LTC5599_15 Datasheet, PDF (1/42 Pages) Linear Technology – 30MHz to 1300MHz Low Power Direct Quadrature Modulator

LTC5599
Features
30MHz to 1300MHz
Low Power
Direct Quadrature Modulator
Description
n _{Frequency Range: 30MHz to 1300MHz}
n _{Low Power: 2.7V to 3.6V Supply; 28mA}
n _{Low LO Carrier Leakage: –51.5dBm at 500MHz}
n _{Side-Band Suppression: –52.6dBc at 500MHz}
n _{Output IP3: 20.8dBm at 500MHz}
n _{Low RF Output Noise Floor: –156dBm/Hz at 6MHz}
Offset, P_RF = 3dBm
n _{Sine Wave or Square Wave LO Drive}
n _{SPI Control:}
Adjustable Gain: –19dB to 0dB in 1dB Steps
Effecting Supply Current from 8mA to 35mA
I/Q Offset Adjust: –65dBm LO Carrier Leakage
I/Q Gain/Phase Adjust: –60dBc Side-Band Suppressed
n _{24-Lead QFN 4mm × 4mm Package}
Applications
n _{Wireless Microphones}
n _{Battery Powered Radios}
n _{Ad-Hoc Wireless Infrastructure Networks}
n _{“White-Space” Transmitters}
n _{Software Defined Radios (SDR)}
n _{Military Radios}
The LTC^®5599 is a direct conversion I/Q modulator de-
signed for low power wireless applications that enable
direct modulation of differential baseband I and Q signals
on an RF carrier. Single side-band modulation or side-band
suppressed upconversion can be achieved by applying
90° phase-shifted signals to the I and Q inputs. The I/Q
baseband input ports can be either AC or DC coupled to a
source with a common mode voltage level of about 1.4V.
The SPI interface controls the supply current, modulator
gain, and allows optimization of the LO carrier feedthrough
and side-band suppression, with sine wave or square
wave LO drive. A fixed LC network on the LO and RF ports
covers a continuous 90MHz to 1300MHz operation. An
on-chip thermometer can be activated to compensate for
gain-temperature variations. More accurate temperature
measurements can be made using an on-chip diode. In
addition, a continuous analog gain control (V_CTRL) pin
can be used for fast power control.
L, LT, LTC, LTM, Linear Technology, and the Linear logo are registered trademarks and
QuikEval is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
Typical Application
90MHz to 1300MHz Direct Conversion Transmitter Application
V_CTRL
SPI
3.3V
1nF + 4.7µF
V_CC
LTC5599
I-DAC
EN
VI
0°
90°
I-CHANNEL
RF = 90MHz
to 1300MHz
10nF
PA
Q-DAC
BASEBAND
GENERATOR
VCO/SYNTHESIZER
VI
39nH
15pF
Q-CHANNEL
THERMOMETER
TTCK
5599 TA01a
For more information www.linear.com/LTC5599
EVM and Noise Floor vs RF Output
Power and Digital Gain Setting
with 1Ms/s 16-QAM Signal
10
9
DG = –19
DG = –16
8
DG = –12
7
DG = –8
6
DG = –4
5
DG = 0
4
3
2
1
0
–105
–115
–125
–135
–145
–155
–15
–10
–5
0
–165
5
RF OUTPUT POWER (dBm)
5599 TA01b
5599f
1