2. LTE-Advanced New UE Categories[4] LTE-Advanced New UE Categories[4]

3. LTE-Advanced New UE Categories LTE-Advanced New UE Categories Advanced MIMO (Multiple Input, Multiple Output)[8].

4. LTE-Advanced New UE Categories LTE-Advanced New UE Categories Using higher-order modulation (256-QAM)[8].

5. LTE-Advanced New UE Categories LTE-Advanced New UE Categories CA + MIMO + 256 QAM[9].

6. Carrier Aggregation is the first step of LTE Advanced Bandwidth extension by aggregating LTE component carriers (CC), Up to 5 CC can be allocated in both DL and UL – 100 MHz aggregated[4]. For FDD, the CC number in DL should be larger than or equal to which in UL ; for TDD, the CC number in DL should be equal to which in UL[3].

7. Carrier Aggregation is the first step of LTE Advanced For CA, modes and deployments are as below[4]:

8. Intra-Band Uplink Challenges Intra ‐ band uplink CA signals use more bandwidth and have higher peak ‐ to ‐ average power ratios (PAPRs) than standard LTE signals because more subcarriers lead to higher PAPRs[3]. Large PAPR requires high linearity requirements for PA and increases power consumption[5].

9. Intra-Band Uplink Challenges Thus, for intra-band UL, the temperature drift of duplexer or filter should be as small as possible. This is especially important for high channel[6,9].

10. Intra-Band Uplink Challenges BAW filters are consistent performance over a wide temperature range. Qorvo LowDrift™ BAW filters achieve high isolation and low insertion loss to maximize system performance compared to competing devices using TC(Temperature Compensated) SAW/SAW[6]. >0.5 dB of nominal insertion loss improvement

11. Inter-band Challenges Take B17/B4 combination for example, the B17 3H may fall in B4 received band, thereby causing desense issue[4].

12. Inter-band Challenges The B4 desense is as shown below[4]: 6.8dB due to noise floor increase caused by harmonic 0.5 dB due to H3 trap filter insertion loss For H3 trap filter, LPF has smaller IL than BPF[10]

13. Consideration for harmonics TVS(Transient Voltage Suppression) is often added in ASM ANT port to avoid making ESD damage ASM. TVS limited VBR clips RF signal, causing distortion and then harmonics aggravates[12].

14. Consideration for harmonics For B17, if 2H noise(about 1400 MHz) exists in PA Vcc path, the 3H product may aggravate due to IMD mechanism.

15. Consideration for harmonics Apparently, PA dominates the whole 3H level[10].

16. Consideration for harmonics Therefore, the PA output impedance should be tuned to high linearity zone to achieve lower harmonics.

17. Consideration for harmonics Not only RF signal at PA input, but also 3H product generated from transceiver. If we take PA as: and take 3H product@PA input as : we can get PA output 3H product as :

18. Consideration for harmonics Obviously, as mentioned earlier, the higher 3H product at PA input leads to higher 3H product at PA output. Thus, we can add LPF or notch filter at PA input to suppress 3H product generated from transceiver, thereby lowering 3H product at PA output.

19. Inter-band Challenges For IMD3(3rd order intermodulation) calculation[10] : In addition to active devices, passive devices, such as duplexers, also generate IMD products due to nonlinearity[10,11]. For B1/B3 combination CA, 2B1TX – B3TX = B1RX. That is, B1 and B3 transmitting signals generate IMD products falling into B1 received bands, thereby causing desense issue.

20. Inter-band Challenges As shown below, the IMD3 product generated by quadplexer nonlinearity may interfere B1 RX by quadplexer, ASDiV limited isolation, and limited ANT-to- ANT isolation.

21. Inter-band Challenges Besides, 2B3TX – B1TX = GPS, the IMD3 product may interfere GPS signal as well by means of limited ANT-to- ANT isolation.

22. DL CA introduces New Requirements With DL CA, all potential transmit frequencies must be prevented from injecting excessive noise into all operating receive channels. So do all operating receive channels[1]. These two new requirements are often referred to as a need for “cross isolation”, which should be at least 50 dB[1-2].

