Analog building blocks are
the fundamental elements for the transparent and flexible TFT
integration systems, such as flexible panels, bio-sensing
applications and electronic textiles. By integrating TFT-based
building blocks, the product costs and processing complexity could
be dramatically reduced. The so-called system-on-panel (SoP) or
heterogeneous electronics system could integrate multifunctional
circuits on a single chip. Consequently, it drives the demand of
TFT-based peripheral circuits, including amplifying circuits, DAC,
ADC converter and other feedback circuits. However, usually the TFT
based circuits are leak of complementary components and are less
stable compared with conventional CMOS circuit, which make the
circuit design more critical. Figure 1, 2 and 3
demonstrated simple TFT-based OPAMP circuit deign.
For Thin-film Transistor (TFT) based large area flexible sensors,
the high performance TFT-based Analog to Digital Converters (ADCs)
are needed to locally convert weak sensing signals to robust digital
signals, which realizes the weak sensing signals can travel through
long distance to other circuit blocks. For some ADC circuits,
Digital to Analog Converters DACs are also the essential components
which convert the digital signals back to analog signals. Generally,
TFT-based ADCs have three types of topology (Flash ADC, Sigma Delta
ADC and Successive Approximation ADC), and the resolution of analog
to digital conversion can be up to 6-bit.
Voltage and Current Sources:
Thin-film transistor based voltage and current sources are aimed to replace or reduce the complexity of the external electrical sources for thin-film circuit systems. However, current circuit topologies are not suitable for TFT due to stability and other issues. Current studies on novel material TFTs are pushing the technology towards better performance. And new circuit topologies are being designed to either use or compensate the particular properties of TFT to achieve a stable and even temperature independent electrical source.
Besides these, we are also working on the rest of Analog & Digital Building Blocks:
Ring Oscillator (RO), Mixer, Mux, DeMux, Filp-Flops, Anolog Filters (LPF, HPF, BPF), and so on.