Difference amplifier for digital-to-analog converter
AssigneeTexas Instruments Incorporated
InventorMark Allan Shill
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Abstract
An improved circuit is provided that buffers the output of a DAC while improving the bandwidth and linearity of the circuit. A DAC comprises an output signal of a switched DAC circuit coupled to an inverting node of an output buffer configured as a difference amplifier, while a non-inverting node of the difference amplifier is coupled to a fixed reference potential. As a result, the difference amplifier buffers the output of the switched DAC circuit while permitting the use of N-type input stages in the amplifier, which can enhance the bandwidth capability of the circuit.
Claims20
A digital-to-analog converter (DAC) for providing increased bandwidth and linearity, said DAC comprising:
- a switched sampling circuit configured for providing an output signal at an output terminal;
- and
- a difference amplifier configured for buffering said output signal of said switched sampling circuit, said difference amplifier having an inverting node, a non-inverting node, a feedback resistor, and an output node, said output terminal of said switched sampling circuit coupled to said inverting node, said inverting node being coupled through said feedback resistor to said output node, said non-inverting node being coupled to a first potential source.
An output buffer configured for buffering an output of a digital-to-analog converter, said output buffer being configured as a difference amplifier circuit and comprising:
- an inverting input terminal configured to receive an output signal from a switched DAC circuit;
- a non-inverting input terminal coupled to a fixed voltage potential;
- an output terminal;
- and
- a feedback resistor configured between said inverting node and said output terminal;
- and wherein said output buffer can facilitate increased bandwidth and linearity in a digital-to-analog converter.
A method for buffering the output of a digital-to-analog converter to facilitate increase bandwidth and linearity in the digital-to-analog converter, said method comprising the steps of:
- providing an output signal from a switched DAC circuit to an inverting node of a difference amplifier;
- providing a fixed voltage potential to a non-inverting node of said difference amplifier;
- and
- coupling an output of said difference amplifier through a feedback resistor to said inverting node of said difference amplifier.
Dependencies are inferred from the claim text.