Out-of-band rejection using saw-based integrated balun and a differential low noise amplifier
A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode. The first interdigital transducer electrode may be single-ended with a first input bus bar that receives an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The front-end module may include a low noise amplifier (LNA) that outputs a differential signal via a differential output and has a differential input connected to the acoustic wave filter. The LNA may include a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.
1. A front-end module comprising:
an acoustic wave filter including a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode being single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground, and the second interdigital transducer electrode being differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal;
a low noise amplifier with a differential input electrically connected to the acoustic wave filter, the low noise amplifier including a first input transistor configured to receive a first signal from the first output terminal of the acoustic wave filter and a second input transistor configured to receive a second signal from the second output terminal of the acoustic wave filter, the low noise amplifier configured to output a differential signal via a differential output; and
a balun electrically connected to the differential output of the low noise amplifier, the balun being a transformer balun that is configured to convert a differential output to a single-ended output.
2. The front-end module of claim 1 wherein the differential output includes a first output node and a second output node.
3. The front-end module of claim 2 wherein the first output node is connected to a drain of the first input transistor and the second output node is connected to a drain of the second input transistor.
4. The front-end module of claim 1 wherein the first output terminal is a positive terminal and the second output terminal is a negative terminal.
5. The front-end module of claim 1 wherein the acoustic wave filter is one of a surface acoustic wave filter, a bulk acoustic wave filter, a temperature compensated surface acoustic wave filter, or a film bulk acoustic wave filter.
6. The front-end module of claim 1 further comprising a first matching circuit connected between the first output terminal of the acoustic wave filter and the first input transistor of the low noise amplifier.
7. The front-end module of claim 6 further comprising a second matching circuit connected between the second output terminal of the acoustic wave filter and the second input transistor of the low noise amplifier.
8. The front-end module of claim 6 wherein the first matching circuit is configured to perform impedance matching between the acoustic wave filter and the low noise amplifier.
9. The front-end module of claim 1 further comprising a second acoustic wave filter.
10. The front-end module of claim 9 wherein the differential output of the low noise amplifier includes a first output node and a second output node, and the second acoustic wave filter includes a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode of the second acoustic wave filter being differential, and having a first input bus bar configured to receive a first input signal from the first output node and a second input bus bar configured to receive a second input signal from a second output node, and the second interdigital transducer electrode being single-ended with a first output bus bar connected to an output terminal and a second output bus bar connected to ground.
11. The front-end module of claim 9 wherein the second acoustic wave filter is of a different type or is configured differently than the acoustic wave filter.
12. The front-end module of claim 1 wherein a connection between the acoustic wave filter and the low noise amplifier is configured to provide balun functionality between the acoustic wave filter and the low noise amplifier without inclusion of a balun circuit element before the differential input of the low noise amplifier.
13. A multi-chip module comprising:
a stacked filter low noise amplifier circuit including an acoustic wave filter and a low noise amplifier with a differential input electrically connected to the acoustic wave filter, the acoustic wave filter including a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode being single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground, and the second interdigital transducer electrode being differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal, and the low noise amplifier including a first input transistor configured to receive a first signal from the first output terminal of the acoustic wave filter and a second input transistor configured to receive a second signal from the second output terminal of the acoustic wave filter, the low noise amplifier configured to output a differential signal via a differential output; and
a signal converter configured to convert the differential signal from the differential output to a single signal, the signal converter including a balun electrically connected to the differential output of the low noise amplifier, and the balun being a transformer balun that is configured to convert a differential output to a single-ended output.
14. The multi-chip module of claim 13 wherein the signal converter includes a second acoustic wave filter that includes a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode of the second acoustic wave filter being differential, and having a first input bus bar configured to receive a first input signal from a first output node of the low noise amplifier and a second input bus bar configured to receive a second input signal from a second output node of the low noise amplifier, and the second interdigital transducer electrode being single-ended with a first output bus bar connected to an output terminal and a second output bus bar connected to ground.
15. The multi-chip module of claim 13 further comprising a first matching circuit connected between the first output terminal of the acoustic wave filter and the first input transistor of the low noise amplifier, and a second matching circuit connected between the second output terminal of the acoustic wave filter and the second input transistor of the low noise amplifier.
16. The multi-chip module of claim 13 wherein the differential output includes a first output node and a second output node, and the first output node is connected to a drain of the first input transistor and the second output node is connected to a drain of the second input transistor.
17. The multi-chip module of claim 13 wherein a connection between the acoustic wave filter and the low noise amplifier is configured to provide balun functionality between the acoustic wave filter and the low noise amplifier without inclusion of a balun circuit element before the differential input of the low noise amplifier.
18. A wireless device comprising:
an antenna configured to receive a plurality of signals, each signal of the plurality of signals associated with a different frequency band; and
a front-end module including an acoustic wave filter, a low noise amplifier with a differential input electrically connected to the acoustic wave filter, and a balun, the acoustic wave filter including a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode being single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground, and the second interdigital transducer electrode being differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal, and the low noise amplifier including a first input transistor configured to receive a first signal from the first output terminal of the acoustic wave filter and a second input transistor configured to receive a second signal from the second output terminal of the acoustic wave filter, the low noise amplifier configured to output a differential signal via a differential output, the balun electrically connected to the differential output of the low noise amplifier, and the balun being a transformer balun that is configured to convert a differential output to a single-ended output.
19. The wireless device of claim 18 wherein the acoustic wave filter and the low noise amplifier are implemented in a stacked filter low noise amplifier circuit.
20. The wireless device of claim 18 wherein the front-end module includes a second acoustic wave filter that includes a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode of the second acoustic wave filter being differential, and having a first input bus bar configured to receive a first input signal from a first output node of the low noise amplifier and a second input bus bar configured to receive a second input signal from a second output node of the low noise amplifier, and the second interdigital transducer electrode being single-ended with a first output bus bar connected to an output terminal and a second output bus bar connected to ground.