Low variation voltage output differential for differential drivers
View Patent ↗The methods and systems presented herein provide an improved means of correcting the variation of Voltage Output Differential (VOD) in differential drivers. In some embodiments, a high-precision reference voltage is generated not only based on a desired VOD, but also by monitoring the Voltage Common Mode (VCM) in a differential driver. In some embodiments, the VOD is then compared with the high-precision reference voltage to correct the output current. The result is a low-variation output voltage.
1. A differential driver system comprising:
a reference voltage circuit that generates a reference voltage determined from a desired output voltage based on a common-mode voltage of the differential driver system;
a sampler voltage circuit that generates a sample voltage by monitoring an output voltage across two terminals of an external load resistor; and
a compensation circuit for controlling the output voltage at least in part by generating a compensation current based at least in part on the reference voltage and the sample voltage.
2. The differential driver system according to claim 1 , wherein the reference voltage is equal to the sum of the common-mode voltage and one-half of the desired output voltage.
3. The differential driver system according to claim 1 , wherein the reference voltage is equal to the common-mode voltage minus one-half of the desired output voltage.
4. The differential driver system according to claim 1 , wherein the sample voltage is equal to the sum of the common-mode voltage of the differential driver system and one-half of the output voltage.
5. The differential driver system according to claim 1 , wherein the sample voltage is equal to common-mode voltage of the differential driver system minus one-half of the output voltage.
6. The differential driver system according to claim 1 , wherein the compensation circuit compares the reference voltage with the sample voltage and sets the compensation current such that the output voltage is equal to a desired value.
7. A Multipoint Low Voltage Differential Signaling (MLVDS) system comprising:
a reference voltage circuit that generates a reference voltage determined from a desired output voltage based on a common-mode voltage of the MLVDS system;
a sampler voltage circuit that generates a sample voltage by monitoring an output voltage across two terminals of an external load resistor; and
a compensation circuit for controlling the output voltage at least in part by generating a compensation current based at least in part on the reference voltage and the sample voltage.
8. The MLVDS system according to claim 7 , wherein the reference voltage is equal to the sum of the common-mode voltage and one-half of the desired output voltage.
9. The MLVDS system according to claim 7 , wherein the reference voltage is equal to the common-mode voltage minus one-half of the desired output voltage.
10. The MLVDS system according to claim 7 , wherein the sample voltage is equal to the sum of the common-mode voltage of the MLVDS system and one-half of the output voltage.
11. The MLVDS system according to claim 7 , wherein the sample voltage is equal to the common-mode voltage of the MLVDS system minus one-half of the output voltage.
12. The MLVDS system according to claim 7 , wherein the compensation circuit compares the reference voltage with the sample voltage and sets the compensation current such that the output voltage is equal to a desired value.
13. A method of driving a differential line, comprising:
generating a reference voltage determined from a desired output voltage based on a common-mode voltage of the differential line;
generating a sample voltage by monitoring an output voltage across two terminals of an external load resistor; and
controlling the output voltage at least in part by generating a compensation current based at least in part on the reference voltage and the sample voltage.
14. The method according to claim 13 , wherein the reference voltage is equal to the sum of the common-mode voltage and one-half of the desired output voltage.
15. The method according to claim 13 , wherein the reference voltage is equal to the common-mode voltage minus one-half of the desired output voltage.
16. The method according to claim 13 , wherein the sample voltage is equal to the sum of the common-mode voltage of the deferential line and one-half of the output voltage.
17. The method to claim 13 , wherein the sample voltage is equal to the common-mode voltage of the deferential line minus one-half of the output voltage.
18. The method according to claim 13 , wherein the controlling step comprises comparing the reference voltage with the sample voltage and setting the compensation current such that the output voltage is equal to a desired value.