RF Amplifiers
Function: Amplify radio frequency signals while maintaining signal integrity, gain, bandwidth, and linearity.
Key Parameters
- Gain: Output power vs. input power (dB)
- Noise Figure (NF): Signal-to-noise degradation (lower is better)
- IP3 (Third-Order Intercept): Linearity & distortion performance
- Bandwidth: Frequency range of operation
- P1dB (Compression Point): Output power at 1 dB compression
- VSWR / Return Loss: Impedance matching (typically 50Ω)
Types
| Type | Use Case | Characteristics |
|---|
| LNA | Receiver front-end | Low NF, moderate gain |
| PA | Transmitter output | High Pout, efficiency critical |
| Driver Amp | Intermediate stage | Balanced gain & linearity |
| VGA | Variable gain control | Adjustable gain via analog/digital |
Common Technologies
Bipolar (Si, SiGe), GaAs, GaN, CMOS — chosen based on frequency, power, and efficiency needs.
Design Tips
- Impedance match I/O (use Smith Chart)
- Stability check (K-factor, μ-factor)
- Proper biasing (voltage/current regulation)
- Thermal management (especially for PAs)
- Decoupling & layout (minimize parasitics)