Everything you need to know about the 4.7pF capacitor: RF matching, crystal oscillator load capacitance, C0G vs X7R dielectric, 0402 vs 0201 package selection, real part numbers, and PCB layout tips for GHz-range designs.

If you’ve spent time designing RF front-ends, crystal oscillator circuits, or high-frequency filters, you’ve almost certainly landed on a 4.7 pF capacitor at some point. It’s one of the most useful values in the sub-10 pF range — large enough to be relatively forgiving in terms of parasitic effects compared to 1 pF, yet small enough to be useful in matching networks and load capacitance tuning well above 1 GHz.

The challenge with a 4.7pF capacitor is that most engineers treat it like any other bypass cap — slap down an X7R MLCC and call it done. That approach works fine at low frequencies, but at RF frequencies it can silently ruin your circuit performance without any obvious component failure. This guide covers the real applications, the specs that actually matter, how to pick the right package, and where to source parts that will perform as expected.

What Is a 4.7 pF Capacitor?

A 4.7 pF capacitor stores 4.7 picofarads of charge — that’s 4.7×10⁻¹² farads. In the standard E12 capacitor series, 4.7 pF falls between 3.9 pF and 5.6 pF. In the E24 series, it sits between 4.3 pF and 5.1 pF. The value is widely stocked in ceramic chip form across multiple package sizes.

At this capacitance level, the reactance (Xc = 1 / 2πfC) at common RF frequencies is:

Frequency	Reactance of 4.7 pF
100 MHz	338 Ω
433 MHz	78 Ω
915 MHz	37 Ω
2.4 GHz	14 Ω
5.8 GHz	5.8 Ω

This reactance range maps directly onto why 4.7 pF shows up in so many RF impedance matching and filter applications between 400 MHz and 3 GHz. At sub-GHz frequencies, it presents a high enough impedance to be useful as a series element; at 2.4 GHz and above, it’s useful as a shunt element in matching networks.

Like all small-value ceramics, a 4.7pF capacitor performs very differently depending on dielectric type, package size, and PCB layout. Understanding those differences is what separates a design that hits spec from one that needs three board respins.

Key Applications of the 4.7 pF Capacitor

RF Impedance Matching Networks

This is the most demanding application for a 4.7pF capacitor. In L-network, pi-network, and T-network matching topologies used to interface antennas, LNAs, PAs, and mixers to a 50 Ω system, the component values are calculated from the source and load impedances and the target center frequency. For frequencies between 400 MHz and 2.4 GHz, calculated capacitance values regularly land in the 2–10 pF range, making 4.7 pF one of the most frequently specified values.

The reactance tolerance matters here. A ±5% tolerance on 4.7 pF means the actual value could be anywhere from 4.47 pF to 4.94 pF. At 2.4 GHz, that’s a reactance variation of roughly ±0.7 Ω — potentially significant in a narrow-band matching network. For production-intent designs, specify ±0.25 pF or ±0.1 pF absolute tolerance.

Crystal Oscillator Load Capacitance

The most common application many digital engineers encounter for a 4.7pF capacitor is in crystal oscillator circuits. A Pierce oscillator (used in virtually all microcontroller crystal circuits) requires two capacitors — one from each oscillator pin to ground — to present the correct load capacitance to the crystal.

For a crystal with a specified load capacitance C_L, the two external caps are ideally:

C_ext = 2 × (C_L − C_stray)

where C_stray accounts for PCB trace capacitance and the MCU pin capacitance (typically 2–5 pF total). For crystals with C_L = 12 pF, C_ext often works out to 12–18 pF per leg after accounting for series parasitic capacitance. But for lower-load-capacitance crystals (C_L = 6–9 pF, increasingly common in low-power and high-frequency crystals), the external capacitors can drop to 4.7 pF or below.

Using the wrong load capacitance shifts the crystal’s operating frequency. For a 32 MHz crystal with a frequency pulling sensitivity of 20 ppm/pF, a 1 pF error in load capacitance causes a 20 ppm frequency error — enough to fail USB timing requirements or cause Bluetooth channel spacing issues.

Antenna Tuning and Matching

Chip antennas for 2.4 GHz (WiFi, BT, Zigbee) and sub-GHz ISM bands almost always require an external matching network to tune the antenna impedance to 50 Ω at the RF IC port. Most chip antenna manufacturers provide a reference matching network in their datasheet, and 4.7 pF is a very common shunt or series element in those networks.

When a PCB is slightly different from the reference design — different board size, different ground plane geometry, different substrate — the antenna impedance shifts and the matching network needs retuning. Having a 4.7 pF cap (or neighboring values like 3.9 pF and 5.6 pF) in your retuning toolkit is standard practice.

RF Filter Design

In discrete LC bandpass, low-pass, and high-pass filters for RF systems, 4.7 pF appears frequently as a shunt or series capacitor in designs for 433 MHz, 868 MHz, 915 MHz, and 2.4 GHz. It’s particularly common in harmonic filters placed after power amplifiers to meet regulatory spurious emission limits.

