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X9470 Datasheet, PDF (1/24 Pages) Xicor Inc. – RF Power Amplifier (PA) Bias Controller
®
PRELIMINARY
Data Sheet
March 8, 2005
X9470
FN8204.0
RF Power Amplifier (PA) Bias Controller
FEATURES
• Programmable Bias Controller IC for Class A
and AB LDMOS Power Amplifiers
• Adaptive System on Chip Solution
• Bias Current Calibration to better than ±4%
using Reference Trim DCP
• Automatic Bias Point Tracking and Calibration
— IDQ Sensing and Tracking
—Programmable Instrumentation Amplifier to
Scale Wide Range of IDQ
—Programmable Gate Bias Driver
—All Programmable settings are Nonvolatile
—All Settings Recalled at Power-up.
• 28V Maximum VDD
• 2 Wire Interface for Programming Bias Setting
and Optimizing IDQ Set Point
• Bias Level Comparator
• Shutdown Control pin for PA Signal
• Slave address to allow for multiple devices
• 24-pin TSSOP Package
• Applications: Cellular Base Stations (GSM,
UMTS, CDMA, EDGE), TDD applications, Point-
to-multipoint, and other RF power transmission
systems
DESCRIPTION
The Intersil X9470 RF PA Bias Controller contains all of
the necessary analog components to sense the PA
drain current through an external sense resistor and
automatically control the gate bias voltage of an
LDMOS PA. The external sense resistor voltage is am-
plified by an instrumentation amplifier and the output of
the amplifier along with an external reference voltage is
fed to the inputs of a comparator. The comparator out-
put indicates which direction the LDMOS gate bias volt-
age will move in the next calibration cycle. System
calibration is accomplished by enabling the X9470 and
providing a clock to the SCL pin. The LDMOS drain cur-
rent can be maintained constant over temperature and
aging changes by periodic calibration. The VOUT pin
can be used to monitor the average power by tracking
the drain current. Up to eight X9470 or additional Inter-
sil Digital Potentiometers can be controlled via a two-
wire serial bus.
TYPICAL APPLICATION
INC/DEC
RWREF RHREF RLREF AGND VOUT V+
VDD
A2
RREF
A1
VREF
Comparator
A0
VP
Instrumentation
Amplifier
VSENSE+
CBULK
∆V VSENSE– RSENSE
SDA
SCL
I2C
interface
Control &
Status Registers
EEPROM
Vbias
control
VREF
control
RBIAS
+
–
choke
VBIAS
FILTER
RF
out
RF PA in
Matching
RF Impedance
VCC VSS
CS RHBIAS RWBIAS RLBIAS SHDN
Class A Example
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright Intersil Americas Inc. 2005. All Rights Reserved
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