Method and circuit for regulating loads of dynamic self-adaptation terminal

Abstract

The invention discloses a method for regulating loads of a dynamic self-adaptation terminal, and is characterized in that: an optimal trimming parameter is obtained by comparing an on-chip terminal impedance with a numerical value of a band gap reference circuit according to a self-adaptation control mechanism, the parameter implements feedback control on the terminal by means of an output control circuit; the invention uses on-chip resources to save costs; the terminal is isolated from the regulation circuit and has excellent dynamic characteristics; temperature characteristics can be better achieved by employing a regulation way of a resistance array than that by employing a transistor array as equivalent resistance; compared with laser trimming, the invention is in no need of high expenditure; compared with external reference resistance, the invention saves IO pins and requires no external device; higher resistance regulation accuracy is realized; by utilizing high matching property of CMOS process resistance relative values, the invention accomplishes the separation of the regulation circuit from the terminal load circuit to reduce adverse influence brought therefrom.

Description

technical field [0001] The invention relates to adjusting the terminal load by utilizing the internal bandgap reference and reference current, in particular to a dynamic self-adaptive terminal load adjustment method and circuit. Background technique [0002] For high-speed data transmission systems, impedance mismatch will cause signal reflection and affect signal quality, so the impedance matching between the sending end and the receiving end is very important. However, the deviation of process manufacturing exists objectively, which requires proper adjustment of the error caused by process manufacturing. compensation. [0003] Commonly used compensation methods include laser trimming, parallel transistors as equivalent compensation resistors, or off-chip reference resistors. Laser trimming is to position a beam of focused coherent light on the workpiece under the control of a microcomputer, so that the film layer of the workpiece to be adjusted is vaporized and removed to...

AI Technical Summary

Problems solved by technology

Laser trimming is to position a beam of focused coherent light on the workpiece under the control of a microcomputer, so that the film layer of the workpiece to be adjusted is vaporized and removed to achieve the specified parameters or resistance values. The disadvantage is that the cost is too high; the use of transistors for compensation The method mainly uses the transistor as an equivalent compensation resistor, the disadvantage is that the temperature characteristic is poor, and the equivalent resistance will change with the working environment (working voltage / temperature, etc.); the off-chip reference method mainly uses an external precise resistor as a reference To adjust the internal termination resistor, the disadvantage is that an additional output pin is required, and its accuracy depends on the accuracy of the external resistor

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