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I need to produce an extremely low noise SPDT switch. This switch will take two different inputs to a single 16 bit ADC. The inputs are 50 ohm BNC outputs from trans-impedance amplifiers. The amplifiers take a small current and convert them to 0-10V DC (they operate between 200 KHz and several MHz). This signal is then sampled at a rate of 1 MHz to 80 MHz, depending on application.

Currently I use the following component:

http://www.jfwindustries.com/products/50S_1313_12_SMA_Electro_mechanical_Switch_from_JFW_Industries-368-76.html

I tried to design a simple PCB using an OMRON relay. However, this introduced significant baseline voltage as well as noise (100-250 mV plus noise).

Does anyone have any ideas on how to design such a circuit? I tried some off-the-shelf RF switch ICs demo boards but nothing handles DC and/or they clipped at VCC = 3.3V and I need transmission to the full 10V range.

Is there something special about getting a board built at 50 Ohm controlled impedance? I used a single IC to power the relay and a 7805 regulator to provide 5V (the ground is shared with the SMA connectors and power supply).

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    \$\begingroup\$ why not use a load switch ic? super quick google search yielded this: ti.com/product/tps27082l. Also, please post a schematic; a sch will help in getting quicker more relevant answer \$\endgroup\$ – hassan789 Jun 15 '15 at 23:33
  • \$\begingroup\$ Try mini-circuits. \$\endgroup\$ – EM Fields Jun 16 '15 at 6:37
  • \$\begingroup\$ Analogue switches sound suitable. \$\endgroup\$ – Andy aka Jun 16 '15 at 7:31
  • \$\begingroup\$ DG series analog switch family should work for you. \$\endgroup\$ – Dwayne Reid Jun 16 '15 at 22:24
  • \$\begingroup\$ I added the schematics and layout. Also I realized that on this version the ground is shared with the 5V wall power supply. \$\endgroup\$ – bode Jun 16 '15 at 23:49

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