Texas Instruments TRF1500 - Manual (Page 34)

SWRA004A
TRF1500 Integrated Dual-Band RF Receiver User’s Guide 35
High-Band Cascaded Receiver Section: LNA, Mixer, LO
Buffer Amplifier
Cascaded High-Band Receiver Section: LNA, Mixer, and LO Amplifier
The TRF1500 high-band receiver section, shown in Figure 11, is
an integrated front-end down converter designed to operate in the
1900 MHz frequency range. The high-band down converter
consists of an LNA, an image-reject mixer, and LO buffer amplifier
circuitry. Figure 11 details the cascaded block diagram with the
image reject mixer detailed inside the dotted box.
The digital control allows the high-band receiver to operate in
three different states to compensate for the environment in which
the TRF1500 is operating. The high-band receiver can be
operated in the normal state, where the LNA, mixer and buffer
amplifier are on, the strong signal state, where the LNA is off and
the mixer and buffer amplifier are on, or the transmit state, where
the LNA bias current is increased to prevent compression when
the transmitter is on.
The high-band receiver has a typical nominal gain of 26 dB, an
IIP3 of -17.7 dBm and a noise figure of 4.66 dB when the receiver
LO doubler is used and 4.35 dB when the high-band LO is directly
driven.
Figure 11. Block Diagram of the High-Band Receiver Section