Analog-to-Digital Converter Using Digital Output as Dither
AssigneeAnalog Devices, Inc.
InventorJohn A. Geen
Life of this patent
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Abstract
An analog-to-digital converter includes a delta circuit, a sigma circuit, and a quantizer circuit and further includes a feedback circuit that modulates a reference voltage provided to the quantizer circuit based on the quantizer circuit output. Modulation of the quantizer reference voltage dithers the quantizer circuit to effectively reduce or avoid lock bands. The analog-to-digital converter may be used in combination with a microelectromechanical (MEMS) device such as a gyroscope, an accelerometer, or a pressure sensor.
Claims19
Apparatus comprising an analog-to-digital converter for converting an analog input signal to a digital output signal, the converter comprising:
- a. a delta circuit configured to produce a delta output signal based on the analog input signal and an analog feedback signal derived from the digital output signal;
- b. a sigma circuit configured to integrate the delta output signal to form a sigma output signal;
- c. a quantizer circuit configured to produce the digital output signal based on the sigma output signal and a reference signal;
- and
- d. a feedback circuit configured to modulate the reference signal based on the digital output signal.
A method for dithering an analog-to-digital converter apparatus, the apparatus including a quantizer for comparing a quantizer input voltage to a reference voltage, the quantizer having an output voltage, the method comprising:
- a. storing the quantizer output voltage in a digital memory;
- and
- b. varying the reference voltage based on the stored output voltage.
Dependencies are inferred from the claim text.