Phase shift module

Classification

Active versus passive

• Active:
• * Applications: active electronically scanned array, passive electronically scanned array
• * Gain: The phase shifter amplifies while phase shifting
• * Noise figure
• * Reciprocity: not reciprocal
• Passive:
• * Applications: active electronically scanned array, passive electronically scanned array
• * Loss: the phase shifter attenuates while phase shifting
• * NF: NF = loss
• * Reciprocity: reciprocal

  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
• * 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, 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 :
• * 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 :
• * 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 beam steering.

  Reciprocal versus non-reciprocal

• * Reciprocal: T/R
• * Non-reciprocal: T or R

  Technology

• Non semi-conducting :
• * Passive
• Semi-conducting :
• * Active: BJT or FET transistor based MMICs, RFICs or optical ICs
• * Passive: PIN diode based hybrids

  Design

• Loaded-line:
• * Distortion:
• ** Distorted if lumped
• ** Undistorted and TTD if distributed
• Reflect-type:
• * Applications: reflect arrays
• * 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

• Number of Effective bits, if digital
• Biasing: current-driven, high-voltage electrostatic
• DC power consumption
• Distortion: group velocity dispersion
• Gain if active, loss if passive
• Linearity: IP3, P1dB
• Phase shift / noise figure or time delay / noise figure
• Power handling
• Reliability
• Size
• Switching time