FRONT END MODULE WITH SCALABLE IMPEDANCE BALANCING
A radio front end includes a power amplifier, a duplexer, a detection module, a processing module, and a tunable balancing network. The duplexer is operable to provide electrical isolation between the outbound wireless signal and an inbound wireless signal. The detection module is operable to detect non-linear function of the power amplifier to produce a detected non-linearity and to detect transmit leakage of the duplexer to produce detected transmit leakage. The processing module is operable to generate a coarse tuning signal based on the detected non-linearity and to generate a fine tuning signal based on the detected transmit leakage. The tunable balancing network is operably coupled to the duplexer and operable to establish an impedance based on the coarse and fine tuning signals.
1 . A radio front end comprises:
a power amplifier operable to amplify an up-converted signal to produce an outbound wireless signal;
a duplexer operably coupled to an antenna, wherein the duplexer is operable to provide dynamic electrical isolation between the outbound wireless signal and an inbound wireless signal;
a detection module operable to:
detect non-linear function of the power amplifier to produce a detected non-linearity; and
detect transmit leakage of the duplexer to produce detected transmit leakage;
a processing module operable to:
generate a coarse tuning signal based on the detected non-linearity; and
generate a fine tuning signal based on the detected transmit leakage; and
a tunable balancing network operably coupled to the duplexer and operable to establish an impedance based on the coarse and fine tuning signals.
2 . The radio front end of claim 1 , wherein the detection module further functions to:
determine non-linearity of on-resistance of one or more transistors within the power amplifier;
develop an envelope signal that tracks variations of the power amplifier based on the non-linearity of the on-resistance, wherein the processing module generates the coarse tuning signal based on the envelope signal.
3 . The radio front end of claim 1 , wherein the detection module further functions to:
determine a common mode offset of the duplexer; and
determine the transmit leakage from the common mode offset.
4 . The radio front end of claim 1 further comprises:
the processing module operable to:
determine a transmit power level of the outbound wireless signal;
when the transmit power level compares favorably with an isolation requirement, generate an isolation adjustment signal; and
send the isolation adjustment signal to at least one of the duplexer and the tunable balancing network; and
the at least one of the duplexer and the tunable balancing network adjusts the dynamic electrical isolation between the outbound wireless signal and the inbound wireless signal based on the isolation adjustment signal.
5 . The radio front end of claim 4 , wherein the duplexer comprises:
a frequency selective duplexer that includes one or more filters, wherein the frequency selective duplexer adjusts the dynamic electrical isolation between the outbound wireless signal and the inbound wireless signal by adjusting a filter of the one or more filters.
6 . The radio front end of claim 4 further comprises:
the duplexer including an electrical-balance duplexer; and
the processing module operable to send the isolation adjustment signal to the tunable balancing network, wherein the tunable balancing network adjusts the impedance based on the isolation adjustment signal as a trade-off between loading of the duplexer and the dynamic electrical isolation between the inbound and outbound wireless signals.
7 . The radio front end of claim 1 further comprises:
a front end module that includes the duplexer, the power amplifier, and the tunable balancing network; and
a radio transceiver module that includes the processing module and at least a portion of the detection module.
8 . A radio front end comprises:
a power amplifier operable to amplify an up-converted signal to produce an outbound wireless signal;
a duplexer operably coupled to an antenna, wherein the duplexer is operable to provide dynamic electrical isolation between the outbound wireless signal and an inbound wireless signal;
a tunable balancing network operably coupled to the duplexer and operable to establish an impedance; and
a processing module operable to:
determine a transmit power level of the outbound wireless signal;
when the transmit power level compares favorably with an isolation requirement, generate an isolation adjustment signal; and
send the isolation adjustment signal to at least one of the duplexer and the tunable balancing network; wherein the at least one of the duplexer and the tunable balancing network adjusts the dynamic electrical isolation between the outbound wireless signal and the inbound wireless signal based on the isolation adjustment signal.
9 . The radio front end of claim 8 , wherein the duplexer comprises:
a frequency selective duplexer that includes one or more filters, wherein the frequency selective duplexer adjusts the dynamic electrical isolation between the outbound wireless signal and the inbound wireless signal by adjusting a filter of the one or more filters.
10 . The radio front end of claim 8 further comprises:
the duplexer including an electrical-balance duplexer; and
the processing module operable to send the isolation adjustment signal to the tunable balancing network, wherein the tunable balancing network adjusts the impedance based on the isolation adjustment signal as a trade-off between loading of the duplexer and the dynamic electrical isolation between the inbound and outbound wireless signals.
11 . The radio front end of claim 8 further comprises:
a detection module operable to:
detect non-linear function of the power amplifier to produce a detected non-linearity; and
detect transmit leakage of the duplexer to produce detected transmit leakage;
the processing module operable to:
generate a coarse tuning signal based on the detected non-linearity; and
generate a fine tuning signal based on the detected transmit leakage; and
the tunable balancing network operable to further establish the impedance based on at least one of the coarse and fine tuning signals.
12 . The radio front end of claim 8 further comprises:
a front end module that includes the duplexer, the power amplifier, and the tunable balancing network; and
a radio transceiver module that includes the processing module.
13 . A front end module comprises:
a power amplifier operable to amplify an up-converted signal to produce an outbound wireless signal;
a duplexer operably coupled to an antenna, wherein the duplexer is operable to provide dynamic electrical isolation between the outbound wireless signal and an inbound wireless signal; and
a tunable balancing network operably coupled to the duplexer and operable to establish an impedance based on at least one of an isolation adjustment signal, a coarse tuning signal, and a fine tuning signal, wherein the coarse tuning signal compensates for a non-linearity of the power amplifier, the fine tuning signal compensates for transmit leakage of the duplexer, and the isolation adjustment signal adjusts the dynamic electrical isolation based on transmit power level of the outbound wireless signal.
14 . The front end module of claim 13 , wherein the duplexer comprises:
a frequency selective duplexer that includes one or more filters, wherein the frequency selective duplexer adjusts the dynamic electrical isolation between the outbound wireless signal and the inbound wireless signal by adjusting a filter of the one or more filters.
15 . The front end module of claim 13 further comprises:
the duplexer including an electrical-balance duplexer, wherein the tunable balancing network adjusts the impedance based on the isolation adjustment signal as a trade-off between loading of the duplexer and the dynamic electrical isolation between the inbound and outbound wireless signals.
16 . The front end module of claim 13 , wherein the balancing network comprises at least one of:
a tunable resistor-capacitor network;
a tunable inductor-capacitor network; and
a tunable resistor-inductor-capacitor network.