Learn what a C0G capacitor (NP0) is, how it differs from X7R, and exactly when to use it in RF, timing, and precision circuits — with tables, specs, and FAQs.

If you’ve spent any time sourcing components or reviewing a BOM, you’ve almost certainly run into the term C0G capacitor — sometimes written as NP0 — and wondered whether it actually matters which type you specify. The short answer from any seasoned PCB engineer: yes, it absolutely does. Choose the wrong dielectric and you can watch a timing circuit drift, an oscillator wander off frequency, or an RF filter’s response shift unexpectedly with temperature. This guide breaks down everything you need to know about the C0G capacitor, how it compares to the alternatives, and exactly when it belongs on your board.

What Is a C0G Capacitor?

A C0G capacitor is a type of multilayer ceramic capacitor (MLCC) that uses a Class I dielectric material. The “C0G” designation follows the EIA (Electronic Industries Alliance) standard coding system. The name might look strange at first — that middle character is a zero, not the letter O — but once you break it down, the code makes sense:

• C = the significant figure of the temperature coefficient (in this case, 0 ppm/°C)
• 0 = the multiplier (×1)
• G = the tolerance on the temperature coefficient (±30 ppm/°C)

Put it together and you get a capacitor whose capacitance changes by no more than ±30 ppm per degree Celsius across the full operating range of −55°C to +125°C. That works out to less than ±0.3% capacitance change across that entire span. For a passive component, that is exceptional stability.

C0G vs NP0 — Are They the Same Thing?

Yes, C0G and NP0 refer to the same component. NP0 comes from the U.S. Military Standard (MIL-SPEC) naming convention, where the letters stand for Negative-Positive-Zero — meaning the capacitance does not shift in either the negative or positive direction as temperature changes. C0G is the EIA equivalent. European datasheets often print it as NPO (with a letter O), but the correct rendering uses a zero. Both terms refer to the same Class I ceramic dielectric, and you can use them interchangeably when ordering or specifying parts.

How C0G Capacitors Are Made

Class I ceramic capacitors like C0G use non-ferroelectric (paraelectric) formulations for their dielectric material, primarily based on strontium zirconate (SrZrO₃) or titanium dioxide (TiO₂), with various dopants added to fine-tune the temperature coefficient. Modern C0G formulations often incorporate neodymium, samarium, and other rare earth oxides. The non-ferroelectric nature of the material is the key: it does not polarize the way barium titanate (the basis for X7R and X5R) does, which is exactly what gives C0G its near-zero voltage coefficient and outstanding aging characteristics.

Key Electrical Characteristics of C0G Capacitors

Understanding what makes a C0G capacitor tick helps you know where to deploy it and where a cheaper alternative will do just fine.

Parameter	C0G / NP0	X7R	X5R	Y5V
Dielectric Class	Class I	Class II	Class II	Class II
Temperature Range	−55°C to +125°C	−55°C to +125°C	−55°C to +85°C	−30°C to +85°C
Capacitance Change vs Temp	±30 ppm/°C (< ±0.3%)	±15%	±15%	+22% / −82%
Voltage Coefficient	None	Significant	Significant	Severe
Aging	None	Yes	Yes	Yes
Typical Capacitance Range	0.5 pF to ~100 nF	Up to 10 µF+	Up to 47 µF+	Up to 100 µF+
Typical Tolerance	±0.5 pF, ±1%, ±2%, ±5%	±10%, ±20%	±10%, ±20%	±20%
Piezoelectric Effect	None	Present	Present	Present
Relative Cost	Higher	Medium	Medium	Low
Package Size for Same Value	Larger	Medium	Smaller	Smallest

Temperature Stability

Capacitance drift or hysteresis for C0G ceramics is negligible at less than ±0.05%, versus up to ±2% for film capacitors. Typical capacitance change over the service life of a C0G part is less than ±0.1% — one-fifth that shown by most other dielectrics. For engineers working on products that need to maintain spec over years of field use across wide temperature swings, that is not a trivial advantage.

