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A trouble with a system of several ADRF5020

Question asked by fwd on Jul 28, 2017
Latest reply on Mar 5, 2018 by nutbuster

  Hello.
   I have a trouble using four ADRF5020 switches for constructing an antenna switch with two inputs and two outputs (like HMC427ALP3E) in the band 8-18 GHz.
   The problem appears when I switch on the system as consistent with biasing-up procedure. Sometimes it happens when I power up VDD and VSS and sometimes when I power up the digital control input "CTRL" ("EN" is set to GND initially). This process causes damage of one or more ADRF5020 which appears in short-circuit of VDD or CTRL circuits to each other or to GND so I guess it is a damage of internal interface schematic diodes.
   The system can work initially for some time properly but later damages. I have two grounded sources +5V and -2.5V. There are blocking capacitors on RF-outputs of the system but no blocking capacitors between ADRF5020 swithes.
   So I have several questions:
 1. In ADRF5020 datasheet external resistors 0 Ohm are mentioned in digital circuits of Evaluation Board. I have no resistors in my circuitry. May be the solution of the problem is in placing resistors of for example 100 Ohm like in HMC547ALC switch?
2. May the biasing-up procedure be disturbed by applying RF-signal from the antenna before powering up VDD, VSS and CTRL pins? (However the problem appears even with unconnected RF-pins) Can the input signal of for example 0dBm be applied before powering up VDD, VSS and CTRL pins?
3. Cab blocking capacitors between ADRF5020 swithes help?
4. Can the use of HMC547ALC switch in organazing such a scheme of several chips be more reliable?

Thank you.

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