Walsin RF Second Source for United States Buyers: 98 of 165 Band Shelves Hold One Part

If you design in a Walsin RF part, there is a 21% chance no second Walsin part stands behind it. We sorted all 457 RF part numbers into 165 shelves by function, type, case size and band. 98 shelves hold exactly one part. A Walsin RF second source is often a shelf of one.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 15 radio frequency parametric export files published by Walsin Technology (Walsin). We have already published the coupler and multiplexer figure — 33 shelves, 17 of them holding one part number. This post extends the same count to filters, baluns, SAW and BAW, and gives the whole-line number across all 457 parts. Every part number below is real and every figure is the export’s own, because we hold no RF datasheet of any kind.

How many Walsin RF band shelves hold more than one part in the same function?

67 of 165. We built one shelf per combination of function, published type, case size and normalised frequency band, then counted the parts on each. 98 shelves hold exactly one part number. 33 hold exactly two. 131 of 165 shelves hold two parts or fewer. The single deepest shelf in the whole line holds 40 parts: 2012 band pass filters at 2400-2500 MHz.

Function	Export file	Parts	Shelves	Shelves with 1 part	Shelves with 2+
Filter (LTCC)	Walsin_Filter.xlsx	235	84	47	37
Multiplexer	Walsin_Multiplexer.xlsx	116	27	14	13
Balun	Walsin_Balun.xlsx	72	32	19	13
Coupler	Walsin_Coupler.xlsx	17	6	3	3
Antenna switch	Walsin_Antenna_Switch.xlsx	9	8	7	1
BAW filter	Walsin_BAW_Filter.xlsx	5	5	5	0
SAW filter	Walsin_SAW_Filter.xlsx	3	3	3	0
Whole line	all 15 files	457	165	98	67

Our previously published coupler and multiplexer total reproduces exactly from this method: 6 plus 27 is 33 shelves, 3 plus 14 is 17 single-part shelves. We have not seen the whole-line figure counted anywhere. 98 of 165, measured 12 October 2026 from the files as they stand.

Which functions are thinnest once the coupler and multiplexer count is extended?

The acoustic parts, absolutely. Extending the count to filters, baluns, SAW and BAW adds 124 shelves of which 74 hold one part. Inside that, every single SAW and BAW part sits alone: 5 of 5 BAW shelves and 3 of 3 SAW shelves hold exactly one part number. There is no second Walsin candidate for any acoustic filter in the catalogue.

The ranking by stranded share, which is the number a sourcing engineer should care about:

Function	Shelves of one	Share of that function’s shelves
SAW filter	3 of 3	100%
BAW filter	5 of 5	100%
Antenna switch	7 of 8	87.5%
Balun	19 of 32	59.4%
Filter (LTCC)	47 of 84	56.0%
Coupler	3 of 6	50.0%
Multiplexer	14 of 27	51.9%

BA11092442AE1T at 2401~2483MHz and SF11091582GC2T at 1559~1605 MHz are both alone on their shelf, both 1109, both with a single pin convention we cannot check against a datasheet because none exists. The filters look better on raw count — 235 parts — and worse on structure: 47 of 84 filter shelves still hold one part.

Does a second part on the same shelf give you a drop-in second source?

Not on 16 of the 67 multi-part shelves. We checked the Pin Description value of every member of every shelf holding two or more parts. On 16 shelves the members do not share one pin description. 123 of 457 part numbers sit on one of those 16 shelves. A shelf-mate on the same function, type, case size and band can still be a different footprint.

Three examples we read straight out of the files:

Shelf	Parts	Pin description	Match / mismatch
Low pass filter, 1005, 1880~2025 MHz	RFLPF10051G8D7T / RFLPF10051G8D8T	4 / 6-LGA	Mismatch — same band, same size, 4 pins against a 6-pad land grid array
Band pass filter, 2012, 4900-5850 MHz	RFBPF2012090K5T / RFBPF2012100K3T	4 / 4	Match on pins; mismatch on insertion loss, 2.2 dB against 1.8 dB
SPDT antenna switch, 1.1×0.7, 100MHz~6000MHz	RFASWA630PTF0E / RFASWA630PTF0G	6-DFN / 6-QFN	Mismatch — same pin count, different package, 39 dBm against 34 dBm

RFLPF10051G8D7T and RFLPF10051G8D8T are the sharpest case. Same 1005 footprint code, same 1880~2025 MHz passband, same low pass type — and 0.5 dB insertion loss against 1.4 dB, which is 2.8 times the loss. On 19 of the 67 multi-part shelves every member shares one insertion-loss string; on the other 48 they do not. The shelf tells you a candidate exists. It does not tell you the candidate fits.

What actually differs between two baluns sharing the 2012 and 860 to 960 MHz shelf?

Five of nine published fields. RFBLN20120G9D5T and AMBLN2012090B1T are both 2012 LTCC baluns at 860~960 MHz, which is as close as this catalogue gets to a matched pair. Then the balanced impedance doubles, the phase tolerance doubles, and the pin count goes from 6 to 10. Bring your incumbent and fill the third column.

