LTC1957-2EMS#TR Linear Technology, LTC1957-2EMS#TR Datasheet - Page 11

• Manufacturer Part Number: LTC1957-2EMS#TR
• Description: IC RF PWR CONTROLLR DUAL 10-MSOP
• Manufacturer: Linear Technology

Specifications of LTC1957-2EMS#TR

• Rf Type: Cellular, GSM, GPRS, PCS, Wireless Modem, TDMA
• Frequency: 850MHz ~ 2GHz
• Features: Dual Output
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (max): 6V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 10
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC1957-2EMSTR

External pole frequencies within the loop will further
reduce phase margin. The phase margin degradation, due
to external and internal pole combinations, is difficult to
determine since complex poles are present. Gain peaking
may occur, resulting in higher bandwidth and lower phase
margin than predicted from the open loop Bode plot. A low
frequency AC SPICE model of the LTC1957 power control-
ler is included to better determine pole and zero interac-
tions. The user can apply external gains and poles to
determine bandwidth and phase margin. DC, transient and
RF information cannot be extracted from the present
model. The model is suitable for external gain evaluations
up to 6 . The 350kHz PCTL input filter limits the band-
width, therefore, use the RF input as demonstrated in the
model.
This model (Figure 7) is being supplied to LTC users as an
aid to circuit designs. While the model reflects reasonably
close similarity to corresponding devices in low frequency
AC performance terms, its use is not suggested as a
replacement for breadboarding. Simulation should be
used as a forerunner or a supplement to traditional lab
testing.
Users should note very carefully the following factors
regarding this model: Model performance in general will
reflect typical baseline specs for a given device, and
certain aspects of performance may not be modeled fully.
While reasonable care has been taken in the preparation,
we cannot be responsible for correct application on any
and all computer systems. Model users are hereby notified
that these models are supplied “as is”, with no direct or
implied responsibility on the part of LTC for their operation
APPLICATIO S I FOR ATIO
PCTL
+
Figure 5. Closed Loop Block Diagram
I
FB
–
BW1 370kHz
RF DETECTOR
AMPLIFER
CONTROL
LTC1957
U
G1
H1
U
V
RF
PCA/B
14dB to 20dB LOSS
RF POWER AMP
DIRECTIONAL
COUPLER
G2
H2
W
1957 F05
CONTROLLED
RF OUTPUT
POWER
U
within a customer circuit or system. Further, Linear Tech-
nology Corporation reserves the right to change these
models without prior notice.
In all cases, the current data sheet information is your final
design guideline, and is the only performance guarantee.
For further technical information, refer to individual device
data sheets. Your feedback and suggestions on this model
is appreciated.
Linear Technology Corporation hereby grants the users of
this model a nonexclusive, nontransferable license to use
this model under the following conditions:
The user agrees that this model is licensed from Linear
Technology and agrees that the model may be used,
loaned, given away or included in other model libraries as
long as this notice and the model in its entirety and
unchanged is included. No right to make derivative works
or modifications to the model is granted hereby. All such
rights are reserved.
This model is provided as is. Linear Technology makes no
warranty, either expressed or implied about the suitability
or fitness of this model for any particular purpose. In no
event will Linear Technology be liable for special, collat-
eral, incidental or consequential damages in connection
with or arising out of the use of this model. It should be
remembered that models are a simplification of the actual
circuit.
Figure 6. SPICE Model Open Loop Gain and Phase
Characteristics from RF to V
–20
–40
–50
–60
–10
–30
80
70
60
50
40
30
20
10
0
100
LTC1957-1/LTC1957-2
1k
FREQUENCY (Hz)
GAIN
10k
PCA
PHASE
100k
, PCTL < 640mV
R
C
LOAD
LOAD
1M
= 33pF
= 2k
1957 F06
10M
180
160
140
120
100
80
60
40
20
0
–20
–40
–60
–80
–100
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