Multi-band circuit with first and second signal branches

1. A multiband circuit comprising:

a signal path comprising a first signal branch and a second signal branch, the first and second signal branches being combined on an antenna side into a common path;

wherein the first signal branch comprises a first circuit that is transmissive in a first frequency band, the first circuit having a transfer function; and

the second signal branch comprises a second circuit that is transmissive in a second frequency band and having a blocking frequency (f notch ) the second circuit being configured to shunt radio frequency (RF) signals to ground at the blocking frequency (f notch ) and connect an antenna side input of the first signal branch at RF to ground;

wherein the second circuit is configured to make a flank in the transfer function of the first circuit steeper.

2. The multiband circuit of claim 1 , wherein:

the first circuit comprises a first low-pass filter; and

the second circuit comprises a second low-pass filter, the second low-pass filter being conductively connected to the first low-pass filter and to the common path.

3. The multiband circuit of claim 2 , wherein at least one of the first and second low-pass filters in the first signal branch or second signal branch is on the antenna side.

4. The multiband circuit of claim 2 , further comprising:

a third filter downstream of the low-pass filter in the first signal branch; and a fourth filter downstream of the low-pass in the second signal branch.

5. The multiband circuit of claim 1 , wherein the second frequency band is at least one octave above the first frequency band.

6. The multiband circuit of claim 5 , wherein the blocking frequency (f notch ) is between the first and the second frequency bands.

7. The multiband circuit of claim 5 , wherein the blocking frequency (f notch ) is below the first frequency band.

8. The multiband circuit of claim 5 , wherein the blocking frequency (f notch ) is above the second frequency band.

9. The multiband circuit of claim 5 , wherein:

the first circuit comprises a high-pass filter; and the blocking frequency (f notch ) is in the passband the high-pass filter.

10. The multiband circuit of claim 5 , wherein:

the first circuit comprises a low-pass filter, and

the blocking frequency (f notch ) is in the passband of the low-pass filter.

11. The multiband circuit of claim 5 , wherein:

the first circuit (comprises a bandpass filter, and the blocking frequency (f notch ) is above the passband of the bandpass filter.

12. The multiband circuit of claim 5 , wherein:

the first circuit comprises a bandpass filter, and

the blocking frequency (f notch ) is i below the passband of the bandpass filter.

13. The multiband circuit of claim 1 , wherein each of the first and second signal branches is a transmit path.

14. The multiband circuit of claim 1 , wherein each of the first and second signal branches is a receive path.

15. The multiband circuit of claim 1 , wherein the first circuit and the second circuit include concentrated LC elements.

16. The multiband circuit of claim 1 , further comprising:

an additional signal path comprising an additional first signal branch and an additional second signal branch electrically connected on the antenna side into the common path.

17. A multiband circuit comprising:

a first signal branch transmissive in a first frequency band and a second signal branch transmissive in a second frequency band, the first and second signal branches being electrically connected on an antenna side into a common path; (RX, TX),

a first low-pass filter in the first signal branch;

a second low-pass filter in the second signal branch, the second low-pass filter being conductively connected directly to the first low-pass filter and to the common path; and

a second circuit configured to conduct RF signals to ground at a blocking frequency (f notch ) in the second signal branch.

18. An electronic component comprising:

a substrate; and

a multiband circuit in the substrate, the multiband circuit comprising:

a signal path comprising a first signal branch comprising a first circuit that is transmissive in a first frequency band and a second signal branch comprising a second circuit that is transmissive in a second frequency band, the first and second signal branches being combined on an antenna side into a common path;

wherein the second circuit has a blocking frequency (f notch ) is configured to shunt radio frequency (RF) signals to ground at the blocking frequency (f notch ) and connects an antenna side input of first signal at RF to ground and the first circuit and the second circuits include concentrated LC elements;

wherein the second circuit is further configured to make a flank in the transfer function of the first circuit steeper.

19. The component of claim 18 , wherein the substrate has ceramic layers.

20. A multiband circuit comprising:

a signal path comprising a first signal branch and a second signal branch, the first and second signal branches being combined on an antenna side into a common path;

wherein the first signal branch comprises a first circuit that is transmissive in a first frequency band, the first circuit having a transfer function; and

the second signal branch comprises a second circuit that is transmissive in a second frequency band and having a blocking frequency (f notch ) the second circuit being configured to shunt radio frequency (RF) signals to ground at the blocking frequency (f notch ) and connects an antenna side input of the first signal branch at RF to ground;

wherein the second frequency band is at least one octave above the first frequency band.