LT5517EUF Linear Technology, LT5517EUF Datasheet - Page 10

• Manufacturer Part Number: LT5517EUF
• Description: IC DEMOD QUAD 40-900MHZ 16-QFN
• Manufacturer: Linear Technology

Specifications of LT5517EUF

• Function: Demodulator
• Lo Frequency: 80MHz ~ 1.8GHz
• Rf Frequency: 40MHz ~ 900MHz
• P1db: 10dBm
• Gain: 3.3dB
• Noise Figure: 12.4dB
• Current - Supply: 110mA
• Voltage - Supply: 4.5 V ~ 5.25 V
• Package / Case: 16-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
approach is to terminate each output with a shunt capaci-
tor. The capacitor value can be optimized depending upon
the operating frequency and the specific PCB layout.
The phase relationship between the I-channel output sig-
nal and the Q-channel output signal is fixed. When the LO
input frequency is higher than the RF input frequency, then
the Q-channel outputs (Q
outputs (I
When the LO input frequency is lower than the RF input
frequency, then the Q-channel outputs lag the I-channel
outputs by 90 . Note that the phase relationship of the I-
and Q-channel outputs relative to the LO can vary by 180 ,
depending on start-up conditions. This is the nature of a
frequency divider-based quadrature phase generator.
LT5517
10
OUT
+
, I
OUT
U
–
) by 90 .
U
OUT
+
, Q
OUT
V
W
CC
–
) lead the I-channel
60
10pF
Figure 7. I/Q Output Equivalent Circuit
60
U
60
10pF
60
When AC output coupling is used, the resulting highpass
filter’s –3dB roll-off frequency is defined by the R-C
constant of the blocking capacitor and R
R
Care should be taken when the demodulator’s outputs are
DC coupled to the external load to make sure that the I/Q
mixers are biased properly. If the current drain from the
outputs exceeds 6mA, there can be significant degrada-
tion of the linearity performance. Each output can sink no
more than 13mA when connected to an external load with
a DC voltage higher than V
LOAD
> 600 .
Q
Q
I
I
OUT
OUT
OUT
OUT
5517 F07
+
–
+
–
16
15
14
13
CC
– 0.78V.
LOAD
, assuming
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