US 6,144,232 AGranted

Chopper type voltage comparing circuit capable of correctly determining output polarity, and voltage comparing method

AssigneeNEC Corporation

InventorsAkira Yukawa, Toshio Ohkido

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Abstract

A highspeed voltage comparing operation by a voltage comparing circuit is realized while input sampling timing can be made constant. This voltage comparing circuit is mainly arranged by a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, a eighth switch, a first capacitor, a second capacitor, a first inverter, a second inverter, a third capacitor, and a fourth capacitor. In this voltage comparing circuit, an input signal voltage is held in the first capacitor and also a reference voltage is held in the second capacitor in an input sampling mode. Then, electron charges stored in these capacitors are redistributed, and the difference voltage between the input voltage and the reference voltage is amplified by two sets of inverters in an amplifying mode. In a latch mode, these first and second inverters are operated as a flip-flop circuit. Consequently, in this voltage comparing circuit, the sampling timing of the input voltages can be correctly and periodically determined, so that the precision of the input signal comparing process operation can be improved.

Claims30

Dependent claims

A voltage comparing circuit comprising:

a first switch turned ON/OFF between a plus-sided voltage of an analog input signal and one terminal of a first capacitor;
a second switch turned ON/OFF between a minus-sided voltage of the analog input signal and one terminal of a second capacitor;
a third switch turned ON/OFF between a plus-sided voltage of a reference voltage and said one terminal of the first capacitor;
a fourth switch turned ON/OFF between a minus-sided voltage of the reference voltage and said one terminal of the second capacitor;
a first inverter connected between an input terminal thereof and the other terminal of said first capacitor;
a second inverter connected between an input terminal thereof and the other terminal of said second capacitor;
a fifth switch turned ON/OFF between the input terminal of the first inverter and an output terminal thereof;
a sixth switch turned ON/OFF between the input terminal of said second inverter and an output terminal thereof;
a seventh switch turned ON/OFF via a third capacitor between the input terminal of the first inverter and the output terminal of the second inverter;
and
an eighth switch turned ON/OFF via a fourth capacitor between the input terminal of the second inverter and the output terminal of the first inverter;
wherein:
said first, second, fifth, sixth, seventh, and eighth switches are turned ON whereas said third and fourth switches are turned OFF in a first operation mode;
said third and fourth switches are turned ON whereas said first, second, fifth, sixth, seventh, and eighth switches are turned OFF in a second operation mode subsequent to said first operation mode;
and
said third, fourth, seventh, and eighth switches are turned ON whereas said first, second, fifth, and sixth switches are turned OFF in a third operation mode subsequent to said second operation mode, whereby a series of said switching operations is repeatedly carried out so as to compare the voltage of said analog input signal with said reference voltage.

13 more elements

A voltage comparing circuit comprising:

a first switch turned ON/OFF between an analog input signal and one terminal of a first capacitor;
a second switch turned ON/OFF between a reference voltage and one terminal of a second capacitor;
a third switch turned ON/OFF between said one terminal of the first capacitor and said one terminal of the second capacitor;
a first inverter connected between an input terminal thereof and the other terminal of said first capacitor;
a second inverter connected between an input terminal thereof and the other terminal of said second capacitor;
a fourth switch turned ON/OFF between the input terminal of the first inverter and an output terminal thereof;
a fifth switch turned ON/OFF between the input terminal of said second inverter and an output terminal thereof;
a sixth switch turned ON/OFF via a third capacitor between the input terminal of the first inverter and the output terminal of the second inverter;
and
a seventh switch turned ON/OFF via a fourth capacitor between the input terminal of the second inverter and the output terminal of the first inverter;
wherein:
said first, second, fourth, fifth, sixth, and seventh switches are turned ON whereas said third switch is turned OFF in a first operation mode;
said third switch is turned ON whereas said first, second, fourth, fifth, sixth, and seventh switches are turned OFF in a second operation mode subsequent to said first operation mode;
and
said third, sixth, and seventh switches are turned ON whereas said first, second, fourth, and fifth switches are turned OFF in a third operation mode subsequent to said second operation mode, whereby a series of said switching operations is repeatedly carried out so as to compare the voltage of said analog input signal with said reference voltage.

12 more elements

Dependencies are inferred from the claim text.