SCBA020A October 1999 – March 2020 TMS3705
During receive phase, outputs ANT1 and ANT2 are held at GND. The built-in pre-amplifier operates as internal biased operational amplifier. The resistor ratio of R2/R1 determines the gain factor, which should not be greater than 5. If the gain is higher than 5, the amplifier output can reach its upper limiting area due to the internal DC biasing.