23. DL CA introduces New Requirements Additionally, to prevent unwanted loading, all filters must have their impedances adjusted so that, for any given filter, the parallel combination of all the other filters looks like an open circuit. These requirements drive changes in FDD hardware[1]. Thus, connecting multiple duplexer paths can affect the filter characteristic of all duplexers, thereby causing you to lose transmit and receive path isolation required to operate at system sensitivity[3].

24. DL CA introduces New Requirements Besides, for TDD DL CA, if band operation is NOT synchronized, adequate cross isolation must be ensured[1].

25. DL CA introduces New Requirements In the case of aggregation of a TDD band with an FDD band, the FDD band is commonly used as p- cell (transmitting band) and the filtering in the TDD band needs to be enhanced as in the case of un- synchronized TDD-TDD DL CA. If the TDD band is used as p-cell, the Rx of the FDD duplexer needs to be enhanced to create high rejection at the TDD Band[1]. For DL intra-band CA, there is no impact on UE filtering, for either contiguous or non-contiguous CA because intra-band CA passes all the channels to be aggregated through the same power amplifier and filtering[1].

26. Inter-Band Architecture Options Each band can be on a separate antenna and antenna- to-antenna isolation is used to ensure sufficient cross isolation. The major drawback to this method is the lack of space for the required number of antennas[1].

27. Inter-Band Architecture Options A second option is to use a switch to simultaneous close connections to multiple paths, in that proper impedance loading must be maintained both with the switch closed and the switch opened. So this method needs phase shifters to prevent unwanted loading[1,7].

28. Inter-Band Architecture Options The third option is using a combination of high pass and low pass filtering, a diplexer can be used to combine any band in one frequency range with any band in a second frequency range. This technique works best when there is substantial frequency spacing between the two separate frequency ranges, e.g. separating “low” bands from “mid or high” bands[1].

29. Inter-Band Architecture Options Alternately, band pass filters can be combined into a “multiplexer” that provides a common antenna port but individually filters each Tx and Rx band. This is the preferred technique when the bands to be aggregated are close to each other in frequency[1].

30. Inter-Band Architecture Options For a multiplexer, both in-band isolations and cross isolation need to be supported and at least 50 dB. And filter impedances need to be adjusted to prevent loading. These requirements results in higher insertion loss than individual duplexers due to more poles and zeros[1]. As shown right, the ANT port matching should be wideband enough to cover band A and B, thereby increasing insertion loss due to lower Q factor[1].

31. Inter-Band Architecture Options High out of band reflection enables filters to be connected in parallel with minimal impedance loading, so better in band and cross band isolation[1]. Thus, FBAR multiplexers have lower insertion loss, higher spurious rejection, and higher in band and cross band isolation than SAW multiplexers[1].

32. Inter-Band Architecture Options Nevertheless, using the multiplexer reduces the throw count of the band select switch, which can be a significant benefit due to lower switch insertion loss and complexity. This is especially beneficial to non-CA band[1].

33. Reference [1] Multiplexers as a Method of Supporting Same-Frequency-Range Down Link Carrier Aggregation, AVAGO [2] LTE Carrier Aggregation Technology Development and Deployment Worldwide [3] ABCs of Carrier Aggregation [4] Carrier Aggregation: Fundamentals and Deployments, Keysight [5] EVM Degradation in LTE Systems by RF Filtering [6] Addressing Carrier Aggregation Challenges Using Multiplexer Solutions, Qorvo [7] FRONT-END MODULE FOR CARRIER AGGREGATION MODE, US Patent [8] Delivering on the LTE Advanced promise, Qualcomm [9] Carrier Aggregation What’s New in Mobile CA? Qorvo [10] RF Advanced (Level 3) – RF System-Training Note, Murata [11] Development of High Linearity Duplexers with Low Passive Intermodulation Component, TAIYO [12] ESD Protection Device Solutions in the vicinity of RF antenna -No Harmonic Noise, Murata