Search for impedance calibration

摘要

A non-volatile storage system includes an impedance code calibration circuit. The device has a first variable impedance circuit and a second variable impedance circuit coupled to a calibration node. The device has a control circuit configured to access a previous impedance code for a previous impedance calibration and to divide the previous impedance code into a main impedance code and a remainder impedance code. The control circuit is configured to perform a search for a new impedance code starting with the main impedance code applied to the first variable impedance circuit while maintaining the remainder impedance code to the second variable impedance circuit. The control circuit is configured to add the final impedance code for the first variable impedance circuit with the remainder impedance code to produce a new impedance code for the impedance calibration.

主权项

1. A device comprising:
a calibration node; a variable impedance circuit coupled to the calibration node, wherein the variable impedance circuit comprises first variable impedance elements and second variable impedance elements; and a control circuit coupled to the variable impedance circuit, wherein the control circuit is configured to:
divide a previous impedance code into a first impedance code and a second impedance code;apply the first impedance code to the first variable impedance elements;apply the second impedance code to the second variable impedance elements;calibrate an impedance of the variable impedance circuit with respect to the calibration node, wherein the control circuit is configured to perform a search starting with the first impedance code applied to the first variable impedance elements while maintaining the second impedance code to the second variable impedance elements, wherein the search results in a final impedance code for the first variable impedance elements; andadd the final impedance code with the second impedance code to produce a new impedance code for the impedance calibration of the variable impedance circuit with respect to the calibration node.