Every RF system routes signals somewhere: between antennas, through filter banks, into test ports. The switch you choose sets your insertion loss, isolation, linearity, switching speed, and lifetime — and no single technology wins all five. Here is how the main families actually compare.
The Contenders
| Technology | Insertion Loss | Isolation | Switching Speed | Power Handling | Lifetime | Best For |
|---|---|---|---|---|---|---|
| PIN diode | 0.3–1 dB | 25–50 dB | µs – ms | Very high (W–kW) | Essentially unlimited | High-power TX paths, limiters, toggled attenuators |
| GaAs/GaN FET IC | 0.2–1 dB | 25–40 dB | ns – µs | +25 – +45 dBm typical | Unlimited (no wear) | T/R modules, phased arrays, broadband switching |
| SOI CMOS IC | 0.3–0.9 dB | 22–35 dB | ns | +20 – +35 dBm | Unlimited | Cellular/Wi-Fi front ends, low-cost multi-throw |
| Electromechanical relay | 0.05–0.2 dB | 60 – >100 dB | 1–20 ms | High (depends on contacts) | 1M–10M cycles | Test & measurement, lab automation, matrix switching |
PIN Diodes: Power First
A PIN diode is a current-controlled RF resistor: DC bias makes it conduct RF, reverse bias isolates it. Its virtues are power handling and ruggedness — it survives kilowatts when properly biased and is the default in TX switching, limb limiting, and high-power attenuators. Costs: it needs continuous bias current, its driver circuitry matters (switching speed trades against current), and distortion at low bias is real — check the diode's carrier lifetime against your lowest RF frequency.
FET ICs: Speed and Integration
GaAs, GaN, and increasingly SOI-CMOS FET switches integrate multi-throw topologies with logic-level control in tiny packages, switch in nanoseconds, and never wear out. They dominate phased arrays, T/R modules, and handset front ends. The specs to scrutinize are linearity (P1dB and IP3 at your control voltage), isolation at high frequency, and how performance degrades with control-voltage variation — the difference between a datasheet headline and your real system.
Electromechanical Relays: The Reference Standard
A mechanical contact simply cannot be beaten on raw numbers: insertion loss near zero, isolation beyond 100 dB in coaxial designs, and RF power limited only by the contacts. That is why calibration switch matrices and production test systems still use them despite millisecond switching and finite mechanical life (count your cycles honestly — a relay rated 1 million cycles fails quickly at 10 Hz around the clock). Specify contact form, coil voltage, and life at your actual RF power, not the datasheet's dry-contact number.
Choosing in Five Questions
- What RF power must the switch survive, continuously and hot? — eliminates half the field immediately.
- How fast must it switch? — ns (FET), µs (PIN), ms (relay).
- What isolation do you truly need? — 30 dB for many systems, 90 dB for metrology.
- How many cycles over the product's life? — mechanical life is a budget, not a footnote.
- What control interface does the rest of the board speak? — logic-level SPI vs. driver current.
JTDZ Tech stocks PIN diodes, GaAs/GaN and SOI RF switch ICs, and RF relays from the major manufacturers, with date codes and full traceability. Send us your switching requirements — topology, power, speed — and we will quote matching parts within two business hours.
