A distinctive connection method in cascaded RF/MW active device system achieving both stability and low gain loss is presented. Unlike traditional methods (isolator and attenuator), the proposed solution introduces an appropriate length of transmission line to change the input impedance at the out-band instable frequency point and uses a narrow-band termination to absorb the instable power without deteriorating in-band signal. Moreover, the reason that instability often occurs in the cascaded system is analysed with S-parameters， and it turns out to be a kind of out-band instability. And then the solution is verified by an adjustable circuit example whose insertion loss is below 0.3 dB.
2. Gray, P. and R. Meyer, Analysis and Design of Analog Integrated Circuit, John Wiley and Sons, 1993.
3. Kundert, K. S., The Designer’s Guide to SPICE and Spectre, Kluwer Academic Publishers, 1995.
4. Otegi, N., A. Anakabe, J. Pelaz, J. M. Collantes, and G. Soubercaze-Pun, "Experimental characterization of stability margins in microwave amplifiers," IEEE Trans. Microwave Theory and Techniques, Vol. 60, No. 12, 4145-4156, Dec. 2012.
doi:10.1109/TMTT.2012.2221736
5. Cripps, S. C., RF Power Amplifiers for Wireless Communications, 2nd Edition, Artech House Inc., Norwood MA, 2006.
6. Saad, P., C. Fager, H. Cao, H. Zirath, and K. Andersson, "Design of a highly efficient 2–4 GHz octave bandwidth GaN-HEMT power amplifier," IEEE Trans. Microwave Theory and Techniques, Vol. 58, No. 7, 1677-1685, Jul. 2010.
doi:10.1109/TMTT.2010.2049770
7. Jackson, R. W., "Rollett proviso in the stability of linear microwave circuits," IEEE Trans. Microwave Theory and Techniques, Vol. 54, No. 3, 993-1000, Mar. 2006.
doi:10.1109/TMTT.2006.869719
8. Davenport, Jr., W. B. and W. L. Root, Random Signals and Noise, McGraw-Hill, New York, 1958.
9. Pozar, D. M., Microwave Engineering, 3rd Edition, John Wiley & Sons Inc., 2005.
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