ATC RF Capacitors Selection Guide: Which Series for Your Design?
If you design RF power amplifiers, optical modules, MRI coils, or millimeter-wave circuits, you've almost certainly encountered ATC capacitors. Now part of Kyocera-AVX, ATC remains the gold standard in high-frequency ceramic capacitors — but with 11 distinct series spanning 0.05pF to 10μF and DC to 50GHz+, choosing the right one isn't always obvious.
This guide maps each ATC capacitor series to its ideal application, with key specs, trade-offs, and real-world deployment examples. Whether you're matching a GaN PA, decoupling a 400G optical DSP, or building an MRI coil with Q>2000, there's an ATC part for it.
ATC RF Capacitor Series at a Glance
| Series | Type | Capacitance | Max Freq | Key Strength | Best For |
|---|---|---|---|---|---|
| 600S / 600L | Ultra-Low ESR NPO | 0.1–1000pF | 6GHz | ★ Q>2000, ESR<0.01ω<> | RF PA matching, MRI coils, base station |
| Accu-P® | Thin-Film | 0.05–100pF | 40GHz | ★ ±0.01pF tolerance | GaAs/GaN PA, mmWave, photonics |
| 550 / 560 UBC | Ultra-Broadband | 100pF–10μF | 50GHz+ | ★ Zero series resonance dip | 400G/800G optical modules, SerDes |
| 700 Series | High-Power Porcelain | 0.1–5100pF | 4.2GHz | 500–3,600V rated | Broadcast, radar, industrial RF |
| SLC | Single-Layer | 0.1–10000pF | 50GHz+ | Bare-die, pH parasitics | MMIC matching, hybrid circuits, mmWave |
| 100 Series | Porcelain MLCC | 0.1–1000pF | 4.2GHz | High stability, wide temp range | General RF, oscillators, filters |
| 200 Series | BX Ceramic MLCC | 0.5pF–0.82μF | 1GHz | Medium-high CV, stable TC | Power supply decoupling, bypass |
| 800 Series | NPO High-Power | 1–1000pF | 1GHz | High RF power, low loss | Transmitters, industrial RF power |
| 900 Series | X7R RF Power | 100pF–10μF | 500MHz | X7R, bulk CV for bypass | DC decoupling, bias networks |
| CU Series | Low ESL | 0.01–1μF | 10GHz | Wide-terminal, ultra-low ESL | FPGA/CPU decoupling, high-speed digital |
| KAQ Series | Automotive Grade | 0.1pF–100nF | 4GHz | AEC-Q200 qualified | 77GHz radar, V2X, in-vehicle RF |
Deep Dive: Three Flagship Series Every RF Engineer Should Know
600S / 600L — The Ultra-Low ESR Workhorse
The 600 series is ATC's most popular RF capacitor line, and for good reason. With Q factor exceeding 2,000 at 1GHz and ESR below 0.01Ω, these NPO-dielectric MLCCs deliver the lowest insertion loss in their class. They're the default choice for RF power amplifier impedance matching, where every 0.1dB of loss translates directly to heat and reduced efficiency.
In MRI receiver coils, the 600S's high Q directly improves signal-to-noise ratio (SNR). At 64MHz and 128MHz (1.5T and 3T scanners), the series achieves Q factors that competing MLCCs simply cannot match. Medical device manufacturers standardize on the 600S for exactly this reason.
Available in 0505, 0805, 100B, and 100E packages. The 600L variant offers the same electrical performance in a low-profile configuration for height-constrained designs.
Accu-P® — When a Femtometer Matters
If your matching network requires ±0.01pF tolerance, there's only one option: Accu-P thin-film capacitors. Built with thin-film electrode technology on a ceramic substrate, Accu-P offers precision that conventional MLCCs physically cannot achieve.
This precision is critical in GaAs and GaN power amplifier matching at frequencies above 10GHz, where a 0.05pF deviation can shift the impedance match by several ohms — pushing the PA outside its efficiency sweet spot. In millimeter-wave oscillators and photonics bias networks, the Accu-P's 40GHz operating range and Q>1000 at 10GHz make it irreplaceable.
Available from 0201 (0.6×0.3mm) for ultra-compact front-ends up to 0805 for applications needing higher power handling. The 0201 is the smallest RF thin-film capacitor in the industry.
UBC 550/560 — Taming the 50GHz Beast
Standard MLCCs have a fundamental problem above 10GHz: series resonance. Every capacitor has a self-resonant frequency (SRF) determined by its capacitance and parasitic inductance. Above SRF, the capacitor becomes inductive — creating a sharp insertion-loss dip that destroys broadband performance.
The Ultra-Broadband Capacitor (UBC) 550/560 series solves this with a patented internal electrode structure that suppresses the series resonance entirely. The result: flat insertion loss from below 100MHz to above 50GHz. For 100G, 400G, and 800G optical modules, where DC bias must reach the TIA or laser driver through a capacitor that can't create a resonance null in the signal band, the UBC is the only game in town.
The 550 targets lower frequencies with higher capacitance (up to 10μF), while the 560 optimizes for millimeter-wave with lower capacitance. Both suppress the resonance artifact, but the 560 provides lower insertion loss above 30GHz.
Application-by-Application Selection Guide
| Application | Recommended Series | Why |
|---|---|---|
| RF Power Amplifier Matching | 600S, Accu-P, 100 | Lowest ESR + precision for GaN/GaAs |
| Base Station / Small Cell PA | 600L, 700 | High Q + high power handling |
| Optical Module Bias (100G–800G) | UBC 550/560, SLC, CU | 50GHz+ flat response, no resonance |
| MRI Receiver Coils | 600S | Q>2000 at 64–300MHz for SNR |
| GaN MMIC Matching | Accu-P, SLC | ±0.01pF + low parasitics |
| Automotive 77GHz Radar | KAQ, Accu-P | AEC-Q200 + 40GHz operation |
| FPGA Core Decoupling | CU Series | Wide-terminal, ultra-low ESL |
| Broadcast Transmitter | 700, 800 | kV-rated, high RF current |
| Satellite / Space | 700, 600, KAQ | High-reliability porcelain |
| General RF / Prototyping | 100, KGQ | Broad availability, good Q, cost-effective |
Beyond the Capacitor: The Complete RF Passive Chain
A capacitor alone doesn't make a circuit. The RF passive chain typically requires capacitors + inductors + filters + resistors working together:
ATC RF Inductors — Thin-film & wirewound, 0.5nH–1000nH, up to 40GHz+. Essential for bias tees, matching networks, and RF chokes.
ATC LTCC Filters & Couplers — LPF, BPF, diplexers, and 3dB directional couplers from 700MHz to 6GHz. Compact LTCC construction.
ATC Thin-Film Resistors & Terminations — DC to 20GHz, 1Ω–1kΩ. For matching terminations, attenuator pads, and power dividers.
ATC SMD Antennas — Ceramic chip antennas covering 400MHz–6GHz for IoT, WiFi, BLE, GPS, and LoRa.
At Superb Automation, we stock the full ATC / Kyocera-AVX RF passive portfolio and can supply complete BOM kits — capacitors, inductors, filters, and resistors in one order. Combined with our PCB manufacturing (up to 128 layers) and PCBA assembly services, we're a single source for your RF hardware.
