US 10,903,544 B2Granted

Magnetic balun/transformer with post processing adjustments

AssigneeInternational Business Machines Corporation

InventorsSudipto Chakraborty, Rajiv Joshi, Steven J. Holmes, Bruce B. Doris

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Abstract

A high input impedance magnetic balun/transformer having a phase balancing network (PBN) and method of operating. The balun is fully configurable and trimmable post fabrication using independently adjustable resistive and reactive parts by changing the resistance of a programmed transistor, e.g., NMOS. Parallel connected legs each having a field effect transistors (FETs) that make up NMOS device alter the impedance at the balun output terminals. The ground terminal of a secondary winding or coil at an unbalanced, single-ended side is connected to a phase balancing network. The phase balancing network includes at least two parallel legs, each leg having a resistive element in the form of a transistor device and at least one leg including a capacitive element. The transistor device at a leg can be operated in a linear region to trim the resistance and capacitances at the unbalanced side in order to achieve proper phase balancing and amplitude matching.

Claims19

Dependent claims

A method of operating a magnetic balun in a radio frequency circuit, said balun having first and second input terminal receiving input signals from a signal source, and first and second output terminals, a first output terminal providing a single-ended output signal based on said received input signals, said balun comprising a primary winding or coil connecting said first and second input terminal for receiving said input signals, said method comprising:

sensing, at a detecting circuit, a phase or amplitude imbalance of received input signals at said primary winding, the detecting circuit generating one or more control signals responsive to a detected phase or amplitude imbalance, wherein said received input signals are differential signals, said sensing comprising:
using the detecting circuit to sense a common mode signal at a center tap terminal of the primary winding, said imbalance of received input signals being detected based on said sensed common mode signal;
and
receiving, at a phase balancing circuit connected to said second output terminal, said generated one or more control signals, said phase balancing circuit comprising a parallel connection of resistance components and capacitor components connecting to a ground, each resistance components and capacitor component connected with a respective switching element, a switching element receiving said control signals to switch in a parallel configuration of resistance and/or capacitor elements to modify an impedance at said output terminals to achieve independent adjustment of a phase or amplitude at said single-ended output.

1 more element

A magnetic balun comprising:

first and second input terminals receiving differential signals from a signal source;
first and second output terminals of a single-ended side, a first output terminal providing a single-ended output signal based on said received differential signals;
and
a phase balancing circuit connected to said second output terminal coupled at the single-ended side, the phase balancing circuit comprising a parallel connection of resistance components and capacitor components connecting to a ground, each resistance components component and capacitor component of a respective leg connected to a respective switching element, said phase balancing circuit configurable to switch in a parallel configuration of resistance and capacitor elements to modify an impedance at said output terminals to achieve independent adjustment of a phase or amplitude at said single-ended output;
and
a detector circuit connected to a center tap terminal between said first and second input terminals for sensing the common mode signal and detecting an imbalance at said differential signals, the detector circuit generating one or more control signals for receipt at said switching elements of said phase balancing circuit for controlling said switching elements in said phase balancing circuit to switch in a parallel configuration of resistance and/or capacitor elements responsive to said common mode signal at said center tap.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/394,608Filed 25 Apr 2019
Published: US 2020/0343614 A129 Oct 2020
Granted: 26 Jan 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H01P 5/10
For linking dissimilar lines or devices: for coupling balanced lines or devices with unbalanced lines or devices
H03H 7/42
Multiple-port networks comprising only passive electrical elements as network components: networks for transforming balanced signals into…
H03H 5/003
One-port networks comprising only passive electrical elements as network components: comprising distributed impedance elements together with…
H01P
Waveguides