Sample-and-hold amplifier circuit and pipelined A/D and D/A converters using sample hold amplification circuit

A sample-and-hold amplifier circuit, comprising:

• a sampling circuit that carries out a sampling of an input signal;
• and
• an operational amplifier that carries out an operational amplification of the input signal that has been subjected to the sampling by the sampling circuit,
• wherein the operational amplifier includes:
• multiple operational amplifier stages that are connected with each other in a series manner;
• a switch, that (a) connects or cuts off a connection of the operational amplifier stages, (b) is nonconductive during a first operation phase during which the sampling is carried out, and (c) is conductive in a second operation phase during which the operational amplification is carried out by the operational amplifier as a whole, said switch being provided between either one pair of neighboring first and second operational amplifier stages so as to be provided between an output terminal of the first operational amplifier stage and an input terminal of the second operational amplifier stage;
• and
• phase compensation capacitors provided between an output terminal of a final operational amplifier stage and at least the input terminal of the second operational amplifier stage.

A pipelined A/D converter, comprising:

• at least one first sub-A/D converter blocks, connected with each other in a series manner, that include (a) a sub-A/D converter that converts an input signal into a predetermined-numbered bit information and (b) a sub-operatinal-circuit which converts the bit information into an analog value, carries out an operational amplification with respect to a difference between the analog value and the input signal so as to output the difference that has been subjected to the operational amplification, and
• a second sub-A/D converter block that includes a sub-A/D converter which converts an output signal of the first sub-A/D converter block of a final stage into the remainder of the bit information,
• said sub-operatinal-circuit being a sample-and-hold amplifier circuit that includes:
• a sampling circuit that carries out a sampling of the input signal;
• and
• an operational amplifier that carries out an operational amplification of the input signal that has been subjected to the sampling by the sampling circuit,
• said operational amplifier including:
• first and second operational amplifier stages that are connected in this order in a series manner;
• a switch, provided between an output terminal of the first operational amplifier stage and an input terminal of the second operational amplifier stage, that connects or cuts off connection of a connection of the first and second operational amplifier stages so as to be nonconductive in a first operation phase during which the sampling is carried out and so as to be conductive in a second operation phase during which the operational amplifier, as a whole, carries out the operational amplification;
• and
• a phase compensation capacitor provided between an output terminal and the input terminal of the second operational amplifier stage.

A pipelined A/D converter, comprising:

• at least one first sub-A/D converter blocks, connected with each other in a series manner, that include (a) a sub-A/D converter that converts an input signal into a predetermined-numbered bit information and (b) a sub-operatinal-circuit which converts the bit information into an analog value, carries out an operational amplification with respect to a difference between the analog value and the input signal so as to output the difference that has been subjected to the operational amplification, and
• a second sub-A/D converter block that includes a sub-A/D converter which converts an output signal of the first sub-A/D converter block of the final stage into the remainder of the bit information,
• said sub-operatinal-circuit being a sample-and-hold amplifier circuit that includes:
• a sampling circuit that carries out a sampling of the input signal;
• and
• an operational amplifier that carries out an operational amplification of the input signal that has been subjected to the sampling by the sampling circuit,
• said operational amplifier including:
• multiple operational amplifier stages that are connected with each other in a series manner;
• a switch, that (a) connects or cuts off a connection of the operational amplifier stages, (b) is nonconductive during the first operation phase during which the sampling is carried out, and (c) is conductive in the second operation phase during which the operational amplification is carried out by the operational amplifier as a whole, said switch being provided between either one pair of neighboring first and second operational amplifier stages so as to be provided between an output terminal of the first operational amplifier stage and an input terminal of the second operational amplifier stage;
• and
• phase compensation capacitors provided between an output terminal of a final operational amplifier stage and at least the input terminal of the second operational amplifier stage.

A pipelined D/A converter, comprising:

• a plurality of sample-and-hold circuits that are connected with each other in a series manner and are used as a sub-D/A converter that converts a predetermined-numbered bit information of a digital signal into an analog value,
• the sub-D/A converter carrying out an operational amplification with respect to an analog input signal and an analog signal that corresponds to the predetermined-numbered bit information and send it to a sub-D/A converter of the next stage so that the sub-D/A converter of the final stage outputs an analog signal corresponding to the digital signal,
• the sample-and-hold amplifier circuit, including:
• a sampling circuit that carries out a sampling of an input signal;
• and
• an operational amplifier that carries out an operational amplification of the input signal that has been subjected to the sampling by the sampling circuit,
• the operational amplifier including:
• first and second operational amplifier stages that are connected in this order in a series manner;
• a switch, provided between an output terminal of the first operational amplifier stage and an input terminal of the second operational amplifier stage, that connects or cuts off connection of a connection of the first and second operational amplifier stages so as to be nonconductive in a first operation phase during which the sampling is carried out and so as to be conductive in a second operation phase during which the operational amplifier, as a whole, carries out the operational amplification;
• and
• a phase compensation capacitor provided between an output terminal and the input terminal of the second operational amplifier stage.

A pipelined D/A converter, comprising:

• a plurality of sample-and-hold circuits that are connected with each other in a series manner and are used as a sub-D/A converter that converts a predetermined-numbered bit information of a digital signal into an analog value,
• the sub-D/A converter carrying out an operational amplification with respect to an analog input signal and an analog signal that corresponds to the predetermined-numbered bit information and send it to a sub-D/A converter of the next stage so that the sub-D/A converter of the final stage outputs an analog signal corresponding to the digital signal,
• the sample-and-hold amplifier circuit, including:
• a sampling circuit that carries out a sampling of an input signal;
• and
• an operational amplifier that carries out an operational amplification of the input signal that has been subjected to the sampling by the sampling circuit,
• said operational amplifier including:
• multiple operational amplifier stages that are connected with each other in a series manner;
• a switch, that (a) connects or cuts off a connection of the operational amplifier stages, (b) is conductive during the first operation phase during which the sampling is carried out, and (c) is nonconductive in the second operation phase during which the operational amplification is carried out by the operational amplifier as a whole, said switch being provided between either one pair of neighboring first and second operational amplifier stages so as to be provided between an output terminal of the first operational amplifier stage and an input terminal of the second operational amplifier stage;
• and
• phase compensation capacitors provided between an output terminal of a final operational amplifier stage and at least the input terminal of the second operational amplifier stage.