Balun

About: Balun is a research topic. Over the lifetime, 5375 publications have been published within this topic receiving 52256 citations. The topic is also known as: Telephone balance unit.

Common mode signal rejection methods for MRI: Reduction of cable shield currents for high static magnetic field systems

Abstract: This experiment was conducted to identify common mode currents that flow on the shield of a coaxial cable and to investigate techniques that reduce their effects at high fields of ≥3 Tesla. It will be shown that there are two different methods of common mode interference for two different coil types. First, is the transceive case, where common mode cable shield currents flow as a result of unbalanced loop voltages that couple to the cable shield. In the second case, unwanted common mode signals are induced from the field of the transmission coil onto the cable shield of the receive-only coil. Two important factors relating to the investigation of common mode signals are danger to the patient from an RF burn and the reduction of the signal-to-noise ratio (SNR) because of extra noise being introduced into the MRI environment. It will be shown that through the use of cable shield traps and balun matching circuits, common mode signals can be reduced significantly, increasing patient safety and SNR. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 19B: 1–8, 2003.

Balanced antenna system

Abstract: The invention relates to a balanced antenna system comprising a radiator connected via a matching circuit to a balun. In certain embodiments, the radiator comprises a first radiating element and a second radiating element and the matching circuit comprises a first impedance-matching circuit connected to the first radiating element and a second impedance-matching circuit connected to the second radiating element. The first and second matching circuits may be identical and are connected through the balun to a single port. To minimise the component count, the design of the matching circuit and balun is co-optimised.

CMOS RF amplifier and mixer circuits utilizing complementary Characteristics of parallel combined NMOS and PMOS devices

Abstract: Design and chip fabrication results for complementary RF circuit topologies that utilize the complementary RF characteristics of both NMOS and PMOS field-effect-transistor devices combined in parallel way are reported, which can inherently provide single-ended differential signal-processing capability, requiring neither baluns, nor differential signal generating/combining circuits. The proposed complementary CMOS parallel push-pull (CCPP) amplifier gives an order of magnitude improvement in IP/sub 2/ than an NMOS common-source amplifier and single-balanced CCPP resistive mixer, which functions effectively as a double-balanced one, provides more than an order of magnitude better linearity in IP/sub 2/, and similar order of magnitude better local oscillator (LO)-IF and LO-RF isolations than NMOS counterparts.

Compact multilayer BALUN for RF integrated circuits

Abstract: A compact BALUN transformer comprises a primary and a secondary conductor loop. Each of these loops are disposed in a substantially flat spiral configuration. However, one of these loops, either the primary or the secondary, is preferably disposed in a multi-layer (stacked) configuration. The stacking of at least one of the primary or secondary layers in a multi-layer arrangement provides an increase of impedance in one of the loops. This increased impedance for impedance matching purposes comes with the advantage that parasitic capacitance between primary and secondary layers as would normally be introduced in a multi-layer configuration is absent. In another embodiment of the present invention, both conductor loops are disposed in a multi-layer configuration. Such configurations are particularly useful for 1 to 1 impedance matching conditions and for somewhat lower frequency BALUN circuits.

Hybrid-balun for splitting/combining RF power

Abstract: An in-phase hybrid and a balun in a single stage built with inexpensive coaxial cable which splits or combines RF power and simultaneously performs a balanced-to-unbalanced impedance transformation.