Abstract:
The present invention relates in one aspect to a DC linear voltage regulator circuit for generating a regulated DC output voltage based on a DC input voltage. The DC linear voltage regulator circuit comprises a DMOS pass transistor comprising drain, gate, source and bulk terminals wherein the drain terminal is connected to a regulator output which is configured to supply the regulated DC output voltage and the source terminal is connected to a regulator input for receipt of the DC input voltage. The DC linear voltage regulator circuit comprises a switchable leakage prevention circuit, connected to the bulk terminal of the DMOS pass transistor, and configured to automatically detect and interrupt a flow of leakage current from the regulator output to the bulk terminal.
Abstract:
A sigma-delta modulator circuit selectively removes a dither signal previously added to an input of a quantizer circuit from the quantizer circuit output when addition of the dither signal causes a digital state change in the quantizer circuit output. Various examples for enabling the selective removal of the dither signal are described. In one embodiment, a second quantizer circuit provides a non-dithered output signal for comparison, by a digital comparator, with the dithered output signal. In another embodiment, a single quantizer circuit provides the dithered and non-dithered output signals in turn, for comparison. A subtraction circuit may remove the dither signal as appropriate. Embodiments enable retention of the improved limit cycle tone reduction achievable via dithering while reducing the need for circuits with increased signal headroom, and associated design complexity and power dissipation.
Abstract:
A transducer amplification circuit may include a preamplifier circuit with a signal input receiving a transducer signal to provide an amplified transducer signal comprising audible frequency components and ultrasonic frequency components. The transducer amplification circuit may include a first sigma-delta modulator configured to sample and quantize the amplified transducer signal to generate a first digital transducer signal comprising a first quantization noise signal. The first sigma-delta modulator may include a first noise transfer function having a high pass response in at least a portion of an audible frequency range to push the quantization noise signal to ultrasonic frequencies. A second sigma-delta modulator is configured to sample and quantize the amplified transducer signal to generate a second digital transducer signal comprising a second quantization noise signal. The second sigma-delta modulator may include a second noise transfer function with a magnitude minimum placed at the ultrasonic frequencies.
Abstract:
The present invention relates in one aspect to a DC linear voltage regulator circuit for generating a regulated DC output voltage based on a DC input voltage. The DC linear voltage regulator circuit comprises a DMOS pass transistor comprising drain, gate, source and bulk terminals wherein the drain terminal is connected to a regulator output which is configured to supply the regulated DC output voltage and the source terminal is connected to a regulator input for receipt of the DC input voltage. The DC linear voltage regulator circuit comprises a switchable leakage prevention circuit, connected to the bulk terminal of the DMOS pass transistor, and configured to automatically detect and interrupt a flow of leakage current from the regulator output to the bulk terminal.