No Voltage Coefficient

This one trips up a lot of engineers who are used to working only with X7R or X5R. A critical warning with Class II capacitors: they lose capacitance as DC voltage is applied. A 10 µF X7R capacitor rated for 16 V might only act like a 2 µF capacitor when 12 V is applied. The C0G capacitor has essentially no voltage coefficient. The value you see on the datasheet is the value you get, regardless of what DC bias is sitting across it.

No Aging

Ferroelectric materials undergo domain reorientation over time, which causes Class II capacitors to slowly lose capacitance after manufacture. C0G has no such aging mechanism. C0G formulations show no aging characteristics. This is particularly important for applications in medical devices, industrial instrumentation, and aerospace — anywhere you need performance to remain consistent years after production.

No Piezoelectric Effect

Class 2 caps exhibit piezoelectric behavior that can cause them to function as both microphones (converting sound into electrical noise) and buzzers (converting AC signals into audible noise). Class 1 capacitors don’t have this problem. In audio circuits and noise-sensitive analog designs, this difference is audible and measurable.

High Q Factor

C0G formulations typically have a Q factor in excess of 1000 and show little capacitance or Q changes with frequency. Dielectric absorption is typically less than 0.6%, comparable to mica and most film capacitors. High Q means low dielectric losses, making C0G well-suited for resonant circuits where energy dissipation must be minimized.

Decoding the EIA Code for Class I Ceramics

The Class I temperature characteristic code follows a three-character letter-number-letter format. This is separate from the Class II coding system (X7R, X5R, etc.) because Class I dielectrics use parts-per-million tolerances rather than percentage tolerances.

Code Character	Position	Meaning
C	1st (letter)	Significant figure = 0 ppm/°C
0	2nd (number)	Multiplier = ×1
G	3rd (letter)	Tolerance = ±30 ppm/°C

For reference, related Class I codes you may encounter:

EIA Code	MIL Equivalent	Temp Coefficient
C0G	NP0	0 ±30 ppm/°C
U2J	N750	−750 ±120 ppm/°C
S2H	N330	−330 ±60 ppm/°C
R2H	N150	−150 ±60 ppm/°C

The C0G / NP0 combination is by far the most widely used Class I ceramic in modern designs.

When to Use a C0G Capacitor

This is the practical meat of the matter. After years of designing boards, the mental model that works best is this: reach for C0G any time the exact capacitance value matters to how your circuit works. Here is a breakdown by application type.

Timing Circuits and RC Oscillators

Timing circuits are highly sensitive to capacitance variations. Any change in capacitance directly affects the timing period. In RC timing circuits, T = RC — if C changes, T changes. Using an X7R in an RC timing network that needs to hold its period across temperature is asking for trouble. The 15% capacitance change over temperature in X7R and the voltage coefficient can introduce unacceptable timing errors. Always use C0G for the capacitors in any RC timing network that needs to hold spec.

Crystal Oscillator Load Capacitors

High-precision crystal oscillators such as OCXOs and TCXOs require extremely stable load capacitance. X7R capacitors would introduce unacceptable frequency drift — C0G is essential here. Even small deviations in load capacitance shift the crystal’s resonant frequency. C0G is the only sensible choice.

RF Circuits and Impedance Matching Networks

In RF design, a capacitor that shifts value with temperature changes the impedance match. A poorly matched PA stage loses output power and efficiency; a mismatched LNA degrades noise figure. By optimizing the design, RF capacitors using C0G/NP0 dielectrics can be made with a frequency response up to 3 GHz. If you are designing anything above 10 MHz where component stability is part of the specification, C0G is the default choice for resonant and matching components.

Phase-Locked Loops (PLLs)

C0G is often used in critical PLL components such as feedback network capacitors where frequency stability is paramount. A drifting capacitor in the loop filter of a PLL will change the loop bandwidth and phase margin — causing anything from subtle jitter increases to outright instability.

