LT5515_15 Datasheet, PDF (1/12 Pages) Linear Technology – 1.5GHz to 2.5GHz Direct Conversion Quadrature Demodulator

FEATURES
■ _{Frequency Range: 1.5GHz to 2.5GHz}
■ _{High IIP3: 20dBm at 1.9GHz}
■ _{High IIP2: 51dBm at 1.9GHz}
■ _{Noise Figure: 16.8dB at 1.9GHz}
■ _{Conversion Gain: –0.7dB at 1.9GHz}
■ _{I/Q Gain Mismatch: 0.3dB}
■ _{I/Q Phase Mismatch: 1°}
■ _{Shutdown Mode}
■ _{16-Lead QFN 4mm × 4mm Package}
with Exposed Pad
U
APPLICATIO S
■ _{Cellular/PCS/UMTS Infrastructure}
■ _{High Linearity Direct Conversion I/Q Receiver}
■ _{High Linearity I/Q Demodulator}
■ _{RF Power Amplifier Linearization}
TYPICAL APPLICATIO
LT5515
1.5GHz to 2.5GHz
Direct Conversion
Quadrature Demodulator
DESCRIPTIO
The LT^®5515 is a 1.5GHz to 2.5GHz direct conversion
quadrature demodulator optimized for high linearity re-
ceiver applications. It is suitable for communications
receivers where an RF signal is directly converted into I
and Q baseband signals with bandwidth up to 260MHz.
The LT5515 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 LT5515 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.
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
BPF
BPF
RF⁺
LNA
RF ^–
LO⁺
LO INPUT
LO^–
ENABLE
EN
5V
V_CC
0°/90°
LT5515
I_OUT+
LPF
VGA
I_OUT–
0°
DSP
Q_OUT+
LPF
VGA
Q_OUT–
90°
5515 F01
Figure 1. High Signal-Level I/Q Demodulator for Wireless Infrastructure
I/Q Output Power, IM2, IM3
vs RF Input Power
20
0
P_OUT
– 20
IM3
– 40
IM2
– 60
– 80
–100
–16
T_A = 25°C
P_LO = –5dBm
f_LO = 1901MHz
f_RF1 = 1899.9MHz
f_RF2 = 1900.1MHz
–12 – 8 – 4 0
48
RF INPUT POWER (dBm)
5515 • TA01
5515fa
1