ISL3984 Intersil Corporation, ISL3984 Datasheet - Page 2

• Manufacturer Part Number: ISL3984
• Description: Power Amplifier and Detector
• Manufacturer: Intersil Corporation

Pin Descriptions
The ISL3984 works seamlessly with the PRISM II and
PRISM II.V WLAN chip set components to give you a highly
integrated, cost effective 11Mb/s WLAN solution in the 2.4 to
2.5GHz ISM band. The ISL3984 is fabricated in the fastest
SiGe BiCMOS process available allowing superior RF
performance, normally found only in GaAs ICs. Cost effective
functions, normally requiring external components, are
integrated into one IC. The ISL3984 integrates the following
functions in one compact 16 pin MLFP:
PIN NUMBER
• Two Stage, 30dB Gain RFPA,
• Logarithmic power detect function (15dB Dynamic
• CMOS level compatible Power Up/Down function,
• Single Supply, 2.7V to 3.6V Operation.
7, 8, 9, 10
Range),
4, 5
11
12
13
14
15
16
1
2
3
6
BIAS_VCC Power Supply.
BIAS_GND DC and RF Ground.
DET_OUT Detector Output.
VCC_DET Detector Power Supply.
DS_VCC
RF_OUT
NAME
RF_IN
REXT
GND
GND
GND
PE
2
Bias Resistor, biasing scheme
independent of absolute
temperature.
Driver Stage Power Supply.
DC and RF Ground.
RF Output of the Power Amplifier.
DC and RF Ground.
RF Input of the Power Amplifier.
DC and RF Ground.
Digital Input Control Pin to enable
operation of the Power Amplifier.
Enable logic level is high.
DESCRIPTION
ISL3984
The ISL3984 contains a highly linear RFPA designed to deliver
18dBm and meet an ACPR specification of -30dBc in the 2.4 to
2.5GHz ISM band. The performance of this two stage RFPA
can be optimized by adjusting the bias current with a dedicated
resistor. No external positive or negative power supplies are
required to set the bias currents. The on chip bias network
provides the optimum bias current temperature compensation
when low TC external resistor is used. To get the best
performance from the ISL3984, the output stage matching
network can be tailored using external components.
The ISL3984 power detect function provides a DC output
voltage that is proportional to the logarithm of the output
power. For an output power of 18dBm, the detector is
accurate to within a 0.5dB. The slope of the detector output
voltage is 100mV/dB over a 15dB dynamic range. A simple
application of the detector is to provide in-line monitoring of
the output power using a DC voltmeter. No longer is a power
meter or spectrum analyzer required. A more value added
application would use the HFA3861B/HFA3863 Baseband
Processor to dynamically monitor the ISL3984 output power
and to control transmit power by adjusting the AGC of the
HFA3783 IF Quadrature Modem to provide the best possible
error free data transfer rate for any given environment.
Closed loop power control is very important feature which
compensates for variability in the transmit chain (radio to
radio, channel to channel, over temperature...).
The ISL3984 power up/down feature integrates the power
down capability onto the IC and requires no external
components thus freeing up board space and reducing
external component count and cost. When the CMOS
compatible Power Enable (PE) pin is driven low, the total
supply current drops to under 50 A in, typically, 300ns.
When the PE pin is driven high, the full ISL3984 output
power is available in a few hundred nanoseconds.
In summary, the ISL3984 RFPA provides a highly cost
effective solution for the PA function by integrating many
features that would require significant development time,
drive up the total bill of materials cost and consume precious
board space. It mates seamlessly with the other PRISM II
ICs to provide a highly integrated, cost effective 11Mb/s
WLAN solution in the 2.4 to 2.5GHz ISM band.