Precision Analog Filters

Active and passive filters designed to specific cutoff frequencies will drift if the capacitors drift. In test and measurement equipment, medical instrumentation, or precision ADC front ends, that drift is often unacceptable. C0G keeps the filter corners exactly where you put them.

Audio Circuits (Signal Path)

The zero piezoelectric effect of C0G becomes a real advantage in audio. Ceramic capacitors in the signal path of a high-quality audio design can act as microphones, picking up mechanical vibrations from nearby transformers or speakers and injecting them as noise. C0G capacitors are immune to this effect.

Applications Where C0G Is Probably Overkill

Being honest here matters too. X7R is perfectly fine — and more practical — for decoupling and bypass capacitors on power rails, where the exact capacitance value is not critical. Bulk energy storage, general coupling in non-precision signal paths, and EMI filtering at the power entry point are all scenarios where the extra cost and larger footprint of C0G do not buy you anything meaningful.

C0G Capacitor Limitations You Need to Know

Limited Capacitance Range

This is the biggest practical constraint. C0G does not have good volumetric efficiency — searching for a 0.1 µF C0G cap, the smallest in-stock part is typically a 1206. In contrast, a 0.1 µF X7R cap is available in the 0306 package with a 10 V rating. C0G capacitors are rarely available above 100 nF in reasonable package sizes, and finding values above 10 nF in compact 0402 or 0603 packages can be difficult and expensive.

Larger Physical Size

The non-ferroelectric dielectric has a lower dielectric constant than barium titanate, which means more physical volume is needed to achieve the same capacitance. When board space is tight, this trade-off must be weighed against the precision benefit.

Higher Cost

For high-capacitance values, C0G parts are significantly more expensive than equivalent X7R. For small values (a few pF to a few nF), the cost difference is minimal and rarely worth optimizing around.

C0G vs X7R: A Head-to-Head Comparison for PCB Engineers

Scenario	Best Choice	Why
Crystal load capacitors	C0G	Frequency accuracy is paramount
RC timing circuit	C0G	Capacitance drift = timing drift
RF matching network (>10 MHz)	C0G	Impedance stability required
PLL loop filter	C0G	Bandwidth and phase margin stability
Power rail decoupling (100 nF)	X7R	Value stability not critical
Bulk bypass (1 µF+)	X5R / X7R	C0G not available in these values
Audio signal path coupling	C0G	No piezoelectric effect
Gate drive snubber	X7R	High capacitance needed, stability less critical
Low-frequency EMI filter	X7R or X5R	Size and cost dominate

The rule of thumb from experienced engineers: never compromise on C0G for critical timing or RF circuits. For everything else, evaluate whether the stability actually matters before specifying it.

How to Select a C0G Capacitor: Practical Checklist

When you are picking a C0G capacitor for your design, run through these parameters:

1. Capacitance Value and Tolerance C0G is available in very tight tolerances — ±0.25 pF, ±0.5 pF, ±1%, ±2%, and ±5% are all common. For oscillator load caps, ±1% or tighter is usually the right call.

2. Voltage Rating Always derate. A good rule of thumb is to operate at no more than 50% of the rated voltage, especially for smaller package sizes.

3. Package Size Check the available inventory for your target value. You may find that the value you want is only available in 0805 or 1206 in C0G, which forces a board layout reconsideration.

4. Temperature Range C0G covers −55°C to +125°C as standard. If your application goes to 150°C or 175°C, look for high-temperature rated versions from manufacturers like KYOCERA AVX (their AT Series is rated to 200°C and 250°C).

5. Self-Resonant Frequency For RF applications, verify that the self-resonant frequency of the capacitor is well above your operating frequency. At resonance, the component is inductive rather than capacitive.

6. ESR C0G capacitors have low ESR, which is an advantage in resonant circuits but worth verifying against manufacturer simulation tools for RF work.

Identifying C0G vs X7R on an Assembled Board

A common manufacturing QA concern: how do you tell them apart visually after placement? A practical tip: C0G/NP0 capacitors have a grey body color, while X7R capacitors are brown. This is not universally standardized across all manufacturers, but it is a useful first-pass check when auditing a board or investigating a substitution.

