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I have some HMC545AETR straight from the packet. They all have 2 Ohm between RFC and RF1 and RF2 regardless of 5V control signals on A and B. Any ideas?

I want to use the HMC545 to switch an 80MHz RF signal at about 2Vpp on/off. I have replicated the circuit with the 74HC04 (5V supply) as shown in the data sheet, connecting RF input to RF1 and taking output from RFC, all on 50 ohm lines. However, the switch seems to be a short circuit regardless of the state of the control signals, which I have checked are getting to the pins 4 & 6. Subsequently, I took a device straight from the packet and found that pin 5 to 1 and pin 5 to 3 , are both 2 Ohm. I have replaced all devices with no luck. Any ideas?


When the part is unbiased, both RFC-RF1 and RFC-RF2 paths have same resistance of 2ohm as you correctly measured.

Can you please send your circuit schematic? Do you have dc blocking capacitors at all RF pins?


  • Hi,

    The circuit was exactly the one shown in the data sheet, with the same components.

    We checked the power and control pins were all at the logic levels according to the truth table.

    We dropped the part and now use an NXP SA630, which works as expected, so the problem no longer matters to us.


    David Thomson

    Staff Electronics Engineer

    Coherent Inc.

    p. +44(0)141 945 8193

    Acre Drive, Glasgow , Scotland G20 0XA<>

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