TRF3702_15_15 Datasheet, PDF (23/39 Pages) Texas Instruments – 1.5-GHz to 2.5-GHz QUADRATURE MODULATOR

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TRF3702
SLWS149A – SEPTEMBER 2004 – REVISED AUGUST 2006
TYPICAL CHARACTERISTICS (continued)
NOISE DISTRIBUTION AT 60-MHz
OFFSET OVER TEMPERATURE
20
P_OUT = 0 dBm
18 f_LO = 2.1 GHz
16
14
12
10
8
6
4
2
0
Noise − dBm/Hz
G066
Figure 62.
THEORY OF OPERATION
The TRF3702 employs a double-balanced mixer architecture in implementing the direct I, Q upconversion. The I,
Q inputs can be driven single-endedly or differentially, with comparable performance in both cases. The common
mode level (VCM) of the four inputs (IVIN, IREF, QVIN, QREF) is typically set to 3.7 V and needs to be driven
externally. These inputs go through a set of differential amplifiers and through a V-I converter to feed the
double-balanced mixers. The ac-coupled LO input to the device goes through a phase splitter to provide the
in-phase and quadrature signals that in turn drive the mixers. The outputs of the mixers are then summed,
converted to single-ended signals, and amplified before they are fed to the output port RFOUT. The output of
the TRF3702 is ac-coupled and can drive 50-Ω loads.
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