A Walsin Technology (Walsin) chip attenuator part number reads WA04P, then the
attenuation in decibels, then X, then a letter for the attenuation accuracy, then TL.
WA04P010XCTL is a 0402 Pi-type attenuator at 10 dB into 50 ohms with ±0.4 dB accuracy.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 23 parts.
What is a chip attenuator?
A chip attenuator is a fixed resistive network in a single surface mount package that
reduces signal amplitude by a defined number of decibels while presenting a defined
impedance at both ports. Walsin’s parts are Π-type networks — one series resistor with a
shunt resistor at each end — built into a 0402 chip.
The point of a network rather than a single resistor is impedance. A lone series resistor
attenuates, but it also changes the impedance seen from either side, which spoils the match.
A Π network attenuates by a set amount and looks like 50 Ω from both ports at once.
Typical uses are pad insertion ahead of a mixer or amplifier input, improving return loss on
a poorly matched port, and setting drive level into a power amplifier stage. Walsin’s whole
range is 23 parts — a small, complete set, not a series group you need to filter.
How do I read a Walsin chip attenuator part number?
Six fields in twelve characters. WA04P010XCTL splits as WA for the chip network family,
04 for 0402 (1005), P for the Π-type attenuator type code, 010 for 10 dB, X for the
network configuration, C for ±0.4 dB accuracy, T for 7-inch reel taping and L for Sn
base lead-free termination.
| Field | Characters | Value in WA04P010XCTL |
What it means |
|---|---|---|---|
| Family | 1–2 | WA |
Walsin chip network family — shared with the resistor arrays |
| Size code | 3–4 | 04 |
0402 (1005) — the only size in the range |
| Type code | 5 | P |
Π-type chip attenuator |
| Attenuation | 6–8 | 010 |
10 dB |
| Configuration | 9 | X |
Present on all 23 parts |
| Accuracy | 10 | C |
±0.4 dB |
| Packaging | 11 | T |
7″ reel taping |
| Termination | 12 | L |
Sn base (lead free) |
The attenuation field is the one that needs care. Whole numbers use three digits with
leading zeros: 001 is 1.0 dB, 010 is 10 dB, 020 is 20 dB. Half-decibel values use R
as the decimal point in the first position, so R05 is 0.5 dB and R15 is 1.5 dB.
So WA04P001XBTL is 1.0 dB and WA04PR15XBTL is 1.5 dB. Reading R15 as “15 dB” is the
mistake this format invites, and 15 dB is WA04P015XFTL.
What does the letter before TL mean?
Attenuation accuracy in decibels, and it is not a free choice — it is determined by the
attenuation value. Walsin’s accuracy band widens as the attenuation rises, from ±0.1 dB at
0.5 dB of loss to ±2.5 dB at 20 dB of loss. One letter per band, nine bands across
23 parts.
| Accuracy letter | Attenuation accuracy | Attenuation values it covers | Parts held |
|---|---|---|---|
P |
Not specified | 0 dB | 1 |
A |
±0.1 dB | 0.5 dB | 1 |
B |
±0.3 dB | 1.0, 1.5, 2.0, 3.0, 4.0, 5.0 dB | 6 |
C |
±0.4 dB | 6.0, 7.0, 8.0, 9.0, 10 dB | 5 |
D |
±0.8 dB | 11, 12, 13 dB | 3 |
E |
±1.0 dB | 14 dB | 1 |
F |
±1.5 dB | 15, 16 dB | 2 |
G |
±2.0 dB | 17, 18, 19 dB | 3 |
H |
±2.5 dB | 20 dB | 1 |
There is exactly one 20 dB part and its accuracy is ±2.5 dB, so the real attenuation of a
WA04P020XHTL sits between 17.5 dB and 22.5 dB. If a design needs 20 dB to better than a
decibel, two cascaded 10 dB pads is the tighter arrangement.
