Tx-Rx Front-End Module for Quad-Band GSM / GPRS / EDGE w/ 10 Linear TRx Switch Ports, Dual-Band TD-SCDMA, and TDD LTE Band 39

SKY77912-21, a Tx / Rx Front-End Module (FEM), offers the complete transmit VCO-to-Antenna and Antenna-to-receive SAW filter solution for advanced cellular handsets comprising quad-band GSM, GPRS, EDGE multi-slot operation, and TD-SCDMA and TDD LTE transmission. The FEM fully enables broadband 3G/4G RF switch-through, outward switching of the Power Amplifier (PA) RF inputs, ten transmit / receive (TRx) antenna switch ports, and an integrated directional coupler.

A new multi-standard CMOS controller provides PA band/mode selection and bias control, including the Mobile Industry Processor Interface (MIPI®) RFFE logic, and switch decoder circuitry. The controller supports user-optional control of linear RF or analog VRAMP of the GMSK envelope. A distinct MIPI register mapping included in this Data Sheet provides for each of these control paradigms, including associated approaches to PA and switch control.

The Heterojunction Bipolar Transistor (HBT) PA blocks are fabricated in Gallium Arsenide (GaAs). The low band (LB) PA transmits in the GSM850/900 bands. The high band (HB) PA supports DCS, PCS, TD-SCDMA bands 34/39, and TDD LTE band 39. The HBT, switch, and controller die, and passive components mount onto a multi-layer laminate substrate and the entire assembly encapsulated with plastic over-mold.

Built into the SKY77912-21 is a complete features set for state-of-the-art performance and minimal phone board complexity, including PA over-voltage and over-current protection, 50 ohms matching and zero DC offset on all RF pins, TRx high linearity/low loss switching and high off-state isolation, integrated directional coupler, IEC ruggedness at antenna output, LB and HB input switching for alternate RF routing 3G/4G Tx paths, power supply pads shared between LB and HB, and ultra-low leakage currents for long standby times.

Selecting the linear-GMSK operation standard disables VRAMP input so all PA biasing depends only on MIPI mode selection. The transmitted envelope is a linear function of RF input.

Selecting VRAMP-enabled operation, the PA controller provides VRAMP control of the GMSK envelope and reduces sensitivity to input drive, temperature, power supply, and process variations. Skyworks’ Finger-Based Integrated Power Amplifier Control (FB-iPAC) minimizes output power variation into mismatch. In EDGE and TD-SCDMA / TDD LTE linear modes, VRAMP voltage and MIPI-based bias settings jointly optimize PA linearity and efficiency.


  • Small, low profile package: 5.5 mm x 5.3 mm x 0.8 mm Max, 38-pad configuration
  • MIPI® RFFE control with dual-standard support
    • User-selectable register mappings
    • Linear or VRAMP-based GMSK power control
  • RF ports internally matched to 50  load
  • High Efficiency (inclusive of coupler)
  • Tx harmonics below –40 dBm
  • Supports APT, buck DC-DC supply
  • Ten low insertion loss/high linearity TRx switch ports
  • RF input switching to 3G/4G path
  • Integrated broadband directional coupler
  • Integrated noise suppression notch filter for WiFi coexistence
  • Built-in IEC-compliant antenna ESD protection
  • High impedance control inputs: 20 μA, maximum
  • Current limiting and over-voltage protection for ruggedness and extended battery life
  • Power control circuitry built-in for improved TRP variation
Product Summary SKY77912-21 Tx-Rx Front-End Module for Quad-Band GSM / GPRS / EDGE w/ 10 Linear TRx Switch Ports, Dual-Band TD-SCDMA, and TDD LTE Band 39 SKY77912_21_203476A.pdf (84 KB)
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Description : Tx-Rx Front-End Module for Quad-Band GSM / GPRS / EDGE w/ 10 Linear TRx Switch Ports, Dual-Band TD-SCDMA, and TDD LTE Band 39
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