Sigma-delta modulator
AssigneeFreescale Semiconductor, Inc.
InventorMerit Y. Hong
Life of this patent
Estimating the term…
Abstract
An integrator circuit (110) is provided including an amplifier element (170) configured to receive an input signal at an input node, amplify the input signal, and provide an amplified input signal at an output node; a feedback capacitor element (175) connected between the output node and the input node; and a current matching circuit (120) connected to the output node, and configured to sense an output voltage of the amplifier element and to provide a supplemental current (IM) to the input node that is less than or equal to a feedback current (IF) charging the feedback capacitor element. This supplemental current is substantially equal and opposite in polarity to a feedback current when the output voltage satisfies a set criterion.
Claims20
A sigma-delta modulator, comprising:
- a first integrator for receiving an input voltage and providing a first integrating output voltage;
- a first feedforward element for converting the first integrating output voltage to a first feedforward signal;
- a comparator for comparing the first feedforward signal to a comparator threshold value to produce a comparator output value;
- a first feedback element for providing the comparator output value to the first integrator;
- and
- a first matching circuit for providing a first matching current to an output node of the first integrator when the first output voltage rises above a first voltage maximum value or falls below a first voltage minimum value.
A method of sigma-delta modulation, comprising:
- receiving an input voltage;
- modifying the input voltage based on a feedback value;
- integrating the modified input voltage to provide a first output voltage;
- converting the first output voltage to a first feed forward signal;
- comparing the first feed forward signal to a threshold value to produce the feedback value;
- determining whether the first output voltage has risen above a first voltage maximum value or fallen below a first voltage minimum value;
- and
- providing a first matching current to adjust the first output voltage if the first output voltage has risen above the first voltage maximum value or fallen below the first voltage minimum value.
Dependencies are inferred from the claim text.