Abstract: Digital audio tone control implemented using Shelving filters for the digital audio treble tone control exhibits artifacts (noise, distortion, etc.) as the tone control settings are changed. This was previously accomplished by changing filter coefficients in the traditional small equal (on a dB scale) filter steps of a fraction of 1 dB. While this worked for bass filters, artifacts were still present for treble. This invention eliminates these artifacts by changing the filter steps to small equal steps on a linear scale. Additionally, where the steps became too large for the resolution required, additional filter steps are added. Approximately 150 filter steps are used for treble control and 128 filter steps are used for bass tone control. An efficient way of implementing the filter steps for digital tone control stores (119) one set of filter coefficient values and a small amount of additional information and then increments the coefficients between all the other steps.

Abstract: A system and method of integrating digital switching amplifiers into systems with low amplitude front-end tuners, among other things, to eliminate shielding and EMI filtering associated with signals, power and ground. An adaptive frequency programmable pulse frame rate digital switching amplifier scheme using either look-up tables or appropriate algorithms, ensures by design, the elimination of critical interference frequency generation.

Abstract: A system and method of integrating switching amplifiers into systems with low amplitude front-end tuners to eliminate shielding and EMI filtering associated with signals, power and ground. An adaptive frequency programmable pulse frame rate switching amplifier scheme using either look-up tables or appropriate algorithms, ensures by design, the elimination of critical interference frequency generation.

Abstract: A digital amplifier includes a noise shaper and a dither generator arranged to introduce noise to the shaper. The generator uses a seed value derived from a state variable of the shaper.

Abstract: A system and method of integrating switching amplifiers into systems with low amplitude front-end tuners to eliminate shielding and EMI filtering associated with signals, power and ground. An adaptive frequency programmable pulse frame rate switching amplifier scheme using either look-up tables or appropriate algorithms, ensures by design, the elimination of critical interference frequency generation.

Abstract: A voltage reference circuit includes: an amplifier A1 with low open loop output impedance, an output of the amplifier is coupled to a first input of the amplifier A1; and a first resistor R1 coupled between the output of the amplifier A1 and a reference node 30, the first resistor R1 has a resistance substantially equally to the low open loop output impedance, whereby a low frequency impedance at the reference node 30 is substantially equal to the resistance.