Useful Resources for C0G Capacitor Selection

Here are reliable databases and tools to help with C0G capacitor selection and simulation:

Resource	What It Offers	Link
Murata SimSurfing	Impedance simulation, S-parameter data for Murata MLCCs	murata.com/tool/simsurfing
KYOCERA AVX SpiMLCC	Frequency response and voltage coefficient simulation for AVX parts	kyocera-avx.com
Kemet KSIM	Spice models and frequency response simulation for Kemet capacitors	kemet.com/ksim
TDK Product Center	Temperature characteristic FAQs, parametric search, datasheets	product.tdk.com
DigiKey Parametric Search	Filter by dielectric, capacitance, package, tolerance	digikey.com
Mouser Electronics	Wide C0G inventory with filtering by manufacturer	mouser.com
IPC-7711/7721	Rework and repair standard referencing component classifications	Via IPC.org

For a broader understanding of how capacitors fit into PCB design — including footprint choices, placement strategy, and decoupling hierarchies — the PCB capacitor guide at RayPCB covers the topic from a layout and manufacturing perspective.

Frequently Asked Questions About C0G Capacitors

1. Can I substitute an X7R capacitor for a C0G in an oscillator circuit?

Not if timing or frequency accuracy matters. The ±15% capacitance change over temperature in X7R versus ±0.3% in C0G translates directly to frequency drift. In a crystal oscillator, even a ±1% change in load capacitance shifts the output frequency by a measurable amount. For a simple RC relaxation oscillator where ±5% timing accuracy is fine, X7R might be acceptable — but for anything tighter, stick with C0G.

2. Why can’t I find C0G capacitors larger than 100 nF?

It comes down to the dielectric constant. C0G uses a non-ferroelectric material with a dielectric constant (relative permittivity) typically in the range of 20–50. X7R uses barium titanate with a dielectric constant of 1,000–3,000. Higher dielectric constant means more capacitance per unit volume. To reach 1 µF in C0G, you would need a very large physical package that is not practical for SMT assembly. That is why X7R and X5R own the high-capacitance space.

3. Does a C0G capacitor degrade with DC bias voltage?

No. This is one of the defining advantages of a C0G capacitor. The capacitance value does not shift with applied DC voltage. Class II capacitors (X7R, X5R, Y5V) can lose anywhere from 20% to 80% of their rated capacitance under DC bias, which is a well-known but often underappreciated trap in circuit design.

4. What is the difference between C0G and NP0 — should I specify one over the other?

Electrically they are equivalent. C0G is the EIA-standard code; NP0 is the MIL-SPEC and common industry term. On a BOM, you can specify either. Some manufacturers, including TDK, use both codes to differentiate slight variations in operating temperature range within their product lines, so it is worth double-checking the datasheet if you are sourcing from a single vendor for a precision application.

5. Do C0G capacitors have a piezoelectric effect?

No. The piezoelectric effect in ceramic capacitors is associated with ferroelectric materials like barium titanate, which is used in Class II dielectrics. C0G uses a non-ferroelectric material and therefore does not exhibit piezoelectric behavior. This makes C0G the right choice for noise-sensitive analog circuits, audio equipment, and any application where mechanical vibration in the environment could otherwise couple into the signal path.

Summary

The C0G capacitor is the precision tool in the ceramic capacitor family. It will not win on size or capacitance density — that is not its job. Its job is to be exactly the value on the label, at the temperature on your bench, at the voltage in your circuit, and still be exactly that value ten years later. When your circuit depends on a specific capacitance — in a timing network, a crystal oscillator load, an RF matching network, a PLL filter, or a precision analog chain — the C0G capacitor is the part that keeps everything working as designed. Use it deliberately, and you will avoid a whole class of subtle, temperature-dependent bugs that are genuinely painful to trace on hardware.

For everything else, X7R is usually the right default. But knowing exactly where that line is drawn is what separates a robust design from one that needs a board respin when the operating temperature changes.