On-Panel Output Buffer With Offset Compensation Technique for Data Driver in LTPS Technology

Abstract

To overcome the offset voltage (V OS ) of output buffer due to large variation on characteristics of thin-film transistor (TFT) in low-temperature polysilicon (LTPS) technology, a class-B output buffer with offset compensation circuit for the data driver is presented in this paper. This proposed class-B output buffer can operate at 50-kHz operation frequency with a 2-8-V output swing for extended graphic array (XGA) application, and it has been demonstrated in 3-m LTPS technology. Using the offset compensation technique, the V OS of output buffer can be controlled within 100 mV under 2-to-8 V signal operation to achieve a high resolution and quality liquid crystal display (LCD) panel.

P‐52: High‐Gain Source Followers Driven by Corbino Oxide TFTs for Integrated Display Data Drivers

“…It can be seen that the offset voltage (Vin -Vout) varies with different bias voltage given that it is required that the voltage between a gate and a source in a TFT exceeds the threshold voltage of the TFT. However, this can be eliminated by gamma correction or by implementing the offset compensation technique [8], [13]. By utilizing the low-frequency, small-signal model on the source follower with an active load (the equivalent circuits are not shown here), the current equation for the output node is: Substituting vgs = Vin -Vout and solving (2),…”

“…They are needed to drive the load capacitance of the data bus in display driving circuits. Several designs for integrated output buffers in LTPS TFTs have been proposed for display applications [6]- [8]. Among these output buffer circuits, the source follower is considered an excellent candidate panel application for the system.…”

A Charge-Sensing-Capable Source Driver for TFT Array Testing in System-on-Panel Displays

“…Most TFT arrays are fabricated using the LTPS or a-Si technology. Compared to the mainstream CMOS technology, LTPS and a-Si TFT devices suffer low mobility and V t variations [12], [13], [14], [15]. In particular, LTPS process is prone to spatial V t variations while a-Si process is prone to temporal V t variations.…”

Design and implementation of capacitive sensor readout circuit on glass substrate for touch panel applications

“…The harmful effects of irregular grain boundaries, gateinsulator interface defects, and incomplete ion-doping activation in thin poly-silicon channels result in the variation on electrical characteristics of LTPS TFTs. Polysilicon TFTs suffer serious variation of device behavior, especially in mobility and threshold voltage, which are two important features in the realization of onpanel circuit integration [8], [9].…”