يك ساختار جديد براي كليد تك ورودي- دو خروجي مبتني بر ‌ديود پين جهت كاربرد در فرستنده و گيرنده‌هاي باند ريزموج

A new SPDT switch based on PIN diode for transceiver applications in microwave band

ﭼﮑﯿﺪه: ﮐﻠﯿﺪﻫﺎي ﺗﮏ وردي-دو ﺧﺮوﺟﯽ در ﺳﯿﺴﺘﻢﻫﺎي ﺑﯽﺳﯿﻢ، ﻧﻈﯿﺮ واﯾﻤﮑﺲ ﺑﻪ ﻋﻨﻮان داﭘﻠﮑﺴﺮ ﺑﮑﺎر ﻣﯽروﻧﺪ و ﺗﻐﯿﯿﺮ از ﺣﺎﻟﺖ ارﺳﺎل ﺑﻪ ﺣﺎﻟﺖ درﯾﺎﻓﺖ و ﺑﺮﻋﮑﺲ را اﻧﺠﺎم ﻣﯽ دﻫﻨﺪ. در ﮐﻠﯿﺪﻫﺎي ﺗﮏ ورودي- دو ﺧﺮوﺟﯽ رﯾﺰﻣﻮج، ﻣﯽﺗﻮان از ﭘﯿﻦ دﯾﻮدﻫﺎ ﯾﺎ ﺗﺮاﻧﺰﯾﺴﺘﻮرﻫﺎي اﺛﺮ ﻣﯿﺪاﻧﯽ ﺑﺮاي ﮐﻠﯿﺪزﻧﯽ اﺳﺘﻔﺎده ﻧﻤﻮد. اﻣﺎ دﯾﻮدﻫﺎي ﭘﯿﻦ ﻗﺎﺑﻠﯿﺖ ﮐﻨﺘﺮل ﺗﻮان ﺑﯿﺶ ﺗﺮي را دارﻧﺪ و ﺑﺮاي ﮐﺎرﺑﺮد ﺑﻪ ﻋﻨﻮان داﭘﻠﮑﺴﺮ ﻣﻨﺎﺳﺐ ﻫﺴﺘﻨﺪ. ﺗﻠﻔﺎت ﻋﺒﻮرﮐﻢ، ﺟﺪاﺳﺎزي ﺑﺎﻻ و ﺳﺮﻋﺖ ﮐﻠﯿﺪزﻧﯽ از ﻣﺴﺎﺋﻞ اﺻﻠﯽ در ﻃﺮاﺣﯽ ﮐﻠﯿﺪﻫﺎ اﺳﺖ. ﺑﻪﻃﻮرﮐﻠﯽ، ﺑﺮاي ﮐﺎرﺑﺮدﻫﺎي ﺑﺎﻻﺗﺮ از 3 ﮔﯿﮕﺎﻫﺮﺗﺰ، دﺳﺖﯾﺎﺑﯽ ﺑﻪ ﺟﺪاﺳﺎزي ﺑﺎﻻي 30 دﺳﯽﺑﻞ ﮐﺎر ﺑﺴﯿﺎر دﺷﻮاري اﺳﺖ، زﯾﺮا ﺳﺎﺧﺘﺎر ﮐﻠﯿﺪ ﺗﮏ ورودي-دو ﺧﺮوﺟﯽ ﻣﻌﻤﻮﻟﯽ ﻧﻤﯽﺗﻮاﻧﺪ ﻣﺸﮑﻞ ﺿﺮﯾﺐ ﺧﻮداﻟﻘﺎﯾﯽ اﻧﮕﻠﯽ ﺑﺰرگ ﻧﺎﺷﯽ از ﺑﺴﺘﻪﺑﻨﺪي را در ﺑﺴﺎﻣﺪﻫﺎي ﺑﺎﻻ ﺣﻞ ﮐﻨﺪ. در اﯾﻦ ﻣﻘﺎﻟﻪ، ﺑﺮاي ﺣﻞ ﻣﺸﮑﻞ ﻓﻮق ﺳﺎﺧﺘﺎر ﺟﺪﯾﺪي اراﺋﻪ ﻣﯽ ﮔﺮدد ﮐﻪ در آن از ﯾﮏ ﺗﺸﺪﯾﺪﮐﻨﻨﺪه رﯾﺰﻧﻮار ﻣﻮازي ﺑﺎ دﯾﻮد ﭘﯿﻦ اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. اﯾﻦ ﺗﺸﺪﯾﺪﮐﻨﻨﺪه، ﺑﻪ ﻫﻤﺮاه ﯾﮏ ﺗﺸﺪﯾﺪﮐﻨﻨﺪه رﯾﺰﻧﻮار ﺳﺮي اﺛﺮ ﺳﻠﻔﯽ ﻧﺎﺷﯽ از ﺑﺴﺘﻪ ﺑﻨﺪي دﯾﻮد را در ﺣﺎﻟﺖ روﺷﻦ ﺑﻮدن دﯾﻮد و اﺛﺮ ﺧﺎزﻧﯽ ذاﺗﯽ دﯾﻮد را در ﺣﺎﻟﺖ ﺧﺎﻣﻮش ﺑﻮدن آن از ﺑﯿﻦ ﻣﯽ ﺑﺮد و ﺑﻪ اﯾﻦ ﺗﺮﺗﯿﺐ ﺑﺎﻋﺚ اﻓﺰاﯾﺶ ﺟﺪاﺳﺎزي ﻣﯽ ﺷﻮد. ﺑﻪ ﻋﻼوه، در ﻃﺮح ﭘﯿﺸﻨﻬﺎدي ﻫﯿﭻ ﯾﮏ از دﯾﻮدﻫﺎ در ﻣﺴﯿﺮ ﺳﯿﮕﻨﺎل ﻗﺮار ﻧﺪارﻧﺪ و ﺑﻪ ﻫﻤﯿﻦ دﻟﯿﻞ، ﺗﻠﻔﺎت ﻋﺒﻮري ﺑﺴﯿﺎر ﭘﺎﯾﯿﻦ اﺳﺖ. در ﻃﺮاﺣﯽ ﮐﻠﯿﺪ ﭘﯿﺸﻨﻬﺎدي از ﭘﯿﻦدﯾﻮد ﺑﺎ ﺷﻤﺎره ﻗﻄﻌﻪ SMP1340 اﺳﺘﻔﺎده ﺷﺪهاﺳﺖ ﮐﻪ ﺳﺮﻋﺖ ﮐﻠﯿﺪزﻧﯽ ﺑﺴﯿﺎر ﺑﺎﻻﯾﯽ دارد. ﻫﻤﭽﻨﯿﻦ اﯾﻦ ﭘﯿﻦدﯾﻮد ﻧﺴﺒﺖ ﺑﻪ دﯾﮕﺮ ﭘﯿﻦدﯾﻮدﻫﺎ از ﺧﺎزن ﭘﯿﻮﻧﺪ و ﻣﻘﺎوﻣﺖ ﻫﺪاﯾﺘﯽ ﮐﻮﭼﮏﺗﺮي ﺑﺮﺧﻮردار اﺳﺖ. ﺑﺎ اﺳﺘﻔﺎده از ﺗﺤﻠﯿﻞ رﯾﺎﺿﯽ ﻋﻤﻠﮑﺮد ﮐﻠﯿﺪ، رواﺑﻂ رﯾﺎﺿﯽ ﻃﺮاﺣﯽ ﺑﻪ دﺳﺖ آﻣﺪه اﺳﺖ و ﺟﻬﺖ اﺛﺒﺎت ﺻﺤﺖ ﺗﺤﻠﯿﻞ و ﻋﻤﻠﮑﺮد ﻃﺮح ﭘﯿﺸﻨﻬﺎدي، ﮐﻠﯿﺪ ﻃﺮاﺣﯽ ﺷﺪه در ﻧﺮم