The Q factor of the capacitor directly affects the filter’s insertion loss and shape factor. A low-Q cap (high ESR) in a filter will add passband insertion loss and round off the filter skirts. For filter applications, specify caps with Q > 200 at the operating frequency.

VCO Tank Circuit Trimming

In voltage-controlled oscillators, the tank circuit capacitance sets the center frequency. A fixed capacitor placed in parallel with the varactor diode (or as part of the tank capacitance) sets the baseline around which the varactor tunes. At 433–915 MHz, these fixed tank caps are often in the 4–10 pF range, making 4.7 pF a natural fit.

High-Speed PCB AC Coupling

In some high-speed differential or RF signal chains, AC coupling capacitors are chosen small enough to maintain a flat response through the operating band while blocking DC. At 2.4 GHz and above, a 4.7 pF coupling cap presents about 14 Ω — low enough to pass the signal with minimal insertion loss while blocking DC offset.

Choosing the Right Package for a 4.7 pF Capacitor

Package selection affects parasitic inductance, parasitic capacitance, self-resonant frequency (SRF), and Q factor. For RF applications, smaller is generally better — up to the point where assembly yield becomes a concern.

Package	Size (mm)	Typical SRF (4.7 pF)	Pad Parasitic C	Best For
0603 (1608M)	1.6 × 0.8	~3–5 GHz	~0.3 pF	General purpose, easy to solder
0402 (1005M)	1.0 × 0.5	~5–8 GHz	~0.15 pF	RF up to 3 GHz, standard RF production
0201 (0603M)	0.6 × 0.3	~8–12 GHz	~0.07 pF	5 GHz and above, lower parasitics
01005 (0402M)	0.4 × 0.2	>12 GHz	<0.05 pF	mmWave, specialized assembly only

For most RF work at 433 MHz to 3 GHz, 0402 is the right choice. It balances low parasitics with practical assembly requirements. Move to 0201 if you’re designing above 3 GHz or if you’re doing a comparative placement trial to measure layout parasitics.

Dielectric Selection: Why C0G Is Non-Negotiable for RF

This is one of the most common specification errors on RF PCBs. There are three main MLCC dielectric classes you’ll encounter:

Dielectric	Capacitance Stability vs Temp	Capacitance vs Voltage	Use in RF Circuits
C0G (NP0)	±30 ppm/°C (excellent)	No change	Yes — always preferred
X7R	±15% over −55 to +125°C	Degrades with DC bias	Avoid for RF/oscillator use
Y5V	+22% / −82% over temp range	Severely degrades with bias	Never use in RF circuits

For a 4.7pF capacitor in a matching network or oscillator circuit, C0G (NP0) is the only acceptable dielectric. X7R capacitance drifts by up to 15% over temperature — for a 4.7 pF cap, that’s a swing of nearly 0.7 pF, which will detune your matching network and pull your oscillator frequency. C0G caps cost a bit more, but the difference is negligible in any RF design where performance matters.

Recommended 4.7 pF Capacitor Part Numbers

Manufacturer	Part Number	Package	Dielectric	Tolerance	Voltage
Murata	GRM1555C1H4R7BA01D	0402	C0G	±0.1 pF	50 V
TDK	C1005C0G1H4R7C050BA	0402	C0G	±0.25 pF	50 V
Kemet	C0402C479C5GACTU	0402	C0G	±0.25 pF	50 V
Vishay	VJ0402A4R7CXACW1BC	0402	C0G	±0.1 pF	50 V
Würth Elektronik	885012005017	0402	C0G	±0.1 pF	50 V
AVX/Kyocera	04025A4R7BAT2A	0402	C0G	±0.1 pF	50 V
ATC	100B4R7BW500XT	ATC 100B	C0G	±0.1 pF	500 V

The ATC 100B series is worth calling out specifically for high-power RF applications (PA harmonic filters, antenna switches) where a standard MLCC would fail under RF current stress. The capacitor construction in these high-Q RF chip caps is fundamentally different from standard MLCCs.

PCB Layout Guidelines for 4.7 pF Capacitors in RF Circuits

Use the manufacturer’s recommended land pattern. Pad dimensions directly affect parasitic capacitance. An oversized 0402 pad pattern can add 0.1–0.3 pF of stray capacitance — up to 6% of your intended 4.7 pF value.

Consider a ground plane void beneath series capacitors. For caps placed in a series RF signal path, a small copper void (clearance cutout) in the ground plane beneath the cap reduces parasitic shunt capacitance to ground. This is especially important at 2.4 GHz and above.

Keep matching network components close together and close to the antenna or RF port. Trace length between matching elements adds inductance and changes the network’s effective topology. Route matching caps with the shortest possible traces directly to the pad.

Run EM simulation before fabrication. At 2.4 GHz and above, even the shape of your pad and the trace routing around a 4.7 pF cap can shift the effective capacitance enough to detune a matching network. Sonnet Lite (free), Ansys HFSS, or Cadence AWR can extract parasitic effects from your layout before committing to fab.

