Phase Shift

phase-frequency filter -pll

φ

Phase shifter

Phase shift module

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]

A microwave (6 to 18 GHz) Phase Shifter and Frequency Translator. Picture courtesy of Herley

Contents

1 Classification 2 Figures of Merit 3 References 4 External links

Classification[edit]

Active versus passive: Active phase shifters provide gain, while passive phase shifters are

lossy. Active:

Applications: active electronically scanned array (AESA), passive electronically scanned array (PESA)

Gain: The phase shifter amplifies while phase shifting Noise figure  (NF) Reciprocity: not reciprocal

Passive: Applications: active electronically scanned array (AESA), 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.[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):

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  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]

References[edit]

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, 19985. ̂  Phased Array Antenna Handbook, 2nd Ed., by Robert Mailloux, Artech House, 20056. ̂  Phased Array Antennas by Arun K. Bhattacharyya, John Wiley & Sons, 20067. ̂  Microwave Phase Shifter information from Herley General Microwave

External links[edit]

Website on Phase Shifters in Microwaves

Microwave Phase Shifter  information from Herley General Microwave

[1]  A low cost electro-mechanical phase shifter design, including a brief summary of solid

state methods @ www.activefrance.com