rf semiconductor

**RF Semiconductors** — integrated circuits designed to process radio frequency signals (kHz to THz), enabling wireless communication, radar, and sensing applications. **Frequency Bands** - **Sub-6 GHz**: Traditional cellular (4G/5G), WiFi, Bluetooth - **mmWave (24–100 GHz)**: 5G high-band, automotive radar (77 GHz), satellite - **Sub-THz (100–300 GHz)**: 6G research, imaging **Key RF Components (on chip)** - **LNA (Low Noise Amplifier)**: First stage — amplifies weak received signal with minimal added noise - **PA (Power Amplifier)**: Final stage — amplifies signal for transmission. Highest power consumer - **Mixer**: Frequency conversion (upconvert for TX, downconvert for RX) - **PLL/Synthesizer**: Generate precise local oscillator frequency - **Filter**: Select desired band, reject interference - **ADC/DAC**: Convert between analog RF and digital baseband **Technology Choices** - **CMOS**: Lowest cost, highest integration. Dominant for WiFi, Bluetooth, some 5G - **SiGe BiCMOS**: Better noise and linearity. Used for mmWave 5G, radar - **GaAs**: Highest PA efficiency. Used in phone RF front-ends - **GaN**: Highest power. Used for base stations, military radar, satellite - **InP**: Highest frequency. Used for 100+ GHz, optical communication **RF design** requires simultaneous optimization of noise, linearity, power, and frequency — it's among the most challenging areas of IC design.