Phase shift module

A phase shifter is a microwave network which provides a controllable phase shift of the RF signal [Microwave Solid State Circuit Design, 2nd Ed., by Inder Bahl and Prakash Bhartia, John Wiley & Sons, 2003 (Chapter 12)‏] [RF MEMS Theory, Design and Technology by Gabriel Rebeiz, John Wiley & Sons, 2003 (Chapter 9-10)‏‏] [Antenna Engineering Handbook, 4th Ed., by John Volakis, McGraw-Hill, 2007 (Chapter 21)‏‏] . Phase shifters are used in phased arrays [Phased Array Antennas, 2nd Ed., by R. C. Hansen, John Wiley & Sons, 1998] [Phased Array Antenna Handbook, 2nd Ed., by Robert Mailloux, Artech House, 2005] [Phased Array Antennas by Arun K. Bhattacharyya, John Wiley & Sons, 2006] .

Classification

* Active versus passive: Active phase shifters provide gain, while passive phase shifters are lossy.
** Active:
*** Applications: active electronically scanned array (AESA)‏
*** Gain: The phase shifter amplifies while phase shifting
*** Noise figure (NF)
*** Reciprocity: not reciprocal
** Passive:
*** Applications: passive electronically scanned array (PESA)‏
*** 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 (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):
*** Passive
** Semi-conducting (RF CMOS, GaAs. SiGe, InP, GaN or Sb):
*** 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 (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