Separate matching network ground vias from digital return currents. A single via shared between the matching network ground and a switching regulator return path can inject noise into the RF circuit. Keep RF ground returns isolated and stitched directly to the RF ground plane.

Where to Buy 4.7 pF Capacitors

Distributor	Website	Notes
Digi-Key	digikey.com	Best parametric search, huge stock depth
Mouser	mouser.com	Strong authorized stock for Murata, TDK, KEMET
LCSC	lcsc.com	Cost-effective for prototyping quantities
Arrow	arrow.com	Good for production volumes with traceability
Farnell/Element14	farnell.com	EU/UK preferred distributor for authorized stock

For production runs, always buy through authorized distributors with full traceability. Counterfeit small-value ceramics are more common than most engineers expect, and the failure mode is insidious — the fake caps often measure close to spec on an LCR meter but perform poorly at RF frequencies due to inferior dielectric or electrode materials.

Useful Resources and Design Tools

• Murata SimSurfing – Free online tool to view impedance, ESR, and S-parameters vs. frequency for Murata capacitors: ds.murata.com/simsurfing
• Kemet KSIM – Capacitor simulation with impedance and insertion loss curves: ksim.kemet.com
• TDK Product Finder with S-parameter Downloads – Full parametric search with downloadable SPICE/S-param models: product.tdk.com
• ATC RF Capacitor Datasheet Library – High-Q RF chip caps with full S-parameter data for microwave design: atceramics.com
• Sonnet Lite (Free EM Simulator) – Layout-level EM simulation for RF circuits: sonnetsoftware.com
• Texas Instruments Crystal Oscillator Design Reference (AN-2447) – Detailed guide on load capacitance calculation for Pierce oscillators
• Würth Elektronik ANP008 – Application note on three-terminal caps, RF filtering, and parasitic effects: we-online.com
• Mini-Circuits RF Calculators – L-network and pi-network matching calculators: minicircuits.com

Frequently Asked Questions About 4.7 pF Capacitors

Can I substitute a 4.7 pF capacitor with 4.3 pF or 5.1 pF in a matching network?

Often yes — with simulation and measurement. In an RF matching network, the center frequency and impedance transformation depend on the exact component values. Swapping 4.7 pF for 4.3 pF or 5.1 pF will shift the network’s response, but depending on the bandwidth of the network, the change may be tolerable. Always re-simulate with the new value and verify on hardware with a VNA before committing to the change in production.

Why does my 4.7 pF capacitor measure differently on my LCR meter than its spec?

Low-value capacitors are sensitive to measurement frequency, lead placement, and stray capacitance in the test fixture. Most LCR meters measure at 1 kHz or 1 MHz by default, which may not match the frequency at which the cap was characterized in its datasheet. Also, probe leads and the PCB itself contribute parasitic capacitance that can add 0.5–1 pF or more to the reading. Open-compensation and short-compensation in the LCR meter’s fixture calibration helps, but some residual error is unavoidable at 4.7 pF.

What happens if I use X7R instead of C0G for a 4.7 pF cap in an oscillator circuit?

You’ll likely see oscillator frequency drift with temperature that exceeds the crystal’s own temperature coefficient. X7R capacitance can change by ±15% over the operating temperature range. For a 4.7 pF cap, that’s up to ±0.7 pF variation. In a crystal load capacitance context, a 1 pF change in total load capacitance can pull the oscillator frequency by 10–30 ppm depending on the crystal’s motional parameters — enough to cause real problems in wireless or USB clock applications. Use C0G.

How do I account for PCB parasitic capacitance when placing a 4.7 pF cap?

Start by estimating the parasitic contribution from your layout: typical 0402 pad pair adds ~0.1–0.2 pF, a short trace to a via adds ~0.1–0.3 pF/mm, and a via itself adds ~0.3–0.8 pF depending on board stackup and aspect ratio. Sum these up and subtract from your target capacitance to get the component value you actually need to specify. If the parasitics are comparable to your intended 4.7 pF, use EM simulation to get a more accurate parasitic estimate before ordering parts.

Is a 4.7 pF capacitor suitable for power supply decoupling?

Technically yes, but it’s generally too small to be useful as a standalone decoupling cap in any power supply context. At 100 MHz, a 4.7 pF cap presents about 338 Ω — far too high for effective high-frequency decoupling. You’d use 100 nF or 10 nF for bulk and high-frequency decoupling, and possibly a 1–10 pF cap only as a supplementary high-frequency bypass in very specific RF power supply situations. In standard digital or analog power supply design, a 4.7 pF cap has no practical decoupling role.

Working with a 4.7pF capacitor well comes down to three things: specifying C0G dielectric every single time, choosing the right package for your frequency range, and respecting the role that PCB layout plays at values this small. Get those right and a 4.7 pF cap in a matching network or oscillator circuit will hit your targets. Get them wrong and you’ll spend debugging time on a problem that was never really a circuit topology issue in the first place.