Texas Instruments TRF1500 - Manual (Page 17)

SWRA004A
18 TRF1500 Integrated Dual-Band RF Receiver User’s Guide
Low Band Cascaded Receiver Section: LNA, External SAW
Filter, Mixer, and LO Buffer Amplifier
The TRF1500 low-band receiver section, shown in Figure 2, is an
integrated front-end down converter designed to operate in the
800 MHz frequency range. The low-band down converter consists
of an LNA, mixer, LO buffer amplifier and an off-chip image reject
filter. The digital control allows the low-band to operate in three
different states to compensate for the environment in which the
TRF1500 is operating. The device 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 low-band receiver has low typical current consumption of
21mA at 3.75V supply. The cascaded gain is typically 26dB while
providing good dynamic range with approximately a -10dBm third
order input intercept point (IIP3). The low-band receiver has a
typical system noise figure of approximately 2.5 dB for excellent
sensitivity.
Figure 2. Cascaded Block Diagram of the Low-Band Receiver Section