Texas Instruments TRF1500 用户手册
SWRA004A
50
TRF1500 Integrated Dual-Band RF Receiver User’s Guide
Low-Band and High-Band Transmit
Low- and High-Band Transmit Mixer
Figure 17 details the block diagram of the transmit mixer. The
TRF1500 provides a transmit mixer for down converting the
system transmit signal (low-band or high-band) to a common IF
for loop-back testing. The LO input for this mixer can be selected
from either the low-band LO input or the high-band LO input by
means of the digital control. The RF input of the transmit mixer
provides a broad-band 200
TRF1500 provides a transmit mixer for down converting the
system transmit signal (low-band or high-band) to a common IF
for loop-back testing. The LO input for this mixer can be selected
from either the low-band LO input or the high-band LO input by
means of the digital control. The RF input of the transmit mixer
provides a broad-band 200
Ω
differential input impedance over a
band of 800 MHz to 2GHz and thus requires minimal external
matching.
matching.
The mixer is a double-balanced Gilbert cell design with open
collector outputs. The Gilbert cell structure was implemented for
its robust isolation and harmonic suppression characteristics.
collector outputs. The Gilbert cell structure was implemented for
its robust isolation and harmonic suppression characteristics.
Figure 17. Transmit Mixer Block Diagram
Low-Band and High-Band Transmit Mixer RF Input
Figure 18 details the transmit mixer RF input configuration. The
transmit mixer can be either driven single-ended or differentially.
For evaluation purposes, a 4:1 transformer balun is used on the
EVM to drive the transmit mixer single-ended. The input requires
very little external matching. A shunt capacitor (C35) near the
input port (J30) and a shunt capacitor (C36) near the transformer
balun (T30) are the only input impedance matching components
required.
transmit mixer can be either driven single-ended or differentially.
For evaluation purposes, a 4:1 transformer balun is used on the
EVM to drive the transmit mixer single-ended. The input requires
very little external matching. A shunt capacitor (C35) near the
input port (J30) and a shunt capacitor (C36) near the transformer
balun (T30) are the only input impedance matching components
required.