LT5557_11 Datasheet, PDF (1/18 Pages) –

LT5557
400MHz to 3.8GHz 3.3V
Active Downconverting Mixer
Features
n _{Wide RF Frequency Range: 400MHz to 3.8GHz*}
n _{High Input IP3: 25.6dBm at 900MHz}
24.7dBm at 1950MHz
23.7dBm at 2.6GHz
n _{Conversion Gain: 3.3dB at 900MHz}
2.9dB at 1950MHz
n _{–3dBm LO Drive Level}
n _{Low LO Leakage}
n _{Low Noise Figure: 10.6dB at 900MHz}
11.7dB at 1950MHz
n _{Low Power: 3.3V/269mW}
n _{50Ω Single-Ended RF and LO Ports}
n _{Very Few External Components}
n _{16-Lead (4mm × 4mm) QFN Package}
Applications
n _{Cellular, CDMA, WCDMA, TD-SCDMA and UMTS}
Infrastructure
n _WiMAX
n _{Wireless Infrastructure Receiver}
n _{Wireless Infrastructure PA Linearization}
n _{900MHz/2.4GHz/3.5GHz WLAN}
Description
The LT^®5557 active mixer is optimized for high linearity,
wide dynamic range downconverter applications. The
IC includes a high speed differential LO buffer amplifier
driving a double-balanced mixer. Broadband, integrated
transformers on the RF and LO inputs provide single-ended
50Ω interfaces. The differential IF output allows convenient
interfacing to differential IF filters and amplifiers, or is
easily matched to drive a single-ended 50Ω load, with or
without an external transformer.
The RF input is internally matched to 50Ω from 1.6GHz
to 2.3GHz, and the LO input is internally matched to 50Ω
from 1GHz to 5GHz. The frequency range of both ports
is easily extended with simple external matching. The IF
output is partially matched and usable for IF frequencies
up to 600MHz.
The LT5557’s high level of integration minimizes the total
solution cost, board space and system-level variation.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective
owners.\*Operation over a wider frequency range is possible with reduced performance.
Consult factory for information and assistance.
Typical Application
High Signal Level Downmixer for Multi-Carrier Wireless Infrastructure
LO INPUT
–3dBm (TYP)
LT5557
RF
INPUT
RF
BIAS
GND EN ^VCC2 ^VCC1
1nF
4.7pF
IF⁺
100nH
1nF
150nH
4.7pF
IF^–
100nH
3.3V
1µF
5557 TA01a
IF
OUTPUT
240MHz
Conversion Gain, IIP3, SSB NF and
LO Leakage vs RF Frequency
26
24
22
20
18
16
14
12
10
8
6
4
2
1700
IIP3
SSB NF
0
10
LOW SIDE LO
IF = 240MHz
P_LO = –3dBm
20
TA = 25°C
V_CC = 3.3V
30
40
LO-IF
LO-RF
50
G_C
1800 1900 2000 2100
RF FREQUENCY (MHz)
60
2200
5557 TA01b
5557fc
1