Phase shift module

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A microwave (6 to 18 GHz) Phase Shifter and Frequency Translator

A phase shift module is a microwave network module which provides a controllable phase shift of the RF signal.[1][2][3] Phase shifters are used in phased arrays.[4][5][6]


  • Active versus passive: Active phase shifters provide gain, while passive phase shifters are lossy.
  • Analog versus digital:
    • Analog phase shifters provide a continuously variable phase shift or time delay.[7]
    • Digital phase shifters provide a discrete set of phase shifts or time delays. Discretization leads to quantization errors. Digital phase shifters require parallel bus control.
  • Differential, single-ended or waveguide:
    • Differential transmission line: A differential transmission line is a balanced two-conductor transmission line in which the phase difference between currents is 180 degrees. The differential mode is less susceptible to common mode noise and cross talk.
      • Antenna selection: dipole, tapered slot antenna (TSA)
      • Examples: coplanar strip, slotline
    • Single-ended transmission line: A single-ended transmission line is a two-conductor transmission line in which one conductor is referenced to a common ground, the second conductor. The single-ended mode is more susceptible to common-mode noise and cross talk.
      • Antenna selection: double folded slot (DFS), microstrip, monopole
      • Examples: CPW, microstrip, stripline
    • Waveguide
      • Antenna selection: waveguide, horn
  • Frequency band
  • One-conductor or dielectric transmission line versus two-conductor transmission line
  • Phase shifters versus TTD phase shifter
    • A phase shifter provides an invariable phase shift with frequency, and is used for fixed-beam frequency-invariant pattern synthesis.
    • A TTD phase shifter provides an invariable time delay with frequency, and is used for squint-free and ultra wideband (UWB) beam steering.
  • Reciprocal versus non-reciprocal
    • Reciprocal: T/R
    • Non-reciprocal: T or R
  • Technology
    • Non semi-conducting (ferrite, ferro-electric, RF MEMS, liquid crystal):
      • Passive
    • Semi-conducting (RF CMOS, GaAs. SiGe, InP, GaN or Sb):
  • Design
    • Loaded-line:
      • Distortion:
        • Distorted if lumped
        • Undistorted and TTD if distributed
    • Reflect-type:
      • Applications: reflect arrays (S11 phase shifters)
      • Distortion:
        • Distorted if S21 phase shifter, because of 3 dB coupler
        • Undistorted and TTD if S11 phase shifter
    • Switched-network
      • Network:
        • High-pass or low-pass
        • or T
      • Distortion:
        • Undistorted if the left-handed high-pass sections cancel out the distortion of the right-handed low-pass sections
    • Switched-line
      • Applications: UWB beam steering
      • Distortion: undistorted and TTD
    • Vector summing

Figures of Merit[edit]

  • Number of Effective bits, if digital [Bit]
  • Biasing: current-driven, high-voltage electrostatic [mA,V]
  • DC power consumption [mW]
  • Distortion: group velocity dispersion (GVD) [ps/(km.nm)]
  • Gain [dB] if active, loss if [dB] if passive
  • Linearity: IP3, P1dB [dBm]
  • Phase shift / noise figure [deg/dB] (phase shifter) or time delay / noise figure [ps/dB] (TTD phase shifter)
  • Power handling [mW, dBm]
  • Reliability [Cycles, MTBF]
  • Size [mm2]
  • Switching time [ns]


  1. ^ Microwave Solid State Circuit Design, 2nd Ed., by Inder Bahl and Prakash Bhartia, John Wiley & Sons, 2003 (Chapter 12)
  2. ^ RF MEMS Theory, Design and Technology by Gabriel Rebeiz, John Wiley & Sons, 2003 (Chapter 9-10)
  3. ^ Antenna Engineering Handbook, 4th Ed., by John Volakis, McGraw-Hill, 2007 (Chapter 21)
  4. ^ Phased Array Antennas, 2nd Ed., by R. C. Hansen, John Wiley & Sons, 1998
  5. ^ Phased Array Antenna Handbook, 2nd Ed., by Robert Mailloux, Artech House, 2005
  6. ^ Phased Array Antennas by Arun K. Bhattacharyya, John Wiley & Sons, 2006
  7. ^ Microwave Phase Shifter information from Herley General Microwave

External links[edit]