Differential comparator circuit
AssigneeSTMicroelectronics (Grenoble 2) SAS
InventorLaurent Simony
Life of this patent
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Abstract
A differential comparator circuit includes a voltage amplifier of negative gain receiving an analog input signal and generating an inverted analog input signal. The analog input signal and the inverted analog input signal form differential analog input signals. A comparator input circuit includes a first capacitive divider to generate a first signal as an average of the analog input signal and a first ramp signal, and a second capacitive divider to generate a second signal as an average of the inverted analog input signal and a second ramp signal, with the first and second ramp signals being differential ramp signals. The comparator is configured to compare the first and second signals to generate a signal transition having a timing based on the input signal.
Claims14
An electronic circuit comprising a differential comparator circuit, the differential comparator circuit comprising:
- a voltage amplifier of negative gain configured to receive an analog input signal and to generate an inverted analog input signal, wherein the analog input signal and the inverted analog input signal form differential analog input signals;
- and
- a comparator input circuit comprising:
- a first capacitive divider configured to generate a first signal as an average of the analog input signal and a first ramp signal;
- and
- a second capacitive divider configured to generate a second signal as an average of the inverted analog input signal and a second ramp signal, wherein the first and second ramp signals are differential ramp signals;
- wherein the differential comparator circuit is configured to compare the first signal with the second signal in order to generate a signal transition having a timing based on the analog input signal.
An electronic circuit comprising a differential amplifier circuit, the differential amplifier circuit comprising:
- a swapping circuit configured to couple, during a first time period, a first capacitor between a first input node and a common node and a second capacitor between a second node and the common node, and to couple, during a second time period, the first capacitor between the second node and the common node and the second capacitor between the first input node and the common node;
- the swapping circuit comprising:
- a first switch coupled between the first input node and a first electrode of the first capacitor;
- a second switch coupled between the second node and the first electrode of the first capacitor;
- a third switch coupled between the second node and a first electrode of the second capacitor;
- and
- a fourth switch coupled between the first input node and the first electrode of the second capacitor,
- wherein a second electrode of the first capacitor and a second electrode of the second capacitor are coupled to the common node;
- and
- a control circuit configured to:
- control, during the first time period, the first and third switches to be conductive and the second and fourth switches to be non-conductive;
- and
- control, during the second time period, the second and fourth switches to be conductive and the first and third switches to be non-conductive, such that roles of the first and second capacitors are swapped between the first and second time periods.
A method of differential comparison, comprising:
- receiving, by a voltage amplifier of negative gain, an analog input signal and generating, by the voltage amplifier, an inverted analog input signal, wherein the analog input signal and the inverted analog input signal form differential analog input signals;
- generating, by a first capacitive divider of a comparator input circuit, a first signal as an average of the analog input signal and a first ramp signal;
- generating, by a second capacitive divider of the comparator input circuit, a second signal as an average of the inverted analog input signal and a second ramp signal, wherein the first and second ramp signals are differential ramp signals;
- and
- comparing, the first signal with the second signal to generate a signal transition at a time based on the analog input signal.
Dependencies are inferred from the claim text.