LT5516
800MHz to 1.5GHz Direct
Conversion Quadrature Demodulator
FEATURES
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DESCRIPTIO
Frequency Range: 800MHz to 1.5GHz
High IIP3: 21.5dBm at 900MHz
High IIP2: 52dBm
Noise Figure: 12.8dB at 900MHz
Conversion Gain: 4.3dB at 900MHz
I/Q Gain Mismatch: 0.2dB
Shutdown Mode
16-Lead QFN 4mm
脳
4mm Package
with Exposed Pad
The LT
廬
5516 is an 800MHz to 1.5GHz direct conversion
quadrature demodulator optimized for high linearity re-
ceiver applications. It is suitable for communications
receivers where an RF or IF signal is directly converted into
I and Q baseband signals with bandwidth up to 260MHz.
The LT5516 incorporates balanced I and Q mixers, LO
buffer amplifiers and a precision, high frequency quadra-
ture generator.
In an RF receiver, the high linearity of the LT5516 provides
excellent spur-free dynamic range, even with fixed gain
front end amplification. This direct conversion receiver
can eliminate the need for intermediate frequency (IF)
signal processing, as well as the corresponding require-
ments for image filtering and IF filtering. Channel filtering
can be performed directly at the outputs of the I and Q
channels. These outputs can interface directly to channel-
select filters (LPFs) or to a baseband amplifier.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Cellular/PCS/UMTS Infrastructure
High Linearity Direct Conversion I/Q Receiver
High Linearity I/Q Demodulator
TYPICAL APPLICATIO
BPF
LNA
BPF
5V
RF
+
V
CC
LT5516
I
OUT
+
LPF
VGA
0
P
OUT
, IM3 (dBm/TONE)
RF
鈥?/div>
+
0擄
I
OUT鈥?/div>
DSP
LO INPUT
LO
Q
OUT+
0擄/90擄
LO
鈥?/div>
ENABLE
EN
90擄
Q
OUT鈥?/div>
LPF
VGA
5516 F01
Figure 1. High Signal-Level I/Q Demodulator for Wireless Infrastructure
U
I/Q Output Power, IM3 vs
RF Input Power
20
P
OUT
鈥?0
鈥?0
IM3
鈥?0
鈥?0
鈥?00
鈥?8
V
CC
= 5v
T
A
= 25擄C
P
LO
= 鈥?0dBm
f
LO
= 901MHz
f
RF1
= 899.9MHz
f
RF2
= 900.1MHz
2
6
5516 TA01
U
U
鈥?4
鈥?0
鈥?
鈥?
RF INPUT POWER (dBm)
5516f
1
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