SC1894_input signal bandwith

Hello,

Please help to share below details.

1. RF Input frequency range to SC1894
2. Input channel width- 12.5 and 25KHz
3. Input power level(dBm) to SC1894
4. Modulation scheme (QPSK/QAM/ other) of signal
5. Peak to average ration of signal
6. Power amplifier output power, P1 dBm, P3dBm
7. Type of power amplifier and process
8. PA output ACLR (dBc) without correction
9. Expected ACLR correction 30 dBc
10. Any up converter or down converter planned to use?
11.  If yes pls share frequency details.

Thank You

RF products support team.

Dear team,

refer to the following comments.

1. RF Input frequency range to SC1894
   ==>156.0125~162.0375MHz
2. Input channel width- 12.5KHz and 25KHz
  ==>Input channel bandwidth is 12.5KHz, 25KHz
3. Input power level(dBm) to SC1894
  ==> About 0dBm(adjustable)
4. Modulation scheme (QPSK/QAM/ other) of signal
  ==>QPSK&8PSK&16QAM&64QAM&CDMA etc
5. Peak to average ration of signal
  ==>3~6dB
6. Power amplifier output power, P1 dBm, P3dBm
  ==> Average outpower : 12Watt (LDMOS Tr : 60Watt)

7. Type of power amplifier and process
  ==> LDMOS
8. PA output ACLR (dBc) without correction
  ==> about 30 dBc
9. Expected ACLR correction 30 dBc
 ==>Need to 30 dB improvement
10. Any up converter or down converter planned to use?
 ==> No
11. If yes pls share frequency details.

Thank you.

Regards,

Josh

Hello,

There are a couple of versions of the SC1894.  The 00C13 version and the 00N13 version.  The C13 version is for typical 4G/5G wireless cellular infrastructure applications though it can be also used with other signals.  The N13 version is for narrowband signals such as are used in public safety or satellite communication applications.  The only difference is in the firmware.  The C13 version will not work with such narrowband signals, so the N13 version is the only option.  Read the FW4.5.01.00 Release Notes doc downloadable from the SC1894 product web page to learn more about the narrowband part.

Based on the given specs, I think there is a possibility the N13 part may be usable.  With narrowband signals, it is the Intermodulation Distortion (IMD) products that are of primary concern.  If one has two more more narrowband carriers, there will be many IMD products generated due to the non-linearity of the power amplifier (PA).  The SC1894 will attenuate these IMDs, but the amount of attenuation is highly dependent on the PA.  30dB or so IMD correction has been observed but it will depend on your particular PA.  Another factor is that if the PA is driven so hard that it is clipping the peaks of the signal, there is critical information on the PA non-linearity, which the SC1894 requires for linearization, that is lost.  This is sometimes the case in satellite communications.  If there is just a single carrier, the distortion immediately adjacent to the carrier will have little or no attenuation, especially with a 12.5KHz carrier.  If the ACLR requirement is referring to this adjacent distortion, then I think there is no way to support this.

Regards

Andrew

Hi Addrew,

Thank you for your support.

Regards,

Josh

Hi AndrewBG,
on your opinion, what should be the best ADI solution (if exists) to linearize a PA that works with HF (1MHz to 30MHz) range with minimum signal BW of 3KHz (for non AM signal). The possible signal's modulation can be AM or FM, or digital like QAM.
I think that there's no solution for DPD, maybe a static analog predistortion, using MAX2009 or MAX2010 (with down/up conversion) , can works....
Regards
Giuseppe