CDAC operation at low supply voltages

A CDAC circuit configured for operation at low supply voltages, said CDAC circuit comprising:

• a bit switch circuit comprising at least one bit switch, said bit switch circuit configured to facilitate sampling of an input voltage;
• at least one sampling capacitor coupled to said at least one bit switch;
• a comparator device for determining the value of a sampled charge on said sampling capacitor;
• and
• a gate-boosting circuit coupled to said bit switch circuit, said gate-boosting circuit comprising:
• a pair of N-channel transistor devices comprising a pre-charging transistor and a discharging transistor;
• and
• a charging capacitor coupled to said pair of N-channel transistor devices that can be suitably charged to provide a boosted voltage signal to a transmission gate of said bit switch circuit;
• and
• wherein said gate-boosting circuit is configured to permit said bit switch circuit to operate at a reference voltage of less than 2.5 volts,
• wherein said bit switch circuit includes a transmission gate comprising a P-channel device and an N-channel device, respective drains of said P-channel device and said N-channel device being connected together to a reference voltage, and respective sources of said P-channel device and said N-channel device being connected to said at least one sampling capacitor;
• and
• wherein an output of said gate-boosting circuit is coupled to a gate electrode of said N-channel device to provide a boosted voltage signal to said transmission gate of said bit switch circuit.

A CDAC circuit configured for operation at low supply voltages, said CDAC circuit comprising:

• a bit switch circuit comprising at least one bit switch, said bit switch circuit configured to facilitate sampling of an input voltage;
• at least one sampling capacitor coupled to said at least one bit switch;
• a comparator device for determining the value of a sampled charge on said sampling capacitor;
• and
• a gate-boosting circuit coupled to said bit switch circuit, said gate-boosting circuit comprising:
• a pair of N-channel transistor devices comprising a pre-charging transistor and a discharging transistor;
• and
• a charging capacitor coupled to said pair of N-channel transistor devices that can be suitably charged to provide a boosted voltage signal to a transmission gate of said bit switch circuit;
• and
• wherein said gate-boosting circuit is configured to permit said bit switch circuit to operate at a reference voltage of less than 2.5 volts,
• said pre-charging transistor and said discharging transistor being connected in a series arrangement, and wherein a drain of said pre-charging transistor is coupled to a voltage source, a source of said pre-charging transistor is coupled to a drain of said discharging transistor, a source of said discharging transistor is coupled to a ground terminal, and a bottom plate of said charging capacitor is coupled to said drain of said discharging transistor,
• wherein said CDAC circuit further comprises a logic circuit configured for providing control functions to said gate-boosting circuit, and for facilitating control of operation for said bit switch circuit.

A CDAC circuit configured for operation at low supply voltages, said CDAC circuit comprising:

• a bit switch circuit comprising at least one bit switch, said bit switch circuit configured to facilitate sampling of an input voltage;
• at least one sampling capacitor coupled to said at least one bit switch;
• a comparator device for determining the value of a sampled charge on said sampling capacitor;
• and
• a gate-boosting circuit coupled to said bit switch circuit, said gate-boosting circuit comprising:
• a pair of N-channel transistor devices comprising a pre-charging transistor and a discharging transistor;
• and
• a charging capacitor coupled to said pair of N-channel transistor devices that can be suitably charged to provide a boosted voltage signal to a transmission gate of said bit switch circuit;
• and
• wherein said gate-boosting circuit is configured to permit said bit switch circuit to operate at a reference voltage of less than 2.5 volts,
• wherein said CDAC circuit comprises a gate-boosting circuit having an output coupled to an auto-zero switch of said comparator device.

A gate-boosting circuit for facilitating the low voltage operation of a CDAC circuit, said gate-boosting circuit comprising:

• a pair of N-channel transistor devices comprising a pre-charging transistor and a discharging transistor;
• and
• a charging capacitor coupled to said pair of N-channel transistor devices that can be suitably charged to provide a boosted voltage signal;
• and
• wherein said gate-boosting circuit is configured for provide the gate boosted voltage signal to the CDAC circuit to permit said CDAC circuit to operate at a reference voltage of less than 2.5 volts,
• said pre-charging transistor and said discharging transistor being connected in a series arrangement, and wherein a drain of said pre-charging transistor is coupled to a voltage source, a source of said pre-charging transistor is coupled to a drain of said discharging transistor, a source of said discharging transistor is coupled to a ground terminal, and a bottom plate of said charging capacitor is coupled to said drain of said discharging transistor,
• wherein said gate-boosting circuit further comprises an inverter device, said inverter device being coupled between a gate electrode of said pre-charging transistor and a top plate of said charging capacitor.

A gate-boosting circuit for facilitating the low voltage operation of a CDAC circuit, said gate-boosting circuit comprising:

• a pair of N-channel transistor devices comprising a pre-charging transistor and a discharging transistor;
• and
• a charging capacitor coupled to said pair of N-channel transistor devices that can be suitably charged to provide a boosted voltage signal;
• and
• wherein said gate-boosting circuit is configured for provide the gate boosted voltage signal to the CDAC circuit to permit said CDAC circuit to operate at a reference voltage of less than 2.5 volts,
• wherein said gate-boosting circuit is configured to provide the gate boosted voltage signal to a bit switch circuit to permit said bit switch circuit to operate at a reference voltage of less than 2.5 volts.

A gate-boosting circuit for facilitating the low voltage operation of a CDAC circuit, said gate-boosting circuit comprising:

• a pair of N-channel transistor devices comprising a pre-charging transistor and a discharging transistor;
• and
• a charging capacitor having a bottom plate being coupled to a source of said pre-charging transistor and a drain of said discharging transistor;
• said charging capacitor capable of being charged to provide a boosted voltage signal;
• an inverter device being coupled between a gate electrode of said pre-charging transistor and a top plate of said charging capacitor, and
• wherein said gate-boosting circuit is configured to provide the boosted voltage signal to the CDAC circuit to permit said CDAC circuit to operate at a reference voltage of less than 2.5 volts.

A method for providing low voltage operation of a CDAC circuit, said method comprising the steps of:

• pre-charging a charging capacitor with a pre-charging transistor during a first half clock cycle;
• raising a voltage potential of a lower plate of the pre-charged capacitor to a maximum available supply voltage to provide a full voltage charge for the charging capacitor;
• and
• applying the full voltage charge from said charging capacitor to provide a gate-boosted voltage charge to the CDAC circuit to facilitate low voltage operation.