How To Design a Phase Shifter

A phase shifter is a device that is utilized in adjusting the phase of a radio frequency transmission.  This is essentially a microwave network apparatus, which allows manipulation of radio signals.  There are two types of phase shifters.  These are the fixed phase, also known as the digital phase shifters, and the variable types which are usually analog.  Designing this may require you to have enough background on electronics and radio communications.  This is because, in order to make an accurate signal production, some mathematical calculations have to be made.  However, the construction of the device itself is not difficult to do.

  1. Using a piece of a paper, a pen, and a calculator, draw a schematic diagram that should define the design you wish to have.  The schematic diagram is actually the phase circuit design.  Use your calculator in making accurate computations so that you will be able to get the desired signal results.
  2. Determine the phase calculation.  This can be computed from the disparity between the reference arm’s electrical length and delay arm.  Any transmission line has a phase that is equal to the length multiplied by its own constant of propagation.  You may use the most common means for computation other than radians, which is in electrical degrees.
  3. For a basic switch-line phase shift, you will only need a pair of single pole and double throw or SPDT switches.  These may be done in many methods with the use of diode, FET or micro-electromechanical system switches.  The sum of the distances of the switches must be beyond 20 dB.  Otherwise, a ripple will be created in the frequency phase response and in the amplitude.
  4. You must make sure that the technology of the switch you are using is suitable to the desired frequency band. In microwave integrated circuit or MIC, PIN diodes are utilized as switches.  On the other hand, FETS are used for those in monolithic microwave integrated circuit design.
  5. Diodes are recommended often for use in a level shifter since it is a better element for switching than the FET.  However, if your design is a monolithic circuit, then you may use the FET.  This can rid itself of its off-state capacitance once it reaches extremely high frequencies by employing shunt induction.

When the phase shifter design is done and realized through actual construction, you can begin to test it.  You can do this by trying to adjust the angle of the transmission phase of a network.  You will know if your device actually works if it gives off very little loss in insertion.  In all states of the phase, it should also have an equal degree of amplification. If you notice that there are losses, what you can do is to override it with the use of an amplifier stage. The power that you will need for overcoming the losses may depend on the amount of losses you are getting.


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