Digitally tuned, integrated baluns with enhanced linearity for multi-band radio applications
First Claim
1. A multi-band balun comprising:
- a low pass filter having a number of tuning networks to achieve tunable reactive elements within the low pass filter, each tuning network in said low pass filter including at least one switching transistor and at least one fixed reactive element, wherein an input of said low pass filter forms a first differential port of said balun; and
a high pass filter having a number of tuning networks to achieve tunable reactive elements within the high pass filter, each tuning network in said high pass filter including at least one switching transistor and at least one fixed reactive element, wherein an input of said high pass filter forms a second differential port of said balun and an output of said high pass filter is coupled to an output of said low pass filter to form a single-ended port of said balun;
wherein said low pass filter and said high pass filter are integrated on a semiconductor chip.
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Abstract
An integrated balun includes a low pass filter and a high pass filter that are formed on a semiconductor chip using tunable reactive elements. The outputs of the low pass filter and the high pass filter are tied together to form the single ended output of the balun. The inputs of the low pass filter and the high pass filter form the differential inputs of the balun. The low pass filter and the high pass filter each include a number of tunable networks for achieving the tunable reactive elements. Each tunable network includes at least one switching transistor and at least one fixed value reactive elements. In at least one embodiment, dynamic biasing circuitry may be provided to improve the linearity and reduce the insertion loss of the balun.
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Citations
19 Claims
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1. A multi-band balun comprising:
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a low pass filter having a number of tuning networks to achieve tunable reactive elements within the low pass filter, each tuning network in said low pass filter including at least one switching transistor and at least one fixed reactive element, wherein an input of said low pass filter forms a first differential port of said balun; and a high pass filter having a number of tuning networks to achieve tunable reactive elements within the high pass filter, each tuning network in said high pass filter including at least one switching transistor and at least one fixed reactive element, wherein an input of said high pass filter forms a second differential port of said balun and an output of said high pass filter is coupled to an output of said low pass filter to form a single-ended port of said balun; wherein said low pass filter and said high pass filter are integrated on a semiconductor chip. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system comprising:
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a tunable multi-band balun that can switch between at least first and second operational frequency bands in response to a control signal; and a broadband transmit/receive (TX/RX) switch coupled to a first differential port of said tunable multi-band balun. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification