Modular support
31 March 2009
FEM with power control for quad band handsets.
A suite of Front-End Modules (FEM) with power control performance for quad band cellular handsets was introduced by Skyworks. The power control scheme is based on a coupler detector which enhances the Total Radiated Power (TRP) performance. These small footprint GSM, GPRS and EDGE solutions support Broadcom’s, Infineon’s and MediaTek’s 2.5G and 3G platforms.
“Skyworks’ highly integrated front-end modules utilise a small footprint and unique power control scheme to improve total radiated power performance – a key factor in today’s advanced handsets,” said Thomas Richter, Skyworks’ director of product marketing for front-end solutions. “Our complete transmission to antenna solution with integrated electrostatic discharge network is the perfect combination for today’s mobile handset manufacturers as they look to reduce bill-of-materials and printed circuit board footprint.”
The SKY77527 (8 x 6 x 1.12 mm) – optimised for Infineon’s reference designs – and the SKY77528 (8 x 6 x 1.1 mm) – supporting Broadcom’s platform – consist of a GSM850/900 and DCS1800/PCS1900 PA block, impedance matching circuitry for 50 Ω input and output impedances, a multifunction PA control (MFC) block, low pass harmonic rejection filters, and a single pole six throw (SP6T) antenna transmit/receive (T/R) switch. The MFC in the SKY77527 provides “pinout” for interoperation with an external power control loop. The external circuit uses the linear detector output to provide closed loop power control in EDGE and Gaussian Minimum Shift Keying (GMSK) modes of operation.
With an integrated saturation, detection and correction circuit, the SKY77528 also improves phone reliability with Output Radio Frequency Spectrum (ORFS) performance in Voltage Standing Wave Radio (VSWR) and low-battery condition.
The SKY77529 (7.5 x 7 x 1.1 mm) – also optimised for Infineon’s reference designs – consists of a GSM850/900 PA block and a DCS1800/PCS1900 PA block, a printed directional coupler for each block impedance-matching circuitry for 50 Ω input and output impedances, a MFC block, low pass harmonic rejection filters, and a SP8T antenna T/R switch. The FEM, with an antenna that connects to any one of two reception (Rx) or four Wideband Code Division Multiple Access (WCDMA) Rx/Tx ports, incorporates full support for a serial peripheral interface (SPI) bus function.
The SPI controller, which offers convenient digital control, accepts SPI telegrams with data fields that support PA and switchplexer-related functions. All FEM operating modes and switch states shall be determined by the SPI telegram. The MFC provides pinout for interoperation with a specified transceiver that will establish a closed loop power control mechanism. The external circuit uses the linear detector output to set a fixed bias point for 8PSK (EDGE) mode and a variable bias point for GMSK (GSM) mode, which allows easy-to-implement timing and calibration.
Finally, the SKY77546 (7 x 6 x 1.0 mm) consists of an Extended Global System for Mobile communications (EGSM900) PA block and a DCS1800 PA block, impedance-matching circuitry for 50 Ω inputs and outputs, a multi-function PA control block, low pass harmonic rejection filter, and a Tx/Rx antenna switch. Supporting MediaTek’s low-cost EDGE platform, the module contains a diplexer filter that provides excellent harmonics and electrostatic discharge (ESD) performance.
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