Patent ID: 7646213
Filing Date: 2010-01-12
Classification: H03K,H04L

Abstract:
1. A termination circuit fabricated on a semiconductor die along with an electronic device having an externally accessible terminal, the termination circuit comprising: a programmable on-die termination (“ODT”) circuit coupled to the externally accessible terminal, the programmable ODT circuit providing the externally accessible terminal with an impedance using the combination of a terminating resistor and a controllable impedance element having an impedance that is controlled by at least one programming signal received by the programmable ODT circuit; and a programming circuit operable to determine the approximate impedance of the terminating resistor and to provide the at least one programming signal to the ODT circuit so that the impedance provided by the combination of the terminating resistor and the controllable impedance element is substantially equal to a predetermined target impedance, the programming circuit comprising: a test resistor having impedance characteristics that substantially match the impedance characteristics of the terminating resistor; and a measurement circuit for measuring the impedance of the test resistor, the measurement circuit comprising: