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Tunable RF filter based RF communications system

  • US 9,866,197 B2
  • Filed: 06/06/2014
  • Issued: 01/09/2018
  • Est. Priority Date: 06/06/2013
  • Status: Active Grant
First Claim
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1. An apparatus having a first common connection node and comprising:

  • radio frequency (RF) receive circuitry;

    RF transmit circuitry;

    a first tunable RF filter path comprising a pair of weakly coupled resonators and directly connected between the first common connection node and the RF receive circuitry, wherein an energy transfer factor between each of the pair of weakly coupled resonators is less than ten percent, the first tunable RF filter path is configured to receive and filter a first RF receive signal via the first common connection node to provide a first filtered RF receive signal to the RF receive circuitry, a first filter parameter of the first tunable RF filter path is configured to be tuned based on a first filter control signal, and the first tunable RF filter path is further configured to function as an RF lowpass filter, such that the first filter parameter of the first tunable RF filter path is a break frequency of the RF lowpass filter; and

    a second tunable RF filter path directly connected between the first common connection node and the RF transmit circuitry, wherein the second tunable RF filter path is configured to receive and filter a first RF transmit signal from the RF transmit circuitry to provide a first filtered RF transmit signal via the first common connection node, such that the apparatus is configured to be used as a TDD (Time Division Duplex) communications system, the first RF receive signal and the first filtered RF transmit signal are half-duplex signals, a first filter parameter of the second tunable RF filter path is configured to be tuned based on a second filter control signal, and the second tunable RF filter path is further configured to function as an RF highpass filter, such that the first filter parameter of the second tunable RF filter path is a break frequency of the RF highpass filter.

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