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Why Use Temperature Variable Attenuators in Your Next RF and Microwave Circuit Design?

20 August 2020

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  • Why Use Temperature Variable Attenuators in Your Next RF and Microwave Circuit Design?

Temperature Variable Attenuators can be used in place of a standard chip attenuator to combine level setting and temperature compensation in a single chip design.

Temperature variable attenuators are used in RF and microwave circuits to compensate for changes in the amplitude response of the circuit that result from changes in temperature.  Passive devices such as filters, isolators and delay lines have temperature dependent amplitude responses, but the most common component requiring compensation is the amplifier.

Most RF and microwave solid state amplifiers are constructed using silicon bipolar or GaAs FET devices. As temperature increases, these amplifiers tend to decrease their gain which can result in unstable output and performance.

Temperature variable attenuators provide the opposite temperature characteristics of the amplifier, as the temperature rises the attenuation decreases. The amplifier’s loss of gain due to rising temperature can be compensated by including a temperature variable attenuator in series with the amplifier. The combination of the amplifier and temperature variable attenuator cancels out the temperature dependency of the components and can result in a stable output of gain and an increase in performance.

The diagram above is an example of stabilization between an Amplifier and Smiths Interconnect's Thermopad® Temperature Variable Attenuator.

Additional benefits of adding a temperature variable attenuator to your next RF or Microwave design are simplifying the design, increases reliability and cost savings. As technology advances and RF and Microwave designs become more complex, design engineers will be tasked to provide the necessary compensation to simplify the design, increase reliability and reduce cost.

In summary, decades of experience have positioned Smiths Interconnect well – both in designing and delivering active and passive connectivity solutions specifically engineered and optimized to mitigate the effects of heat, shock and vibration and to deliver unparalleled signal integrity, as well as reduced overall system size and weight that are essential in RF and Microwave applications.

Image of Thermopad®


The Thermopad® is a totally passive, surface mountable temperature variable attenuator. It requires no bias or control voltages and does not generate distortion. The Thermopad can be used in place of a standard chip attenuator to combine level setting or buffering and temperature compensation in a single chip design.

® are available in many size and package styles including surface mount, wire bondable and coaxial versions  We have versions that cover DC through 36GHz in frequency and 100 millwatts for 20 watts of power.


  • Frequency Range from DC to 36 GHz
  • Attenuation Values from 1 to 10dB
  • Wire Bondable Connections Available
  • Negative & Positive Coefficients of Attenuation Available
  • Tape and Reel Packaging Available
  • Space and Military Qualified

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