Texas Instruments TRF370 Series, Руководство пользователя

Страница: 7 / 20

C003
www.ti.com
Overview
Figure 1. Unadjusted Sideband Suppression
1.4.1.2 Optimized Sideband Suppression
The sideband suppression of the TRF370x can be optimized by adjusting the amplitude and phase
balance between the quadrature inputs. The ideal condition is when all four inputs (I, I, Q, and Q) have
exactly the same amplitude and the phase relationship is: I = 0°, I = 180°, Q = 90°, and Q = 270°. Using
an iterative procedure, the gain and phase balance can be adjusted to achieve suppression levels that
exceed 60 dBc. The level of suppression observed depends on the amount of resolution available from
the source driving the modulator. By using TI’s DAC568x, the user can take advantage of built-in features
to optimize the sideband suppression by changing the amplitude and phase relationship of the signals. If
another DAC is used, then the user must provide this level of adjustment by controlling the regular digital
inputs to the DAC. See
Figure 2 .
7 SLWU062 – March 2010 TRF370x Quadrature Modulator Evaluation Module
Submit Documentation Feedback
Copyright © 2010, Texas Instruments Incorporated