PAs & LNAs, mixers/converters, T/R & duplexing, filters, gain/attenuation/detection, FEM & beamforming, linearization & LO, key specs, and design hooks.
Power Amplifiers (PA)
Linear PA (Class A/AB)
Simpler, best linearity; modest efficiency—small-cell/broadband waveforms.
High-Efficiency PA (B/C/D/E/F/J)
Switching/harmonic-tuned; strict matching/filters for high PAE.
Doherty PA
Peak+main cooperation for superior back-off efficiency; 5G base stations.
Envelope Tracking / APT
Supply follows envelope; balance EVM/ACLR vs efficiency.
PA Technologies (GaN/GaAs/SiGe/CMOS)
GaN: high V & power density; GaAs: HF linearity; CMOS: integration.
PA Metrics & Protection
P1dB/Psat/PAE, ACLR/EVM, harmonics/spurs, VSWR/thermal protection.
PA Applications
Cellular RF, Wi-Fi/BT FEMs, mmWave, ISM/LoRa, radar/SATCOM uplink.
Low-Noise Amplifiers (LNA)
Narrowband Noise-Matched LNA
Minimize NF; noise match priority—GNSS/weak signals.
Wideband LNA
Broad coverage via resistive feedback; slightly higher NF.
Switched/Tunable LNA
Gain steps & tunable match—multi-standard terminals.
LNA Specs & Blocking
NF/gain/IIP3, S-params, K-stability; blocking robustness with pre-filters.
Mixers & Converters
Passive Mixers
Low conversion loss, high linearity; higher LO drive.
Active/Balanced Mixers
Conversion gain, small LO; NF vs linearity trade-offs.
I/Q Mixers
Image suppression and zero-IF capability for SDR/cellular.
Up/Down Converters (w/ IF VGA & LO)
On-chip VGA, dividers/PLL—compact microwave TRx chains.
Mixer Metrics
Conv. gain/loss, IIP3/NF, LO–RF/IF isolation, LO leakage & image.
T/R Switches & Duplexing
Antenna / T/R Switch
Low IL, high isolation & IP3; multi-antenna routing.
Duplexer / Duplexing Filter
SAW/BAW/cavity filters for FDD UL/DL isolation.
Diplexer / Triplexer
Combining/splitting multiple bands with a shared antenna.
Filtering & Selection
SAW/BAW Filters
High-Q acoustic filters for cellular and Wi-Fi bands.
Cavity/Dielectric/Waveguide
Ultra-low loss, very high Q—microwave/mmWave.
Tunable Filters & Antenna Tuners
MEMS/varactor arrays for multi-band compact devices.
Gain / Attenuation / Detection
Variable Gain Amplifiers / Digital Step Attenuators
AGC, equalization with step or voltage-controlled gain.
RF Power Detectors / Couplers
Average/peak power and VSWR sensing for PA DPD/protection.
Baluns / Ununs
Differential↔single-ended matching; wide/narrow-band options.
FEM & Beamforming
Wi-Fi/BT FEMs
PA+LNA+Switch+filters integrated; parallel MIMO chains.
Cellular FEM (Sub-6/FR1)
In-band linearity/ACLR with DPD hooks.
mmWave Beamformer / TRX
Per-channel PA/LNA with phase/amp control and TDD switching.
SATCOM/Radar Front-Ends
Low-PN LO, wide dynamic range, polarization/dual-channel.
Linearization & Local Oscillators
Digital Pre-Distortion (DPD)
Improve ACLR/EVM—requires power sensing and calibrated feedback.
Envelope Tracking
Coordinate PA supply modulation for back-off efficiency.
LO / PLL / Synthesizer
Phase-noise & spurs impact EVM/adjacent channels; see clocking.
Key Specs & Selection
Transmit Chain
Pout/PAE, ACLR/EVM, noise emission (RX decoupling), thermal & VSWR.
Receive Chain
NF/gain/dynamic range, blocking robustness, IP2/IP3, image & LO leakage.
Mixers & Converters
Conv. gain/loss, IIP3, isolation, image/2nd-harmonic suppression, LO drive.
RF Networks
S-params, Q/IL, group delay and out-of-band rejection.
System Considerations
MIMO crosstalk, antenna sharing, T/R power & linearity, thermal/ESD.
Design Hooks & Pitfalls
Noise & Cascade (Friis)
First stages dominate system NF—budget accordingly.
Linearity & Dynamic Range
Cascade IIP3; reserve headroom and insert DSA in blockers.
Matching vs Stability
Noise vs power match; K>1, |Δ|<1; add series R/ferrite as needed.
Isolation & Leakage
Orthogonal LO/RF/IF routing, shielding, avoid self-mixing paths.
Power & Biasing
Low-noise LDOs, RC filtering, ET/thermal comp, safe sequencing.
Thermal & Mechanics
PA pad copper/vias, airflow paths; FEM thermal co-coupling.
EVM/ACLR Tuning
DPD + DSA + ET; check sampling BW and feedback latency.
Compliance & Testing
Spectrum masks, harmonics/spurs, TRP/TIS per CTIA/3GPP.
