activeTier A
HEMT Amplifier
First cryogenic amplification of weak readout signals returning from the qubit/resonator.
What it does
High-electron-mobility transistor low-noise amplifier used as the first active gain stage in the readout output chain. This reference model is a compact 4 K coaxial cryogenic LNA package with SMA RF ports and a Nano-D style DC connector.
Where it goes
- Allowed stages
- 4K
- Preferred stages
- 4K
- Forbidden stages
- 300K, 50K, MXC
- Typical line types
- readoutOut
- Error if placed on MXC — dissipation too high for base temperature.
- Must be downstream of a circulator or isolator.
- DC bias line required; route separately on DC twisted pair.
Typical specifications
| Gain | 35 – 42 dB |
| Noise temperature | ~2 – 5 K |
| Frequency range | 4 – 8 GHz |
| Bias voltage | ~0.7 V |
| Power dissipation | 0.3 – 10.5 mW |
Ports
- RF IninreadoutOut50 Ω
- RF OutoutreadoutOut50 Ω
- DC Biasinternaldc
Physical envelope
39.2 × 20.0 × 7.8 mm
Compact cryogenic LNA envelope based on LNF-style 4–8 GHz HEMT packages: body about 25.66 × 20.0 × 7.8 mm excluding connectors, with total RF span rendered at about 39.2 mm.