News from: Xicor
Edited by: Electronicstalk Editorial Team on 7 March 2003
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Xicor has a new RF power amplifier bias controller that integrates onto a single chip all the critical functional elements needed to provide system designers with an easily implemented solution for optimising LDMOS power amplifier performance.
Xicor's X9470 is the industry's first fully integrated single-chip solution designed specifically to provide the designer with full flexibility for monitoring and optimising the operating bias of RF power amplifiers in CDMA, WCDMA, GSM, Edge, UMTS or other similar basestation applications.
The X9470 will work with 2G, 2.5G and 3G systems as well as point to multipoint and wireless local loop systems.
During a closed-loop calibration operation, performed between RF bursts, the device's instrumentation amplifier senses the power amplifier bias current and compares this with the desired value stored in EEPROM.
A corrected bias voltage is then applied to the LDMOS power amplifier through the output amplifier that has low output resistance and thus allows a simplification of the external lowpass filter.
LDMOS bias current can be typically maintained to within 4% of its desired value over time and temperature thereby improving the power amplifier performance.
Consequently this reduces the complexity of the power amplifier design.
The flexibility of the X9470 architecture also enables open-loop calibration, reducing test time and eliminating manual calibration procedures.
Operating from a maximum supply of 30V, the X9470 features a two-wire interface for programming bias settings and optimising IDQ set point, and bias error direction flag.
A slave address feature allows control of multiple LDMOS devices in a single amplifier.
The X9470's bias circuit design and parametric analysis is simplified by Xicor's X9470 development and evaluation tool.
The device's automatic bias point tracking and calibration provides a number of features; drain current (IDQ) monitoring and tracking, programmable bias driver with ultra-stable output buffer, programmable instrumentation amplifier to scale wide a range of IDQ.
All programmable settings are nonvolatile, and an instrument amplifier output is available for diagnostics.
Production quantities for the X9470 are available in 24-lead TSSOP packaging.
