On-Wafer Microwave De-Embedding Techniques

Wireless communication technology has kept evolving into higher frequency regime to take advantage of wider data bandwidth and higher speed performance. Successful RF circuit design requires accurate characterization of on-chip devices. This greatly relies on robust de-embedding technique to completely remove surrounding parasitics of pad and interconnects that connect device to measurement probes. Complex interaction of fixture parasitic at high frequency has imposed extreme challenges to de-embedding particularly for lossy complementary metal oxide semiconductor (CMOS) device. A generalized network de-embedding technique that avoids any inaccurate lumped and transmission line assumptions on the pad and interconnects of the test structure is presented. The de-embedding strategy has been validated by producing negligible de-embedding error (<−50 dB) on the insertion loss of the zero-length THRU device. It demonstrates better accuracy than existing de-embedding techniques that are based on lumped pad assumption. For transistor characterization, the de-embedding reference plane could be further shifted to the metal fingers with additional Finger OPEN-SHORT structures. The resulted de-embedded RF parameters of CMOS transistor show good scalability across geometries and negligible frequency dependency of less than 3% for up to 100 GHz. The results reveal the importance of accounting for the parasitic effect of metal fingers for transistor characterization

MEMS-BASED OSCILLATORS: A REVIEW

ABSTRACT: This paper presents an overview of microelectromechanical (MEMS) based oscillators. The accuracy and stability of the reference frequency will normally limit the performance of most wireless communication systems. MEMS technology is the technology of choice due to its compatibility to silicon, leading to integration with circuits and lowering power consumption. MEMS based oscillators also provide the potential of a fully integrated transceiver. The most commonly used topology for MEMS based oscillators are pierce oscillator circuit topology and TIA circuit topology. Both topologies result in very competitive output in terms of phase noise and power consumption.  They can be used for either higher or lower Rx. The major difference between both topologies is the number of transistors used. TIA circuit used more number of transistor compare to pierce circuit. Thus design complexity of the TIA is higher. Pierce circuit is simpler, provide straightforward biasing and easier to design. The highly integratable of MEMS-based oscillators have made them much needed in future multiband wireless system. So that future wireless systems are able to function globally without any problem. ABSTRAK: Kertas kerja ini membentangkan gambaran keseluruhan mikroelektromekanikal (MEMS) berdasarkan pengayun.  Ketepatan dan kestabilan frekuensi rujukan sering membataskan perlaksanaan kebanyakan sistem komunikasi tanpa wayar. Teknologi MEMS merupakan teknologi pilihan memandangkan ia serasi dengan silikon; membolehkan integrasi dengan litar dan penggunaan tenaga yang rendah.  Pengayun berdasarkan MEMS juga  berpotensi sebagai integrasi penuh penghantar-terima. Topologi yang sering digunakan untuk pengayun berdasarkan MEMS adalah topologi litar pengayun pencantas dan topologi litar TIA.  Keputusan bagi kedua-dua topologi adalah amat kompetitif dari segi fasa bunyi dan penggunaan tenaga. Ia boleh digunakan untuk meninggikan atau merendahkan Rx. Perbezaan utama di antara kedua-dua topologi adalah bilangan transistor yang digunakan. Litar TIA menggunakan bilangan transistor yang lebih daripada litar pencantas.  Maka, rekaan TIA adalah lebih rumit.  Litar pencantas adalah lebih ringkas, memberikan pincangan yang jelas dan rekabentuk yang mudah. Pengayun berdasarkan MEMS amat bersepadu menjadikan ia sesuai sebagai sistem tanpa wayar berbilang jalur masa depan.  Jesteru sistem tanpa wayar dapat berfungsi pada peringkat global tanpa sebarang kesulitan