Bypass arrangement for low-noise amplifier
View Patent ↗An arrangement for bypassing a low-noise amplifier (LNA), intended especially to be used in base stations of mobile networks. For the bypass, a receiver antenna filter ( 210 ) has a second output (OUT 2 ) parallel with a first output (OUT 1 ) connected to the LNA. The antenna filter is of the resonator type, and there is a conductive element for each of its outputs in the resonator cavity. Selection between the LNA out-put signal and signal coming direct from the antenna filter is made by a changeover switch (SW). The noise figure of the receiver front stage ( 220 ) will improve as the series switch on the signal path, which most degrades the noise figure, is removed between the filter and LNA, and isolation on the LNA bypass path increases.
1. An arrangement for bypassing a low-noise amplifier in a radio receiver which comprises an antenna filter between said amplifier and an antenna, and a bypass path for said amplifier, the arrangement comprising;
at an output side of said amplifier, a changeover switch for selecting a signal to be led along a signal path either from said amplifier or from the bypass path;
said antenna filter is a resonator-type filter with an output resonator cavity having at least two parallel outputs, a first output coupled direct to an input of said amplifier and a second output coupled direct to said bypass path.
2. The arrangement according to claim 1 , wherein each of said parallel outputs has a conductive element in the output resonator cavity that conducts signal energy out of the filter.
3. The arrangement according to claim 2 , said conductive elements having substantially equally strong electromagnetic coupling to the output resonator.
4. An arrangement for bypassing a low-noise amplifier in a radio receiver which comprises an antenna filter between said amplifier and an antenna, and a bypass path for said amplifier, the arrangement comprising;
at an output side of said amplifier, a changeover switch for selecting a signal to be led along a signal path either from said amplifier or from the bypass path, said antenna filter having at least two parallel outputs, a first of which is coupled direct to an input of said amplifier, and a second of which is coupled direct to said bypass path; and
the bypass path being a galvanic conductor connection.
5. The arrangement according to claim 1 , comprising a second low-noise amplifier on the bypass path.
6. The arrangement according to claim 1 , the changeover switch being implemented by PIN diodes.
7. The arrangement according to claim 1 , the changeover switch being implemented by MEMS switches.
8. The arrangement according to claim 1 , the changeover switch being implemented by MMIC technology.
9. The arrangement according to claim 1 , the changeover switch being implemented by a relay.
10. The arrangement according to claim 1 , the bypass path being a galvanic conductor connection.
11. The arrangement according to claim 1 , wherein the resonator-type filter is one of a quarter-wave resonator, a half-wave resonator, and a plain cavity resonator.
12. The arrangement according to claim 2 , wherein said conductive elements are coupled to the respective outputs capacitively, inductively, or both capacitively and inductively.