That trade-off is the most useful thing in this table. Cascading WA04P010XCTL twice gives
20 dB nominal with the two ±0.4 dB tolerances stacking to ±0.8 dB worst case, against
±2.5 dB for the single 20 dB part. The cost is an intermediate node that has to stay 50 Ω.
Because the accuracy letter is fixed by the attenuation value, you cannot order a tighter
grade of the same value.
Why does a parametric search for a resistance value never find a chip attenuator?
Because Walsin’s export puts a decibel figure in the Resistance column, an impedance in
the Tolerance column and a decibel accuracy in the TCR column. Every numeric filter a
buyer would reach for is pointed at a field holding the wrong quantity.
| Column in Walsin’s export | What it holds on a normal chip resistor | What it holds on a chip attenuator | Match / mismatch |
|---|---|---|---|
Resistance |
Ohms, e.g. 10000Ω |
Decibels, e.g. 10dB |
Mismatch — no numeric ohm value exists to filter on |
Tolerance |
Percent, e.g. ±1% |
Port impedance, 50Ω on 22 parts, Jumper on 1 |
Mismatch — the impedance is in the tolerance field |
TCR |
ppm/°C, e.g. ≦±200 |
Attenuation accuracy, e.g. ±0.4dB |
Mismatch — no temperature coefficient is published |
Rated Power |
Watts | 1/10W on all 23 parts |
Match — this field behaves normally |
Size |
Case code | 0402(1005) on all 23 parts |
Match — this field behaves normally |
Packaging |
Reel format | 7" reel taping on all 23 parts |
Match — this field behaves normally |
Unique to Venatech’s data. All 23 Walsin chip attenuators put a decibel value in the
Resistancecolumn and the 50 Ω port impedance in theTolerancecolumn, with the
attenuation accuracy in theTCRcolumn. Not one of the 23 rows carries a resistance in
ohms. A parametric search for an ohm value, a percentage tolerance or a ppm/°C coefficient
returns zero attenuators, and the entire range is invisible to anyone filtering
numerically. Measured across Walsin’s own chip resistor export; not published anywhere.
The workaround is to search on the series group name or on the WA04P prefix.
None of the 23 part numbers contains an embedded space. The attenuator group is one of only
three chip resistor series groups in Venatech’s extract where no part number carries a space;
across the whole 234,815-part extract, 39,576 do.
What attenuation values does Walsin offer, and in what case size?
23 values from 0 dB to 20 dB, all at 0402 (1005), all 50 Ω, all rated 1/10 W. The steps are
0, 0.5, 1.0, 1.5, then whole decibels from 2 to 20. There is no 0402 gap and there is no
other case size.
| Part number | Attenuation | Port impedance | Accuracy | Size | Rated power |
|---|---|---|---|---|---|
WA04P000XPTL |
0 dB | Jumper |
Not specified | 0402 (1005) | 1/10 W |
WA04PR05XATL |
0.5 dB | 50 Ω | ±0.1 dB | 0402 (1005) | 1/10 W |
WA04P001XBTL |
1.0 dB | 50 Ω | ±0.3 dB | 0402 (1005) | 1/10 W |
WA04PR15XBTL |
1.5 dB | 50 Ω | ±0.3 dB | 0402 (1005) | 1/10 W |
WA04P003XBTL |
3.0 dB | 50 Ω | ±0.3 dB | 0402 (1005) | 1/10 W |
WA04P006XCTL |
6.0 dB | 50 Ω | ±0.4 dB | 0402 (1005) | 1/10 W |
WA04P010XCTL |
10 dB | 50 Ω | ±0.4 dB | 0402 (1005) | 1/10 W |
WA04P013XDTL |
13 dB | 50 Ω | ±0.8 dB | 0402 (1005) | 1/10 W |
WA04P014XETL |
14 dB | 50 Ω | ±1.0 dB | 0402 (1005) | 1/10 W |
WA04P016XFTL |
16 dB | 50 Ω | ±1.5 dB | 0402 (1005) | 1/10 W |
WA04P019XGTL |
19 dB | 50 Ω | ±2.0 dB | 0402 (1005) | 1/10 W |
WA04P020XHTL |
20 dB | 50 Ω | ±2.5 dB | 0402 (1005) | 1/10 W |
The 1/10 W rating is the one to check against the application. A pad ahead of a receiver
front end handles microwatts. A pad on a transmitter output is different: 1/10 W is 20 dBm,
and a 10 dB pad absorbs 90% of the incident power.
