Errors in a cyclic analog to digital converter are reduced. An analog to digital converter is a cyclic analog to digital converter for converting an analog input signal into a digital output signal by performing a plurality of times of cycle processing on the analog input signal. A cycle processing unit performs the cycle processing and outputs a digital signal indicating a value of each bit of the digital output signal. An output circuit receives the digital signal output from the cycle processing unit and outputs, as an output signal, a signal obtained by inverting the digital signal every other cycle. A signal input to the cycle processing unit in second and subsequent cycles is generated in the cycle processing in a previous cycle. In the cycle processing, processing for inverting the signal input to the cycle processing is performed.

Errors in a cyclic analog to digital converter are reduced. An analog to digital converter is a cyclic analog to digital converter for converting an analog input signal into a digital output signal by performing a plurality of times of cycle processing on the analog input signal. A cycle processing unit performs the cycle processing and outputs a digital signal indicating a value of each bit of the digital output signal. An output circuit receives the digital signal output from the cycle processing unit and outputs, as an output signal, a signal obtained by inverting the digital signal every other cycle. A signal input to the cycle processing unit in second and subsequent cycles is generated in the cycle processing in a previous cycle. In the cycle processing, processing for inverting the signal input to the cycle processing is performed.

A field measuring device includes a sensor, a measuring transducer, and interface electronics. The interface electronics include a measuring and control device, and first and second terminals for connecting an external electrical device. A current controller and a current measuring device are connected in series in a terminal current path between the first and second terminals. The interface electronics has a voltage source that can be switched on in the terminal current path and disconnected from the terminal current path, so that the voltage source can drive a current in the terminal current path in the switched-on state and in the case of a connected external electrical device. The measuring and control device actuates and reads the current controller, the current measuring device, and the voltage source such that a current signal is output or input via the first and second terminals when an external device is connected.

An Analog to Digital (ADC) is provided, where the ADC may include a sample and hold circuitry to sample an analog input signal, and a summation block to iteratively generate a subtraction signal. The subtraction signal may be based on a difference between the analog input signal and a feedback signal. The ADC may further include a common input stage to receive the subtraction signal, and a plurality of comparison and latch circuitries arranged in parallel, where individual ones of the plurality of parallel comparison and latch circuitries may sequentially receive an output of the common input stage.

An Analog to Digital (ADC) is provided, where the ADC may include a sample and hold circuitry to sample an analog input signal, and a summation block to iteratively generate a subtraction signal. The subtraction signal may be based on a difference between the analog input signal and a feedback signal. The ADC may further include a common input stage to receive the subtraction signal, and a plurality of comparison and latch circuitries arranged in parallel, where individual ones of the plurality of parallel comparison and latch circuitries may sequentially receive an output of the common input stage.

A field measuring device includes a sensor, a measuring transducer, and interface electronics. The interface electronics include a measuring and control device, and first and second terminals for connecting an external electrical device. A current controller and a current measuring device are connected in series in a terminal current path between the first and second terminals. The interface electronics has a voltage source that can be switched on in the terminal current path and disconnected from the terminal current path, so that the voltage source can drive a current in the terminal current path in the switched-on state and in the case of a connected external electrical device. The measuring and control device actuates and reads the current controller, the current measuring device, and the voltage source such that a current signal is output or input via the first and second terminals when an external device is connected.

An analog-to-digital converter includes an adder configured to add an input signal and a feedback signal generated based on the input signal and output an output signal as the result, a successive approximation register analog-to-digital converter (SAR ADC) configured to output a differential signal corresponding to a difference between a digital output signal obtained by quantizing the output signal output from the adder and the input signal, and a bandpass filter circuit configured to perform bandpass filtering on the differential signal output from the SAR ADC and to output the feedback signal according to a result of the bandpass filtering.

An analog-to-digital converter includes an adder configured to add an input signal and a feedback signal generated based on the input signal and output an output signal as the result, a successive approximation register analog-to-digital converter (SAR ADC) configured to output a differential signal corresponding to a difference between a digital output signal obtained by quantizing the output signal output from the adder and the input signal, and a bandpass filter circuit configured to perform bandpass filtering on the differential signal output from the SAR ADC and to output the feedback signal according to a result of the bandpass filtering.

Embodiments of the present invention provide a digital-to-analog conversion circuit, where the digital-to-analog conversion circuit includes a signal amplitude detector and a digital-to-analog converter. When the signal amplitude detector detects a low signal amplitude, a first current module in the digital-to-analog converter operates normally and a second current module in the digital-to-analog converter stops operating. In addition, when stopping operating, the second current module is in a state of a third bias voltage and a fourth bias voltage that are generated by a second bias circuit. When the amplitude detector detects a high signal amplitude subsequently, the second current module resumes normal operation. After operating normally, the second current module switches back to a first bias voltage and a second bias voltage that are generated by a first bias circuit. This reduces a nonlinearity problem caused before a second current module resumes normal operation.

A system can include an analog input port; a digital output port; and a successive approximation register (SAR) analog-to-digital converter (ADC). The SAR ADC can include a voltage comparator V.sub.d having a first input, a second input, and an output; a first plurality of capacitors C.sub.p[0:n] that are coupled with the analog input port and each have a top plate and a bottom plate; a second plurality of capacitors C.sub.n[0:n] that are coupled with the analog input port and each have a top plate and a bottom plate; and a SAR controller coupled between the output of the voltage comparator V.sub.d and the digital output port.