News Column

Patent Issued for Apparatus and Methods for Voltage Comparison

September 3, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventor Li, Hongxing (Tokyo, JP), filed on December 21, 2012, was published online on August 19, 2014.

The assignee for this patent, patent number 8810282, is Analog Devices Inc. (Norwood, MA).

Reporters obtained the following quote from the background information supplied by the inventors: "Embodiments of the invention relate to electronic devices, and more particularly, to comparators.

"Certain electronic systems can include a comparator for comparing one input voltage to another input voltage. For example, an analog-to-digital converter (ADC) can include one or more comparators for comparing an input voltage signal to a reference voltage and/or for comparing one input voltage signal to another input voltage signal.

"The performance of a comparator, such as the comparator's noise and/or input offset, can impact the overall performance of the electronic system that the comparator is used in. The comparator's impact on overall operation can be exacerbated in configurations using multiple comparators. For instance, an n-bit flash ADC can include 2.sup.n-1 comparators used for determining a digital value of an analog signal. For example, in a flash ADC, a first input voltage for a comparator can correspond to an input voltage that is being converted from analog to digital, and a second input voltage can be a voltage from a voltage divider network.

"Accordingly, there is a need for improved comparators, including for example, comparators having smaller size, reduced power consumption, low noise, and/or low input offset."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventor's summary information for this patent: "In one embodiment, a comparator includes a first comparator stage configured to receive a first input voltage and a second input voltage. The first comparator stage includes a first input transistor, a second input transistor, a first inverting gain circuit, a second inverting gain circuit, a first capacitor, and a second capacitor. A gate of the first input transistor is configured to receive the first input voltage, and a gate of the second input transistor is configured to receive the second input voltage. Additionally, a source of the first input transistor is electrically connected to a source of the second input transistor. The first inverting gain circuit includes an input and an output, and the input of the first inverting gain circuit is electrically connected to a drain of the first input transistor. The first capacitor includes a first end electrically connected to the drain of the first input transistor and a second end electrically connected to the output of the first inverting gain circuit. The second inverting gain circuit includes an input and an output, and the input of the second inverting gain circuit is electrically connected to a drain of the second input transistor. The second capacitor includes a first end electrically connected to the drain of the second input transistor and a second end electrically connected to the output of the second inverting gain circuit.

"In another embodiment, a method of comparing a first input voltage to a second input voltage is provided. The method includes receiving the first input voltage at a gate of a first input transistor and receiving the second input voltage at a gate of a second input transistor. A source of the first input transistor is electrically connected to a source of the second input transistor. Additionally, the method includes biasing the first and second input transistors with a bias current in response to a clock signal and controlling a first portion of the bias current through the first input transistor relative to a second portion of the bias current through the second input transistor based on a voltage difference between the first and second input voltages. The method further includes loading a drain of the first input transistor using a first capacitance and a first inverting gain circuit. The first inverting gain circuit includes an input electrically connected to the drain of the first input transistor and an output, and the first capacitance is operatively coupled between the drain of the first input transistor and the output of the first inverting gain circuit. The method further includes loading a drain of the second input transistor using a second capacitance and a second inverting gain circuit. The second inverting gain circuit includes an input electrically connected to the drain of the second input transistor and an output, and the second capacitance is operatively coupled between the drain of the second input transistor and the output of the second inverting gain circuit.

"In another embodiment, analog-to digital converter is provided. The analog-to-digital converter includes a comparator configured to receive a first input voltage and a second input voltage. The comparator includes a first input transistor, a second input transistor, a first inverting gain circuit, a second inverting gain circuit, a first capacitor, and a second capacitor. A gate of the first input transistor is configured to receive the first input voltage, and a gate of the second input transistor is configured to receive the second input voltage. Additionally, a source of the first input transistor is electrically connected to a source of the second input transistor. The first inverting gain circuit includes an input and an output, and the input of the first inverting gain circuit is electrically connected to a drain of the first input transistor. The first capacitor includes a first end electrically connected to the drain of the first input transistor and a second end electrically connected to the output of the first inverting gain circuit. The second inverting gain circuit includes an input and an output, and the input of the second inverting gain circuit is electrically connected to a drain of the second input transistor. The second capacitor includes a first end electrically connected to the drain of the second input transistor and a second end electrically connected to the output of the second inverting gain circuit."

For more information, see this patent: Li, Hongxing. Apparatus and Methods for Voltage Comparison. U.S. Patent Number 8810282, filed December 21, 2012, and published online on August 19, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8810282.PN.&OS=PN/8810282RS=PN/8810282

Keywords for this news article include: Analog Devices Inc., Medical Device Companies.

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Source: Journal of Engineering


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