Reducing insertion loss in LNA bypass mode by using a single-pole-triple-throw switch in a RF front end module
A microwave radio frequency (RF) front end module (FEM) having a low noise amplifier (LNA) with a bypass mode uses a single-pole-triple-throw RF switch that reduces insertion loss to about 1 dB and thereby improves RF receiver sensitivity over existing technology two series connected single-pole-double throw RF switches. The single-pole-triple-throw RF switch may be three metal oxide semiconductor field effect transistor (MOSFET) RF switches that may be arranged with a common source input and isolated independent drain outputs. The RF switches may be single, double or triple gate MOSFET RF switches. The MOSFET RF switches may also be configured as complementary metal oxide semiconductor (CMOS) field effect transistor (FET) RF switches.
1. A radio frequency (RF) from end module (FEM), comprising:
a low noise amplifier (LNA) having an input and an output; and
a single-pole-triple-throw (SPTT) switch having a common and selectable first, second and third positions, wherein the common is coupled to an antenna node, the first position is coupled to a transmitter input node, the second position is coupled to a receiver output node,and the third position is coupled to the input of the LAN.
2. The RF FEM according to claim 1 , further comprising a direct current (DC) blocking capacitor between the common of the SPTT switch and the antenna node.
3. The RF FEM according to claim 1 , further comprising a direct current (DC) blocking capacitor between the first position of the SPTT switch and the transmitter input node.
4. The RF FEM according to claim 1 , further comprising a direct current (DC) blocking capacitor between the second position of the SPIT switch and the receiver output node.
5. The RF FEM according to claim 1 , further comprising a RF disconnect switch between the output of the LAN and the receiver output node.
6. The RF FEM according to claim 5 , further comprising a direct current (DC) blocking capacitor between the RF disconnect switch and the receiver output node.
7. The RF FEM according to claim 1 , wherein the SPTT switch comprises first, second and third metal oxide semiconductor field effect transistors (MOSFETs), wherein:
sources of the first, second and third MOSFETs are coupled to the antenna node;
a drain of the first MOSFET is coupled to the transmitter input node;
a drain of the second MOSFET is coupled to the receiver output node;
a drain of the third MOSFET is coupled to the input of the LAN; and
gates of the first, second and third MOSFETs are coupled to a RF switch controller.
8. The RF FEM according to claim 7 , wherein each of the first, second and third MOSFETs comprises a single gate.
9. The RF FEM according to claim 8 , wherein the integrated circuit die is encapsulated in an integrated circuit package having a plurality of connection nodes thereon.
10. The RF FEM according to claim 7 , wherein each of the first, second and third MOSFETs comprises a dual gate.
11. The RF FEM according to claim 7 , wherein each of the first, second and third MOSFETs comprises a triple gate.
12. The RF FEM according to claim 1 , wherein the SPTT switch comprises first, second and third metal oxide semiconductor field effect transistors (MOSFETs), wherein:
drains of the first, second and third MOSFETs are coupled to the antenna node;
a source of the first MOSFET is coupled to the transmitter input node;
a source of the second MOSFET is coupled to the receiver output node;
a source of the third MOSFET is coupled to the input of the LAN; and
gates of the first, second and third MOSFETs are coupled to a RF switch controller.
13. The RF FEM according to claim 12 , wherein each of the first, second and third MOSFETs comprises a single gate.
14. The RF FEM according to claim 12 , wherein each of the first, second and third MOSFETs comprises a dual gate.
15. The RF FEM according to claim 12 , wherein each of the first, second and third MOSFETs comprises a triple gate.
16. The RF FEM according to claim 1 , wherein the LAN and the SPTT switch are fabricated on an integrated circuit die.
17. The RF FEM according to claim 1 , wherein the LAN and the SPTT switch operate at gigahertz frequencies.
18. A radio frequency device, comprising:
a power amplifier, an input matching circuit coupled to an input of the power amplifier and a low pass filter coupled to an output of the power amplifier; and
a radio frequency (RF) front end module (FEM), comprising:
a low noise amplifier (LNA) having an input and an output; and
a single-pole-triple-throw (SPTT) switch having a common and selectable first, second and third positions, wherein the common is coupled to an antenna node, the first position is coupled to an output of the low pass filter, the second position is coupled to a receiver output node, and the third position is coupled to the input of the LAN.
19. The radio frequency device according to claim 18 , wherein the power amplifier, LAN and SPTT switch are fabricated on an integrated circuit die.
20. The radio frequency device according to claim 19 , wherein the integrated circuit die is encapsulated in an integrated circuit package having a plurality of connection nodes thereon.
21. The radio frequency device according to claim 18 , wherein the power amplifier, LAN and SPTT switch operate at gigahertz frequencies.