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Wireless systems employing frequency-division duplexing (FDD) must use duplexing filters to isolate the sensitive receiver from its own strong transmission. The number of filters in the duplexer is equal to the total number of aggregated transmit and receive bands. These filters are nontunable; therefore, a separate duplexer is required for each combination of operating bands. This paper presents...
Passive filters are implemented via advanced technologies in the form of surface acoustic wave (SAW) and thin film bulk acoustic resonator (FBAR) devices. These not only exhibit low noise and high linearity features, but also have fixed centre frequency and bandwidth, making them inflexible. Adaptive duplexing eliminates the need for switched multiple band reject filters (BRF) by using a cancellation...
A Software-Defined Radio (SDR) mobile handset must cover multiple frequency bands with different frequency division duplex distances. This calls for an adaptive duplexer, which needs a low-isolation device to create an initial isolation. Such a device is implemented in a 130nm Silicon-on-Insulator (SOI) process. Its performance benefits from a high-Q laminated PCB inductor which has a measured inductance...
This paper presents an adaptive duplexer using cancelling instead of filtering to obtain sufficient transmitter (Tx) leakage and noise isolation in the receiver. A low level pseudo-noise (PN) pilot signal is introduced in order to adjust the cancelling coefficients. To modulate the pilot signal to radio frequencies a straightforward direct up-conversion mixer with low carrier feedthrough has been...
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