Electronic-Photonic Integrated Digital-to-Analogue Converter

在EPIDAC项目中，我们希望开发新的概念，以大规模提高数模转换器（dac）的性能。改进是通过实现位路径、位路径的组合、时间交错和光域时钟来实现的。我们解决的问题是，例如，由于线性和电子速度边界在现代规模化硅工艺中，dac的性能不能再得到很大的提高。电DAC的性能受到带宽问题的限制，因为例如，对于位生成，必须在输出处组合大量路径（例如，分段6位DAC的17个单元），从而大大增加了电容寄生。如果在光域中组合位路径，则在光电二极管后只需要一个简单的单路跨阻放大器（TIA）即可反变换到电子域。因此，更高的带宽是可能的。此外，与电气方法相比，交错可以以更低的损耗和更高的精度实现。电子dac的分辨率受到时序失调的限制。通过使用外部馈电锁模激光时钟信号，其抖动值远低于电振荡器，可以减少不对准，从而提高分辨率。我们的概念性预研究表明，使用我们的电光方法，在80 GHz的带宽下应该有可能实现7个有效位的分辨率。与目前的技术水平相比，这将使分辨率增加4倍，带宽增加2倍，从而将相关的性能数字提高8倍。这将为下一代通信系统、测量设备和任意波形发生器铺平道路。对于器件实现和电光集成，我们采用IHP的EPIC SiGe SG25H4技术作为基础，该技术具有光学元件库和最大振荡频率为220 GHz的BiCMOS晶体管。我们的主要任务包括：光学辅助dac的系统建模、设计和优化，包括理论方面；开发、优化和硬件实现所需的集成光学元件（如光电探测器、分段调制器、耦合器和波导）和电路（如tia、调制器驱动器、校准电路，并取决于架构DAC子核）；而光电协整的关键模块。EPIDAC结合了德累斯顿工业大学的Frank Ellinger（年龄≥28岁）在高频电路设计和通信方面的互补能力，以及IHP的Lars Zimmermann（年龄≥20岁）在高速光子学和电光集成方面的互补能力。

In the EPIDAC project, we want to develop novel concepts, which massively improve the performance of digital-to-analogue converters (DACs). The improvement is enabled by implementing the bit paths, the combination of the bit paths, the time-interleaving, and/or the clock in the optical domain. We tackle the issue that e.g. due to linearity and electron velocity boundaries in modern scaled silicon processes, the performances of DACs can not be improved much anymore. The performance of electrical DACs is limited by bandwidth issues, since e.g. for the bit generation, a high numberof paths (e.g. 17 cells for a segmented 6-bit DAC) have to be combined at the output, thereby massively increasing the capacitive parasitics. If the bit paths are combined in the optical domain, we only need a simple one-path transimpedance amplifier (TIA) after the photo diode for the back-transformation into the electronic domain. Hence, higher bandwidth is possible. Moreover, compared to electrical approaches, interleaving can be implemented with lower losses and higher accuracy. The resolution of electrical DACs is limited by timing misalignments. By using externally fed mode-locked laser clock signals with jitter values much lower than what can be achieved with electrical oscillators, the misalignment can be reduced and thereby the resolution increased. Our conceptual pre-studies show that with our electro-optical approach it should be possible to achieve a resolution of 7 effective bits at a bandwidth of 80 GHz. Compared to the state of the art this would increase the resolution by a factor of 4 and the bandwidth by a factor of 2, thereby improving the associated figure of merit by a factor of 8. This will e.g. pave the way for next generation communication systems, measurement devices, and arbitrary waveform generators. For the device realization and electro-optical integration, we apply as basis the EPIC SiGe SG25H4 technology of IHP featuring e.g. a library of optical components as well as BiCMOS transistors with 220 GHz maximum frequency of oscillation. Our key tasks include: System modelling, design and optimisation of optically-assisted DACs including theoretical aspects; development, optimisation and hardware realisation of the required integrated optical components (e.g. photo detectors, segmented modulators, couplers and waveguides) and electrical circuits (e.g. TIAs, modulator drivers, calibration circuits, and depending on the architecture DAC sub-cores); and electro-optical co-integration of the key blocks. EPIDAC combines the complementary competences of Frank Ellinger (h ≥ 28) of TU Dresden in high-frequency circuit design and communications and Lars Zimmermann (h ≥ 20) of IHP in high-speed photonics and electrical-optical integration.