LTC5585_15 Datasheet, PDF (1/38 Pages) Linear Technology – Wideband IQ Demodulator with IIP2 and DC Offset Control

LTC5585
FEATURES
Wideband IQ Demodulator
with IIP2 and DC Offset
Control
DESCRIPTION
n _{400MHz to 4GHz Operating Frequency}
n _{High IIP3: 28.7dBm at 700MHz, 25.7dBm at 1.95GHz}
n _{High IIP2: 70dBm at 700MHz, 60dBm at 1.95GHz}
n _{User Adjustable IIP2 Up to 80dBm}
n _{User Adjustable DC Offset Null}
n _{High Input P1dB: 16dBm at 1950MHz}
n _{I/Q Bandwidth of 530MHz or Higher}
n _{Image Rejection: 43dB at 1950MHz}
n _{Noise Figure: 13.5dB at 700MHz}

12.7dB at 1.95GHz
n _{Conversion Gain: 2.0dB at 700MHz}

2.4dB at 1.95GHz
n _{Single-Ended RF with On-Chip Transformer}
n _{Shutdown Mode}
n _{Operating Temperature Range (TC): –40°C to 105°C}
n _{24-Lead 4mm × 4mm QFN Package}
APPLICATIONS
n _{LTE/W-CDMA/TD-SCDMA Base Station Receivers}
n _{Wideband DPD Receivers}
n _{Point-To-Point Broadband Radios}
n _{High Linearity Direct Conversion I/Q Receivers}
n _{Image Rejection Receivers}
The LTC^®5585 is a direct conversion quadrature demodu-
lator optimized for high linearity receiver applications in
the 400MHz to 4GHz frequency range. It is suitable for
communications receivers where an RF signal is directly
converted into I and Q baseband signals with bandwidth
of 530MHz or higher. The LTC5585 incorporates balanced
I and Q mixers, LO buffer amplifiers and a precision, high
frequency quadrature phase shifter. The integrated on-chip
broadband transformer provides a single-ended interface
at the RF input with simple off-chip L-C matching. In ad-
dition, the LTC5585 provides four analog control voltage
interface pins for IIP2 and DC offset correction, greatly
simplifying system calibration.
The high linearity of the LTC5585 provides excellent spur-
free dynamic range for the receiver. This direct conversion
demodulator can eliminate the need for intermediate fre-
quency (IF) signal processing, as well as the corresponding
requirements for image filtering and IF filtering. These
I/Q outputs can interface directly to channel-select filters
(LPFs) or to baseband amplifiers.
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.
TYPICAL APPLICATION
Direct Conversion Receiver with IIP2 and DC Offset Calibration
5V
BPF
LNA BPF _RF
INPUT RF
V_CC
I^{+ LPF}
VGA
I^–
A/D
LO
LO INPUT
ENABLE
EN
0°
LTC5585
90°
IP2 AND DC
OFFSET CAL
IP2 ADJUST
DC OFFSET
IP2 AND DC
OFFSET CAL
DC OFFSET
IP2 ADJUST
Q^{+ LPF}
VGA
Q^–
D/A
D/A
D/A
D/A
A/D
5585 TA01a
For more information www.linear.com/LTC5585
IIP2 vs IP2I, IP2Q Trim Voltage
120
I, –40°C
Q, –40°C f_RF = 700MHz
110
I, 25°C
I, 85°C
Q, 25°C
Q, 85°C
I, 105°C
Q, 105°C
100
90
80
70
60
50
40
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
IP2I, IP2Q (V)
5585 G09
5585fb
1