Phase shifter

This article is about the microwave device. For the guitar effect, see Phaser (effect).
"Phase shifter" redirects here. For the type of transformer, see quadrature booster.


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

Classification

  • 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
    • One-conductor or dielectric transmission line (optical fibre, finline, waveguide):
      • Modal
      • No TEM or quasi-TEM mode, not TTD or quasi-TTD
      • Higher-order TE, TM, HE or HM modes are distorted
    • Two-conductor transmission line (CPW, microstrip, slotline, stripline):
      • Differential or single-ended
      • TEM or quasi-TEM mode is TTD or quasi-TTD
  • 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
        • \pi 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

  • # 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]‏

References

External links

  • Website on Phase Shifters in Microwaves
  • Herley General Microwave
  • [1] A low cost electro-mechanical phase shifter design, including a brief summary of solid state methods @ www.activefrance.com
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