tqm7138 TriQuint Semiconductor, tqm7138 Datasheet - Page 5

• Manufacturer Part Number: tqm7138
• Description: 3v Hbt Sige Cdma 4x4mm Power Amplifier Module
• Manufacturer: TriQuint Semiconductor

Product Description:
The TQM7138 is a two stage SiGe HBT power amplifier module in
a cascade configuration intended for use in CDMA Cellular band
handsets.
Operation
The operation modes of the TQM7138 are determined based on
the setting of V
operating mode. Also, if the TQM7138 will be used in continuous
bias mode V
ground.
Application
The applications circuit for the TQM7138 is very simple since most
of the critical components are included inside the module. There
are several important considerations when using the module in a
phone design.
First of all, it is important that the source impedance of the V
power supply be very low. This is because the high current
demand during the modulation peaks of the CDMA waveform can
introduce voltage ripple at the symbol rate that will introduce
additional inter-modulation distortion or Adjacent Channel Power
distortion at the output of the power amplifier. If the power
amplifier has a quiescent current of 100 mA and a peak current
demand in excess of 1 amp, it is possible to see 900 mA change
in the current required from V
from one extreme to the other. If the power supply source
High Power
Low-Power
Continuous
Operating
Mode
Bias
Off
CNTRL
CNTRL
must be connected on the circuit board to
and V
V
High
CNTRL1
Low
Low
Low
REF
. The truth table below defines the
CC
For additional information and latest specifications, see our website: www.triquint.com
as the modulated signal moves
>2.7VDC
>2.7VDC
3.0VDC
~1.9 to
0VDC
V
REF
CC
impedance were 1 ohm, the resulting voltage ripple would be 0.9
volts which would cause the amplifier to fail it ACP requirements.
Generally, the power supply source impedance should be kept as
low as possible, preferably below 0.1 ohms total. Most battery
technologies used in cellular telephones will support a low source
impedance, but it may be necessary to supplement this in some
designs with an low ESR capacitor. Ceramic or tantalum
capacitors of approximately 10 micro-farads work well for this
requirement.
The application circuit includes 0.1 F capacitors at each of the
PA control lines and V
Depending on the phone board layout and circuit bypassing in
other areas of the phone, some of these components may not be
necessary. There are a number of VCO signals and IF signals
used in a given phone design, so it is important to protect the PA
module from interfering signals and to limit any interference
coming from the PA itself. Care should be taken when removing
any of the RF bypassing components.
One final area of concern is with excessive bypassing. If too large
a value of bypassing capacitor is used on any of the control lines,
it could reduce the frequency response of that control line to the
point where a specification failure could occur. Please be sure
that the logic lines and regulated supply lines driving the power
amplifier control lines are adequate to supply peak current
requirements of the bypassing capacitors chosen on the control
lines.
One Bias State Operation
The TQM7138 can be operated using one bias state. If this mode
is selected, V
Continuous Bias-State Operation
The TQM7138 can be operated in continuous bias mode in which
the V
quiescent current as appropriate for the desired output power
level. In this mode, V
phone board. Specific application circuit information for this mode
is available upon request.
REF
voltage is varied from ~1.9V to 3.0V to set the PAM
CNTRL
should be connected to ground.
CNTRL
CC
lines to ensure proper RF bypassing.
Preliminary - TQM7138
Data Sheet
should be connected to ground on the
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