LT5517_15 Datasheet, PDF (1/12 Pages) Linear Technology – 40MHz to 900MHz Quadrature Demodulator

FEATURES
s _{RF Input Frequency Range: 40MHz to 900MHz}
s _{High IIP3: 21dBm at 800MHz}
s _{High IIP2: 58dBm at 800MHz}
s _{I/Q Gain Mismatch: 0.3dB Max}
s _{I/Q Phase Mismatch: 0.7°}
s _{Noise Figure: 12.4dB at 800MHz}
s _{Conversion Gain: 3.3dB at 800MHz}
s _{Baseband Bandwidth: 130MHz}
s _{Single Ended, 50Ω Matched 2XLO Input}
s _{Shutdown Mode}
s _{16-Lead QFN (4mm × 4mm) Package}
with Exposed Pad
U
APPLICATIO S
s _{Wireless Infrastructure}
s _{High Linearity Direct Conversion I/Q Receiver}
s _{High Linearity I/Q Demodulator}
LT5517
40MHz to 900MHz
Quadrature Demodulator
DESCRIPTIO
The LT^®5517 is a 40MHz to 900MHz quadrature demodu-
lator optimized for high linearity receiver applications
where high dynamic range is important. It is suitable for
communications receivers where an RF or IF signal is
directly converted into I and Q baseband signals with a
bandwidth up to 130MHz. The LT5517 incorporates bal-
anced I and Q mixers, LO buffer amplifiers and a precision,
broadband quadrature generator derived from an on-chip
divide-by-two circuit.
The superior linearity and low noise performance of the
LT5517 is achieved across its full frequency range. A well-
balanced divide-by-two circuit generates precision quadra-
ture LO carriers to drive the I mixer and the Q mixer.
Consequently, the outputs of the I-channel and the
Q-channel are well matched in amplitude, and their phases
are 90° apart. The LT5517 also provides excellent 50Ω
impedance matching at the 2XLO port across its entire
frequency range.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
BPF
BPF
RF⁺
LNA
RF ^–
5V
V_CC
LT5517
I_OUT+ ^LPF
VGA
I_OUT–
0°
DSP
2xLO
INPUT
2xLO
÷2
ENABLE
EN
Q_OUT+ ^LPF
VGA
Q_OUT–
90°
5517 F01
Figure 1. High Signal-Level I/Q Demodulator for 450MHz Infrastructure Receiver
I/Q Output Power, IM3, IM2
vs RF Input Power
20
0
–20 _{TA = 25°C}
P_2XLO = –10dBm
–40 f2XLO = 1602MHz
f_RF1 = 799.9MHz
f_RF2 = 800.1MHz
–60
P_OUT
IM3
IM2
–80
–100
–18
–14 –10 –6
–2
2
RF INPUT POWER (dBm)
5517 F01b
5517f
1