Bootstrapped sampling switch circuits and systems

An analog to digital converter integrated circuit, comprising:

• a plurality of inputs each configured to receive an analog input signal;
• a plurality of resettable delta sigma analog to digital converter stages, each comprising:
• a plurality of driver circuits, each coupled to a respective one of the plurality of inputs, each comprising an amplifier and an integrator capacitor and outputting a sampled input voltage;
• a plurality of switched capacitor input stages, each coupled to receive at least one of the sampled input voltages at an input, each of the switched capacitor input stages further comprising:
• the input receiving the sampled input voltages and coupled to a source terminal of a MOS transistor;
• an output at a drain terminal of the MOS transistor coupled to one plate of a sampling capacitor;
• a first switch coupling the input to a gate terminal of the MOS transistor, responsive to an initial phase control signal;
• a bootstrap capacitor having a top plate coupled to a gate terminal of the MOS transistor and to the first switch;
• a second switch coupling a bottom plate of the bootstrap capacitor to a first low voltage supply responsive to the initial phase control signal;
• a third switch coupling the bottom plate of the bootstrap capacitor to a positive voltage supply greater than the first low voltage supply responsive to a first phase periodic control signal;
• and
• a fourth switch coupling the bottom plate of the bootstrap capacitor to a second low voltage supply lower than the first low voltage supply, responsive to a second phase periodic control signal.

A system for imaging, comprising:

• an apparatus for creating images comprising a plurality of radiation emitters spaced from and directed towards a plurality of photo-detectors sensitive to the emitted radiation, the plurality of photo-detectors outputting analog output signals corresponding to an intensity of the radiation received at the photo-detectors;
• at least one analog-to-digital converter integrated circuit having a plurality of inputs coupled to receive analog output signals from the plurality of photo-detectors, and further comprising:
• a plurality of analog to digital converter stages including an analog-to-digital converter stage configured to output digital data corresponding to the analog output signals, each of the analog to digital converter stages comprising:
• a plurality of driver circuits, each coupled to a respective one of the plurality of inputs, each comprising an amplifier and a capacitor coupled to sample an analog signal and each outputting a corresponding input voltage;
• a plurality of switched capacitor input stages, each coupled to the output of at least one of the driver circuits, each of the switched capacitor input stages further comprising:
• a MOS sampling transistor having a current conduction path coupled between the input voltage and an output, and having a gate terminal;
• one plate of a sampling capacitor coupled to the output of the MOS sampling transistor;
• a first switch coupling the input voltage to the gate terminal of the MOS sampling transistor, responsive to an initial phase control signal;
• a bootstrap capacitor having a top plate coupled to the gate terminal of the MOS sampling transistor and to the first switch;
• a second switch coupling a bottom plate of the bootstrap capacitor to a first low voltage supply responsive to the initial phase control signal;
• a third switch coupling the bottom plate of the bootstrap capacitor to a positive voltage supply greater than the first low voltage supply, responsive to a first phase periodic control signal;
• and
• a fourth switch coupling the bottom plate of the bootstrap capacitor to a second low voltage supply lower than the first low voltage supply, responsive to a second phase periodic control signal.