Field	RFBLN20120G9D5T	AMBLN2012090B1T	Your incumbent part	Match / mismatch
Case size	2012	2012	______	Match — same footprint code
Band in export	860~960 MHz	860~960 MHz	______	Match — identical band string
Category	LTCC	LTCC	______	Match — same construction
Application tag	Telecom (2G/3G/4G)	Automotive	______	Mismatch — different intended grade
Unbalanced impedance	50 Ω	50 Ω	______	Match at the single-ended port
Balanced impedance	100 Ω	200 Ω	______	Mismatch — a 2:1 difference, so the matching network changes
Phase difference	180° ± 10°	180° ± 20°	______	Mismatch — twice the phase window
Amplitude difference	0 ± 1 dB	2.5 dB	______	Mismatch — and the two are not even stated in the same form
Insertion loss	1.1 dB	1.3 dB	______	Mismatch — 0.2 dB apart
Pin description	6	10	______	Mismatch — not the same land pattern
Datasheet held by Venatech	none	none	______	Mismatch against any incumbent you hold a datasheet for

We will not tell you a part is equivalent. We will show you where it differs. Here the two parts share a band and a footprint code and disagree on the balanced port, the phase window, the amplitude balance and the pin count — and AMBLN2012090B1T carries an Automotive application tag that Walsin has not qualified in any document we hold.

Which Walsin RF parts have no in-catalogue second candidate at all?

98 part numbers, 21.4% of the line. Those are the parts sitting alone on their shelf: 47 filters, 19 baluns, 14 multiplexers, 7 antenna switches, 5 BAW, 3 SAW and 3 couplers. The remaining 359 parts share a shelf with at least one other Walsin part — but 123 of those 359 sit on a shelf whose members disagree on pin description.

So the useful number for a United States AVL is not 457. Strip out the shelves of one and the footprint mismatches, and the population where an in-catalogue second source is both present and the same land pattern is 236 of 457 part numbers. That is still a real figure and it is still better than most RF lines publish, but it is half the headline.

Nothing in this count says a part is hard to get. We hold no manufacturer’s affected-part list for Walsin or anyone else, and we will never describe a part number, series or family as discontinued or withdrawn. The count is about catalogue structure only.

What can a United States AVL submission actually get for this line?

Less than you want on RF, and we will tell you before you ask rather than after. We hold 28 Walsin datasheets, 451 pages — 26 MLCC series and 2 chip resistor series — sent on request. Zero of those pages cover RF. Across our whole catalogue, 84.2% of 359,135 part numbers have no datasheet; RF’s 457 and antenna’s 44 are at zero.

Eighteen document types appear nowhere in those 451 pages: REACH, SVHC, conflict minerals, PFAS, Prop 65, China RoHS, ISO 9001, IATF 16949, ISO 14001, PPAP, IMDS, VDA, a qualification report, a Declaration of Conformity, a CoC template, CE or UKCA, a PCN policy and a counterfeit policy. Each is not in the documents we hold — a different statement from saying Walsin does not have it. All are on our request list.

What we do supply, and what a supplier-approval questionnaire usually asks for: lot and date-code traceability, a certificate of conformity per shipment on request, and original sealed Walsin packaging. Our authorised distributor status is confirmable with Walsin directly. Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong. (852) 2628 4777.

What should a United States sourcing team do with a 98-of-165 result?

Treat the shelf count as a design input, not a purchasing detail. A part on a shelf of one is a part whose second source has to come from outside Walsin, and that decision is cheaper at schematic review than at production release. Three steps.

1. Cross your whole bill of materials in one pass, free. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool. 18 manufacturers’ part numbers are decoded, against 800,000+ crossable Walsin parts — the exact figure is 871,166 distinct part numbers across 348,669 specification signatures. Filter by commercial or automotive grade and read every stated difference.
2. Ask us which shelf each RF part lands on. We will tell you how many Walsin parts share it, whether they share a pin description, and which fields Walsin publishes on none of them.
3. Check what is physically in Hong Kong on ready stock — a dated snapshot as at 23 September 2026 covering 1,125 part numbers, never a live feed. RF and antenna have zero representation in that snapshot, so plan this line on lead time.

For the method on MLCC, see how to cross-reference an MLCC; for the structure of the RF line itself, Walsin RF balun, filter, coupler and multiplexer. The full line is on the Walsin RF page.

The short version

We sorted all 457 Walsin RF part numbers into 165 shelves by function, published type, case size and band. 98 shelves hold exactly one part and 33 hold exactly two, so 131 of 165 shelves hold two parts or fewer. Every SAW and BAW part sits alone — 3 of 3 and 5 of 5. Of the 67 shelves with two or more parts, 16 contain members with different pin descriptions, covering 123 part numbers, so a shelf-mate is not automatically the same land pattern. The population with a present, same-footprint in-catalogue second candidate is 236 of 457. We hold zero datasheets for the whole line and publish that rather than hide it. Qualification stays with you.

Send us your RF bill of materials and we will return the shelf depth part by part — how many Walsin candidates share each band and footprint, which fields disagree, and which fields Walsin publishes on nobody. And if your second-source policy counts a part as dual-sourced because a part number exists on the same band, how many of your 123 would survive the pin description column?

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Frequently asked questions

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