LT5554IUH#TRPBF Linear Technology, LT5554IUH#TRPBF Datasheet - Page 17

• Manufacturer Part Number: LT5554IUH#TRPBF
• Description: IC VGA DIG CONTROL 32-QFN
• Manufacturer: Linear Technology

Specifications of LT5554IUH#TRPBF

• Applications: Variable Gain (VGA)
• Number Of Circuits: 1
• -3db Bandwidth: 1GHz
• Current - Supply: 200mA
• Voltage - Supply, Single/dual (±): 4.75 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 32-WFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DEFINITION OF SPECIFICATIONS
Noise Defi nitions for 50Ω Matched Input
e
e
i
v
RTI
V
APPLICATIONS INFORMATION
Circuit Operation
The LT5554 is a high dynamic range programmable-gain
amplifi er. It consists of the following sections:
• An input variable attenuator with 50Ω input imped-
• A differential programmable transconductance ampli-
• Programmable logic blocks
• Internal bias (voltage regulators)
• Enable/disable circuit
• Overdrive protection circuit
N
RS
N
N
ONOISE
ance (four 4dB steps, controlled by PG5, PG6 inputs)
fi er (32 steps, 0.125dB each controlled by PG0, PG1,
PG2, PG3, PG4 inputs)
Source resistor RMS noise voltage:
Equivalent short-circuit input RMS noise voltage
source
Equivalent open-circuit input RMS noise current
source
Equivalent total input RMS noise voltage
source:
v
Referred-to-input LT5554 noise voltage:
RTI =
e
e
V
LT5554 output noise voltage:
N
RS
RS
ONOISE
2
2
= e
=
=
0 9
N
4
.
2
(e
=
• • •
Hz
+ i
nV
k T R
RS
N
2
⎛
⎜
⎜
⎝
2
+ e + i
RTI +
• R
N
2
S
S
2
2
2
;
for R
(R
⎛
⎝ ⎜
N
S
2
e
RS
2
= 50Ω)
• R )
S
⎞
⎠ ⎟
=
S
2
50
2
⎞
⎟
⎟
⎠
Ω
• 10
=
,
v
2
⎛
⎝ ⎜
N
GV
2 2 0
⎞
⎠ ⎟
NF
Linearity Defi nitions for 50Ω Matched Input
IMD3[dBc]
IIP3[dBm]
SFDR[dBm/Hz]
OIP3[dBm]
Since no internal feedback network is used between ampli-
fi er outputs and inputs, the LT5554 is able to offer:
• Unconditional stability for I/O reactive loading such
• High reverse isolation
The LT5554 is a class-A transconductance amplifi er. An
input signal voltage is fi rst converted to an output cur-
rent via the LT5554 internal G
(R
R
the SFDR performance is almost independent of R
values of 25Ω to 100Ω.
OUT
OUT
as fi lters (no isolation output resistors required)
sets the LT5554 gain and output noise fl oor. However,
) converts the output current into an output voltage.
Noise fi gure in dB according to any of the fol-
lowing equations:
NF
10
log
=
10
⎛
⎜
⎝
1
Third-order intermodulation product
(negative value)
log
IIP3 = P (per-tone) –
SFDR =
OIP
e
+
RS
V V
⎛
⎜
⎜
⎝
3
N
1
2
=
2
+
⎞
⎟ =
⎠
P
(
IN
OUT
⎛
⎝ ⎜
e
N
2
3
10
M
2
⎞
⎠ ⎟
. And then, the output load
–
+
log
• 174 + IIP3 – NF
e
IMD
i
RS
N
(
2
2
⎛
⎜
⎜
⎜
⎜
⎝
2
•
⎛
⎝ ⎜
1
3
R
+
e
=
S
RS
2
RTI
2
IIP
)
IMD3
⎞
⎠ ⎟
⎞
⎟
⎟
⎠
LT5554
2
3
2
2
=
+
⎞ ⎞
⎟
⎟
⎟
⎟
⎠
G
P
17
OUT
)
5554f
for