Hello,
I would like to know what type/part number of inductor used for L1 (330 nH) on TGA2237-SMEVB Evalution Board schematic. (TGA2237-SM Datasheet, page 14).
https://www.qorvo.com/products/d/da003961
I`m designing 700-2400 MHz 10W PA and would like to check my design vs Qorvo design.
At least I need recommendation for Bias Tee selection (inductor SRF, for example)
– Kind Regards,
Victor
Hello Victor. I will relate a prior summary of the inductor recommendation from some years ago. It is possible that the Exact Coilcraft part numbers are no longer available, but they may have an equivalent or improved version:
The official 330 nH, 1206 wirewound inductor would be something like:
Coilcraft: 1206CS-331XJLC
Max. current for the Coilcraft is 590 mA (as well as a similar AVX, LCWC series). The part is spec’d to 125°C, so the current rating also factors in that max. temp.
The TGA2237-SM will be operating at 630 mA Id drive nominal with RF input. Product apps thinks that this will still be OK, especially if it is a pulsed use.
If the customer will be operating at 100 MHz or greater, a smaller inductor value of 180 nH would be recommended and would have a higher max. current rating of 700 mA, providing more margin on the current rating. If Coilcraft, it would be:
1206CS-181XJLC
Hello DSO,
Thank you for answer.
1206CS-331XJLC have 650 MHz SRF.
and 1206CS-181 have 900 Mhz SRF.
Both inductor’s SRF much lower then Reference Design maximum operation frequency (2.5GHz)
I`m little bit confused…
Hi Victor. It is fairly common to need to use choke values with gain blocks, other wide band amps, etc., where the SRF is lower than max. operating frequency due to the minimum device operating frequency. In practice, I have not seen this to be much of a concern as many of our gain blocks recommend inductors (acting as chokes) with SRF in-band. For instance, the older SBB4089Z has this same situation (SRF min. = 1000 MHz) for the recommended 82 nH Coilcraft inductor used a choke. The SBB4089Z min/max is 50-6000 MHz. You could experiment with a smaller inductor value with higher SRF as your min. operating frequency is 700 MHz (such as 68 nH) but SRF may still be in-band.