اﻓﺰار ADS ﺷﺒﯿﻪﺳﺎزي ﺷﺪهاﺳﺖ. اﯾﻦ ﺷﺒﯿﻪ ﺳﺎزي اﺑﺘﺪا ﺑﺼﻮرت ﺷﻤﺎﺗﯿﮏ و ﺳﭙﺲ ﺧﻄﻮط اﻧﺘﻘﺎل ﺑﺼﻮرت ﭼﯿﺪﻣﺎن ﺑﺮ روي زﯾﺮﻻﯾﻪ و ﺑﺎ اﺳﺘﻔﺎده از ﻗﺎﺑﻠﯿﺖ EM_Cosim ﻧﺮم اﻓﺰار ADS اﻧﺠﺎم ﺷﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ ﺷﺒﯿﻪ ﺳﺎزي، ﺟﺪاﺳﺎزي ﺑﯿﺶ از 50 دﺳﯽﺑﻞ و ﺗﻠﻔﺎت ﻋﺒﻮر ﮐﻤﺘﺮ از 0/2 دﺳﯽﺑﻞ را ﻓﻘﻂ ﺑﺎ اﺳﺘﻔﺎده از ﭼﻬﺎر ﻋﺪد دﯾﻮد ﭘﯿﻦ ﻧﺸﺎن ﻣﯽدﻫﺪ.

SPDT switches are used as duplexer in wireless systems, as WIMAX, to switch between transmit and receive states. Microwave SPDT switches may be designed using FET’s or PIN diodes. However, PIN diode is suitable for duplexer applications due to its high power handling capability. I general, in frequencies higher than 3 GHz, isolation better than 30 dB is a challenge. This is due to the parasitic inductance of PIN diode. In this paper, we propose a new structure for SDPT PIN diode switch to overcome this challenge. In the proposed structure a micro-strip line is adopted parallel to the diode. This line, in conjunction with another micro-strip line that is in series with the diode, eliminates the diode inductance in on-state and the diode capacitance in off-state, and hence improves both of isolation and insertion loss. The proposed structure has been analyzed mathematically and analytic equations have been derived to design the proposed switch. Finally, simulation results have been used to validate the performance of the switch. Simulations are performed using SMP1340 PIN diode and the model presented by the diode manufacturer. The simulations are in ADS and EM and EM_Cosim simulators are used to simulate the switch layout and include the layout effects accurately. Simulation results show more than 50dB isolation and less than 0.2dB insertion loss.