Turner's thesis:

The second recommendation for future work is to duplicate and extend this work in SiGe. InP was used in this thesis, because one of the aims of the TFAST project was to push the development of InP technologies. There is interest in developing InP technologies because their superior BVCEO compared to SiGe is expected to result in high performance mixed-signal circuits. Despite the lower BVCEO, SiGe technology has some advantages in other areas that could be exploited. First of all, since the SiGe process is built on top of a CMOS process, PMOS and NMOS transistors are available. An NMOS transistor could be used as a high impedance current source with a lower voltage drop than the current sources in this thesis. The high impedance of the NMOS source would be an improvement over the low impedance resistor-only current sources that had a low voltage drop. This would allow for a reduction in power consumption. Secondly, the SiGe process has copper interconnects. The InP process is currently limited to aluminum interconnects with wide pitches compared to the copper interconnects in SiGe. Smaller interconnects would allow for reduced parasitic capacitances and improve the relative performance. Finally, the SiGe process in more manufacturable than InP, so yields and consistency between fabrication runs would be improved. Since SiGe is more manufacturable than InP, it also costs less. SiGe is rapidly developing due to interest in RF technologies, so at some point in the future, the performance of SiGe devices may exceed the performance of InP devices. Some of the designs in this thesis could be ported to a SiGe technology, to compare the mixed-signal performance of SiGe vs. InP. The designs could be modified for reduced power by using NMOS current sources, and the differences in layout parasitic capacitance could be explored.

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从前对于SiGe和RF CMOS没怎么关注，只是在读GaAs InP的paper的时候顺便了解一些。想当然地以为，SiGe和RF CMOS单拼性能是搞不过III-V的。可是，今天见了一大堆让我大吃一惊的东西，比如CMOS的W-band（甚至是超过100GHz的）RFIC，包括LNA，Transceiver，LNA，Mod/DeMod等等；410GHz CMOS phsh-push VCO；35Gsps 4-bit Flash ADC based on BiCMOS等等。



坐井观天，鼠目寸光。

不过，SiGe和RF CMOS在超高速和超高频电子方面有这样的作为，主要还是得益于先进的CMOS制程，基本上都是65nm和45nm尺寸；而III-V的尺寸还在500nm左右，最先进的InP HBT，其Ft已经超过了1.2THz。除此之外，他们还有一些别的硬伤，比如其饱受诟病的低击穿特性，使得他们在功率应用方面难有作为；再比如没有半绝缘衬底，从而超高速混合信号应用中串扰严重；还比如......

总之，还是应该站得高一些，看得远一些。