In recent years, there is a growing interest in low-cost and high data rate mm-wave transceivers for high bandwidth applications such as wireless personal area networks (WPANs), radars, high definition media, and so on [1]. Among them are the 60 GHz oscillators for covering the worldwide union of bands from 57 GHz to 66 GHz has gained a lot of traction and investment. Designing at such high frequencies introduce a lot of challenges, especially the saturating Quality factor (Q) of the employed resonator elements (LC tank and varactors) [2], [3]. This is due to the high electrical and magnetic losses at the mm-wave range which results in reduced output power, restricted tuning range, and large phase noise. Such high-frequency oscillators are implemented as either fundamental-mode oscillators or harmonic-based oscillators (push-push, triple-push, etc). The above-mentioned drawbacks have been shown to be overcome, with the use of N-push harmonic oscillators which use identical fundamental oscillators connected in a ring or star topology to a common load [4]. By perfectly matching the oscillators in phase and power, we can achieve extended operating frequencies and eliminate the need for injection-locked frequency dividers in a typical mm-wave phase-locked loop.
To implement our 60 GHz triple push CMOS oscillator we will use a star network of three fundamental 20 GHz oscillators connected to a common load as shown in Fig. 1. The complete system is shown in Fig 2. An accumulation type varactor is used through a high-value resistor to tune the Voltage Control Oscillator (VCO) frequency. The value of This resistor is crucial for the stability of the system to ensure proper operation in triple push mode by canceling the even mode oscillations as shown in Fig. 2. For each VCO, we need to introduce two buffer stages to isolate their separate connections for 20 GHz and 60 GHz as shown in Fig. 3.
Jehan Nozer Taraporewalla
Divya Marichamy
[1] B. C ̧ atlı and M. M. Hella, “Systematic design of mmwave plls based on n-push oscillators,” in Proceedings of the 2010 ACM International Workshop on MmWave Communications: From Circuits to Networks, ser. mmCom ’10. New York, NY, USA: Association for Computing Machinery, 2010, p. 63–68. [Online]. Available: https://doi.org/10.1145/1859964.1859980
[2] B. C ̧ atli and M. M. Hella, “A 60 ghz CMOS combined mm-wave vco/divider with 10-ghz tuning range,” in IEEE Custom Integrated Circuits Conference, CICC 2009, San Jose, California, USA, 13-16 September, 2009, Proceedings. IEEE, 2009, pp. 665–668. [Online]. Available: https://doi.org/10.1109/CICC.2009.5280753
[3] B. C ̧ atli and M. M. Hella , “Triple-push operation for combined oscillation/divison functionality in millimeter-wave frequency synthesizers,” IEEE J. Solid State Circuits, vol. 45, no. 8, pp. 1575–1589, 2010. [Online]. Available: https://doi.org/10.1109/JSSC.2010.2049915
[4] B. C ̧ atli and M. M. Hella, “A 30-ghz triple-push oscillator on silicon for mm-wave applications,” in International Symposium on Circuits and Systems (ISCAS 2009), 24-17 May 2009, Taipei, Taiwan. IEEE, 2009, pp. 2037–2040. [Online]. Available: https://doi.org/10.1109/ISCAS.2009.5118193
To implement our 60 GHz triple push CMOS oscillator we will use a star network of three fundamental 20 GHz oscillators connected to a common load. The complete system is shown in Fig 2. An accumulation type varactor is used through a high-value resistor to tune the Voltage Control Oscillator (VCO) frequency. This resistors value is crucial for the stability of the system to ensures proper operation in triple push mode by cancelling the even mode oscillations as shown in Fig. 2. For each VCO, we need to introduce two buffer stages to isolate their separate connections for 20 GHz and 60 GHz as shown in Fig. 3.
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