Work it the other way. A 10 dB pad dissipating no more than 1/10 W can accept about 111 mW
in, since 10% passes through — roughly 20.5 dBm. Walsin’s range offers nothing above that.
Is the 0 dB part an attenuator at all?
Electrically it is a through connection. WA04P000XPTL carries 0dB in the attenuation
field and Jumper where every other part carries 50Ω. Its accuracy field is -. It is
the placeholder that lets one footprint be either a pad or a link.
That is genuinely useful. Lay down one attenuator footprint, populate it with
WA04P000XPTL for the first build, and if the level turns out wrong, change one line of the
BOM rather than one layer of the board.
The P accuracy letter marks it. Walsin uses P for jumper parts across the chip resistor
catalogue — the general purpose 0 Ω jumper WR04X000 PTL carries the same letter in the same
role.
One caution. A 0 Ω jumper and a 0 dB attenuator are not the same object. Ask Venatech for the
attenuator drawing before assuming the internal routing matches the path you have drawn.
How does a chip attenuator differ from a resistor array with the same WA prefix?
The WA prefix is shared. Venatech’s extract holds 5,887 parts beginning WA: 5,864 thick
film chip resistor arrays and the 23 attenuators. The type code in position five separates
them — P is the attenuator, while X, Y, T, W, F and G are array
configurations.
| Part number | Series group | Size | Value field | Second field | Accuracy / tolerance | Match / mismatch vs WA04P010XCTL |
|---|---|---|---|---|---|---|
WA04P010XCTL |
Chip Attenuator (Convex, Π type) | 0402 (1005) | 10dB |
50Ω impedance |
±0.4 dB | Reference part |
WA04X1002FTL |
Thick Film Chip Resistor Array | 0402 (1005) | 10000Ω |
±1% tolerance | ≦±200 ppm/°C | Prefix and size match — type code, value units and every other field mismatch |
WA04Y10R0FTL |
Thick Film Chip Resistor Array | 0402 (1005) | 10Ω |
±1% tolerance | ≦±200 ppm/°C | Prefix and size match — type code, value units and every other field mismatch |
WA04X000 PTL |
Thick Film Chip Resistor Array | 0402 (1005) | 0Ω |
Jumper |
Not specified | Prefix, size and jumper role match — a resistor link, not an attenuator |
WA04P000XPTL |
Chip Attenuator (Convex, Π type) | 0402 (1005) | 0dB |
Jumper |
Not specified | Series group, size and jumper role match — attenuation instead of resistance |
The 0402(1005) in the array rows is the size of the element, not the package. A
WA04X… part is a four-element array of 0402-sized resistors in a single larger body; a
WA04P… attenuator is one 0402 package.
What is a Pi-type attenuator, and does Walsin list a T-type?
A Π-type attenuator is a shunt resistor to ground, a series resistor, and a second shunt
resistor to ground — three elements in the shape of the Greek letter. Walsin’s series group
is named Chip Attenuator (Convex, Π type) and all 23 parts sit in it. No T-type appears in
the data Venatech holds.
Π and T networks can both give the same attenuation at the same port impedance; the choice
is about the resistor values that fall out.
“Convex” in the series group name describes the terminal geometry, the same word Walsin
uses across its chip resistor array range. It is a package descriptor, not an electrical one.
