in a ratio of 10/90 to 90/10 (weight %), a tobacco filter material in the form of a sheet having a nonwoven web structure is produced. The slurry may contain a microfibrillated cellulose in a proportion of 0.1 to 10 weight % on a nonvolatile matter basis. The cellulose ester may be a cellulose acetate with a combined acetic acid in the range of 30 to 62%. This tob...

A dither circuit for improving linearity in A/D or D/A conversion by adding dither to an input signal of an A/D or D/A converter and subtracting dither from an output signal of the A/D or D/A converter. The dither circuit comprises a 1/2 Fs signal generator for generating a 1/2 Fs signal having a frequency which is 1/2 of a sampling frequency Fs, a noise generator for generating random noise in digital form and an adder for adding the 1/2 Fs signal and the random noise together and supplying a r...