A 3.3-V CMOS adaptive analog video line driver with low distortion performance

Abstract

An analog line driver for video applications is presented. Utilizing a class-AB error amplifier structure, the design achieved 1.2-V peak-to-peak output swing with better than 42-dB linearity for frequencies up to 5 MHz. An adaptive tuning scheme for output impedance matching using peak detection is used to provide uniform performance across line impedance variations. The circuit is designed in AMI 0.5-CMOS technology and has a tuning range of 70-180 with a power consumption of about 26.4 mW at 75load.

Automatic impedance control for chip-to-chip interconnections

“…Control of transistors is made in a digital way and voltage comparisons are the reference for the impedance value. In reference [3] impedance matching is made by controlling output impedance of line drivers. This is done by analog controlling of variable resistors at the power stage of the driver.…”

“…In this case, signal reflections traveling trough the line are present in either, driver to receiver or receiver to driver, directions. Unfortunately, it is difficult to achieve perfect matching due to the large process variations in the fabrication of interconnect lines and the length variations between them [3]. Moreover, temperature variations and external effects are also present.…”

An Adaptive Low Power Video Line Driver

“…In this work tuning circuit is also responsible to create the output impedance equal to appropriate value. If dimension of current mirrors of tuning module is set identical then the output impedance of the circuit can be written as following: Rout 2g18 (6) out 2n {g18 + gm28 } Increasing the transconductances of M17-18-28-29 results more accurate tuning process but greater transconductances reduce output impedance much lower than desirable value. Relation shows that quiescent current of output transistors is directly related to the output impedance of structure because lower quiescent current makes higher transconductances therefore circuit has lower output impedance.…”

“…An adaptive line driver [5] achieves approximately 50-dB linearity and 1.2-Vp-p also adapts between 35 and 85-Q load resistance. And adaptive line driver [6] achieves 1.5-Vp-p and better than 42-dB linearity also compensates output variations from 70 to 180-Q. Tuning module of all reported adaptive structures [3], [5], [6] have been implemented by using of variable resistors in source of transistors which configures output stage of class-AB structure.…”

“…And adaptive line driver [6] achieves 1.5-Vp-p and better than 42-dB linearity also compensates output variations from 70 to 180-Q. Tuning module of all reported adaptive structures [3], [5], [6] have been implemented by using of variable resistors in source of transistors which configures output stage of class-AB structure. Furthermore, control voltage of variable resistors is provided by capacitor based module.…”