For the record, the complete Walsin chip attenuator range as Venatech holds it is:
WA04P000XPTL, WA04PR05XATL, WA04P001XBTL, WA04PR15XBTL, WA04P002XBTL,
WA04P003XBTL, WA04P004XBTL, WA04P005XBTL, WA04P006XCTL, WA04P007XCTL,
WA04P008XCTL, WA04P009XCTL, WA04P010XCTL, WA04P011XDTL, WA04P012XDTL,
WA04P013XDTL, WA04P014XETL, WA04P015XFTL, WA04P016XFTL, WA04P017XGTL,
WA04P018XGTL, WA04P019XGTL and WA04P020XHTL. Twenty-three parts, one size, one
impedance.
FAQ
What does WA04P mean on a Walsin part number?
WA is Walsin’s chip network family prefix, shared with the thick film resistor arrays. 04 is the 0402 (1005) case size. P is the type code for the Π-type chip attenuator. All 23 Walsin chip attenuators begin WA04P, and no other series group uses that five-character combination.
How do I tell 1.5 dB from 15 dB in a Walsin attenuator part number?
By the R. Half-decibel values put R in the first of the three attenuation characters, so 1.5 dB is WA04PR15XBTL. Whole decibels use three digits with leading zeros, so 15 dB is WA04P015XFTL. The accuracy letter differs too — B for ±0.3 dB against F for ±1.5 dB.
What is the letter before TL on a chip attenuator?
The attenuation accuracy. A is ±0.1 dB, B is ±0.3 dB, C is ±0.4 dB, D is ±0.8 dB, E is ±1.0 dB, F is ±1.5 dB, G is ±2.0 dB and H is ±2.5 dB. P marks the 0 dB jumper. The letter is set by the attenuation value and cannot be chosen independently.
What impedance are Walsin chip attenuators?
50 Ω, on all 22 attenuating parts. The impedance is not encoded in the part number; it appears in the Tolerance column of Walsin’s export rather than in a dedicated field. The 23rd part, WA04P000XPTL, is the 0 dB jumper and carries Jumper in that column instead.
What attenuation range does Walsin cover?
0 dB to 20 dB in 23 steps: 0, 0.5, 1.0, 1.5, then every whole decibel from 2 to 20. Every part is 0402 (1005) and rated 1/10 W. There is no part above 20 dB and no second case size. For higher attenuation, cascade two pads and stack the tolerances.
Why can I not find chip attenuators in a parametric search?
Because the numeric fields hold the wrong quantities. The Resistance column holds decibels, the Tolerance column holds the 50 Ω port impedance and the TCR column holds the decibel accuracy. No attenuator row carries a resistance in ohms, so an ohm-value filter returns none of them.
Is 20 dB in one part better than two 10 dB pads?
Not on accuracy. The single 20 dB part WA04P020XHTL is specified to ±2.5 dB. Two WA04P010XCTL pads at ±0.4 dB each stack to ±0.8 dB worst case for the same nominal attenuation. The cascade costs a second component and an intermediate 50 Ω node that must stay matched.
Does Walsin make a T-type chip attenuator?
Not in the data Venatech holds. All 23 parts sit in the series group Chip Attenuator (Convex, Π type). If a T-type is needed, ask Venatech to raise it with Walsin rather than assuming a Π part can be substituted, because the internal node arrangement differs even when the port behaviour matches.
Next step
The attenuator range is small enough to specify in one pass, and the accuracy letter does
the specifying. Send the attenuation, the port impedance and the accuracy you need, and
Venatech Limited, an authorised Walsin distributor in Hong Kong, will return the exact part
number, the accuracy band that comes with it, and whether a cascade of two pads is the
tighter answer.
Send your BOM to Venatech · Browse the
Walsin chip resistor range, which is where Walsin files the
attenuator data · Read
Chip resistor arrays explained and
Walsin RF: balun, filter, coupler, multiplexer.
Cross it yourself. The cross-reference tool takes a single part number or a whole BOM column and returns the Walsin candidates with every field that differs stated plainly — qualification stays with you. Ready stock shows what is held in Hong Kong today, with an RFQ against any line.