A wireless cellular telephone with an audio codec for converting digital audio signals to analog audio signals. The audio codec comprises two digital audio bus interfaces for coupling to respective digital audio buses, and a digital-only signal path between the two digital audio bus interfaces, such that no analog processing of the audio signals occurs in the digital-only signal path.

A wireless cellular telephone with an audio codec for converting digital audio signals to analog audio signals. The audio codec comprises two digital audio bus interfaces for coupling to respective digital audio buses, and a digital-only signal path between the two digital audio bus interfaces, such that no analog processing of the audio signals occurs in the digital-only signal path.

A circuit includes a first transistor and a second transistor having respective control terminals coupled to receive first and second bias voltages. A first electronic switch is coupled in series with, and between current paths of the first and second transistors to provide an output current line between a circuit output node and ground. A second electronic switch is selectively activated to a conductive state in order to provide a charge transfer current path between a bias node and a charge transfer node in the output current line. A third electronic switch is selectively activated to a conductive state in order to provide a charge transfer current path between the charge transfer node and the control terminal of the second transistor.

A circuit includes a first transistor and a second transistor having respective control terminals coupled to receive first and second bias voltages. A first electronic switch is coupled in series with, and between current paths of the first and second transistors to provide an output current line between a circuit output node and ground. A second electronic switch is selectively activated to a conductive state in order to provide a charge transfer current path between a bias node and a charge transfer node in the output current line. A third electronic switch is selectively activated to a conductive state in order to provide a charge transfer current path between the charge transfer node and the control terminal of the second transistor.

A dither is an uncorrelated signal, usually pseudo-random noise injected into the input of an ADC such that a given input value of the wanted signal becomes spread over a plurality of codes. This reduces the effect of DNL and also smooths the integral non-linearity (INL) response of the ADC. The advantages of introducing dither could be obtained without having to perturb the signal input to the ADC. This avoids the introduction of additional components in the ADC. The dither can be applied to the components used to form a residue of the ADC stage within a pipelined converter. For example, a dither can be applied solely to a DAC part or different dithers can be applied to a ADC and DAC parts respectively. This allows greater flexibility of linearization of the ADC response and the formation of an analog residue by the DAC.

A converter circuit is used to selectively convert an analog input voltage into a digital output signal or a digital input signal into an analog output voltage as a function of a mode signal. The converter circuit includes a control circuit configured to generate a start-of-conversion signal. A ramp generator is configured to, when the mode signal indicates an analog-to-digital conversion, generate a timer stop signal after a time interval that is determined as a function of the value of the analog input voltage, thereby implementing an analog-to-time conversion. When the mode signal indicates a digital-to-analog conversion, ramp generator is configured to vary the ramp signal until a ramp stop signal is set and, in response to the ramp stop signal, determine the analog output voltage as a function of the ramp signal, thereby implementing a time-to-analog conversion.

A converter circuit is used to selectively convert an analog input voltage into a digital output signal or a digital input signal into an analog output voltage as a function of a mode signal. The converter circuit includes a control circuit configured to generate a start-of-conversion signal. A ramp generator is configured to, when the mode signal indicates an analog-to-digital conversion, generate a timer stop signal after a time interval that is determined as a function of the value of the analog input voltage, thereby implementing an analog-to-time conversion. When the mode signal indicates a digital-to-analog conversion, ramp generator is configured to vary the ramp signal until a ramp stop signal is set and, in response to the ramp stop signal, determine the analog output voltage as a function of the ramp signal, thereby implementing a time-to-analog conversion.

A DAC driver includes a number of DAC drivers coupled to a load network. A first DAC driver includes a first set of data switches that can be controlled by a first digital input signal. The first DAC driver further includes a first set of output switches, a first set of dump switches and a first set of current sources. Another DAC driver includes a second set of output switches, dump switches, and current sources. The first set of output switches or the second set of output switches are operable to respectively couple either one of the first set of data switches or the first set of current sources to the load network. The first set of dump switches or the second set of dump switches are operable to respectively dump the first set of current sources or the second set current sources into a respective dump load.

A digital-to-analog conversion circuit (DAC) is operable to convert an input digital signal to an output analog signal. The DAC comprises a digital signal processing circuit operable to process the input digital signal according to a first transfer function to generate a first processed digital signal and process the digital input signal according to a second transfer function to generate a second processed digital signal. The DAC comprises a first unit DAC operable to convert the first processed digital signal to a first intermediate analog signal, and a second unit DAC operable to convert the second processed digital signal to a second intermediate analog signal. The DAC comprises switching circuits and a combiner circuit to generate the output analog signal from the intermediate analog signals.

A digital-to-analog conversion circuit (DAC) is operable to convert an input digital signal to an output analog signal. The DAC comprises a digital signal processing circuit operable to process the input digital signal according to a first transfer function to generate a first processed digital signal and process the digital input signal according to a second transfer function to generate a second processed digital signal. The DAC comprises a first unit DAC operable to convert the first processed digital signal to a first intermediate analog signal, and a second unit DAC operable to convert the second processed digital signal to a second intermediate analog signal. The DAC comprises switching circuits and a combiner circuit to generate the output analog signal from the intermediate analog signals.