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Wikipedia / Phase shift module

A phase shift module is a microwave network module which provides a controllable phase shift of the RF signal. Phase shifters are used in phased arrays.

Classification

Active versus passive

Active phase shifters provide gain, while passive phase shifters are lossy.

Active:

Passive:

Analog versus digital

  • Analog phase shifters provide a continuously variable phase shift or time delay.

  • 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):

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 3dB 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

  • Number of effective bits, if digital [bit]

  • Biasing: current-driven, high-voltage electrostatic [mA, V]

  • DC power consumption [mW]

  • Distortion: group velocity dispersion (GVD) [ps2/nm]

  • Gain [dB] if active, loss [dB] if passive

  • Linearity: IP3, P1dB [dBm]

  • Phase shift / noise figure [°/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