Analog-to-digital converter probe for medical diagnosis and medical diagnosis system

An analog-to-digital converter comprising:

• at least one multiplying digital-to-analog conversion circuit that includes an input node to which an input signal is supplied, an output node which supplies an output signal, and a quantizer which quantizes the input signal based on a reference voltage,
• wherein the output signal of the multiplying digital-to-analog conversion circuit is supplied to the input node of the multiplying digital-to-analog conversion circuit or to the input node of the multiplying digital-to-analog conversion circuit via a different multiplying digital-to-analog conversion circuit,
• wherein the multiplying digital-to-analog conversion circuit includes a capacitance circuit that samples and amplifies the input signal supplied to the input node and supplies the amplified input signal to the output node, and a control circuit that determines a voltage to be supplied to the capacitance circuit in accordance with an output from the quantizer,
• wherein the capacitance circuit includes a first capacitance bank including first and second capacitance elements, each of which includes a first electrode and a second electrode, and a second capacitance bank including third and fourth capacitance elements, each of which includes a first electrode and a second electrode,
• wherein when the input signal is sampled, a normal phase signal corresponding to the input signal is supplied to the first electrodes of the first, second, third, and fourth capacitance elements, and an opposite phase signal with an opposite phase to that of the normal phase signal is supplied to the second electrodes of the first, second, third, and fourth capacitance elements,
• wherein when the input signal is amplified, the first electrodes of the first and second capacitance elements are coupled to the output node, the first electrodes of the third and fourth capacitance elements are coupled to the second electrodes of the first and second capacitance elements, and a voltage from the control circuit is supplied to the second electrodes of the third and fourth capacitance elements,
• wherein the reference voltage is equivalently set in accordance with a capacity ratio of the capacitance elements that are included in the capacitance circuit, and
• wherein when the input signal is amplified, the capacitance circuit supplies the amplified signal, which reflects the output from the quantizer, to the output node by the control circuit determining voltages to be supplied to the second electrodes of the third capacitance element and the fourth capacitance element.

A probe for medical diagnosis comprising:

• a plurality of analog-to-digital converters, each of which receives a measurement target signal as an input signal;
• and
• a digital circuit that receives a digital signal that is converted by the plurality of analog-to-digital converters and outputs a measurement signal based on the digital signal,
• wherein each of the plurality of analog-to-digital converters include
• a quantizer that quantizes a corresponding input signal based on a reference voltage,
• a passive circuit that samples and amplifies the corresponding input signals,
• a buffer circuit that receives an output from the passive circuit, and
• a control circuit that forms a voltage to be supplied to the passive circuit in accordance with an output from the quantizer,
• wherein the passive circuit includes
• a first capacitance element that includes a first electrode to which a normal phase signal corresponding to the input signal is supplied and a second electrode to which an opposite phase signal with an opposite phase to that of the normal phase signal is supplied when the corresponding input signal is sampled, and
• a second capacitance element that includes a first electrode to which the normal phase signal corresponding to the input signal is supplied and a second electrode to which the opposite phase signal with an opposite phase to that of the normal phase signal is supplied when the corresponding input signal is sampled,
• wherein the first electrodes of the first capacitance element and the second capacitance element are coupled to the buffer circuit,
• wherein when the sampled input signal is amplified, a voltage in accordance with the output from the quantizer is supplied from the control circuit to the second electrodes of the first capacitance element and the second capacitance element,
• wherein the reference voltage is equivalently set in accordance with a capacity ratio between the capacitance elements that are included in the passive circuit, and
• wherein the passive circuit supplies an amplified signal, which reflects the output from the quantizer, to the buffer circuit.