Balun having asymmetric inductors and adjustable impedance transformation ratio
AssigneeQUALCOMM Incorporated
InventorsFoad Arfaei Malekzadeh, Jorge Garcia, Jeremy Darren Dunworth
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Abstract
A balun circuit includes a first transformer comprising a first inductor and a second inductor, the first inductor having an electrical value different than the second inductor, a second transformer comprising a third inductor and a fourth inductor, the third inductor having an electrical value different than the fourth inductor, the first inductor connected to a positive terminal of a balanced port, the third inductor connected to a negative terminal of the balanced port, the second inductor connected to an unbalanced port and the fourth inductor connected to a node.
Claims23
A balun circuit, comprising:
- a first transformer comprising a first inductor and a second inductor, the first inductor having an electrical value different than the second inductor;
- a second transformer comprising a third inductor and a fourth inductor, the third inductor having an electrical value different than the fourth inductor, the first inductor connected to a positive terminal of a balanced port, the third inductor connected to a negative terminal of the balanced port, the second inductor connected to an unbalanced port and the fourth inductor connected to a node;
- a first capacitance connected across the first inductor;
- a second capacitance connected across the third inductor;
- a third capacitance connected between the unbalanced port and system ground;
- a fourth capacitance connected between the node and system ground;
- a first center tap between the second inductor and the fourth inductor;
- and
- a fifth capacitance connected between the first center tap and system ground.
A method for signal conversion, comprising:
- adjusting the impedance transformation ratio (ITR) of a balun circuit by selecting capacitance values, the balun circuit comprising two asymmetric transformers, and the capacitance values being for capacitors coupled to a balanced node or an unbalanced node of the balun circuit;
- and
- converting a signal between balanced and unbalanced using the balun circuit,
- wherein a selected impedance transformation ratio (ITR) provides a non-quarter wavelength impedance transformation.
A balun circuit, comprising:
- a pair of asymmetric transformers coupled together;
- and
- a pair of capacitors respectively directly connected across inductors on a balanced side of the asymmetric transformers,
- wherein inductors on an unbalanced side of the pair of asymmetric transformers have approximately equal inductance.
Dependencies are inferred from the claim text.