OVERVIEW: Transmitter Path Section
The forward path includes the following:
• SLEDGEHAMMER
• JANUS (Balun, Power amplifier, Coupler)
The feedback path includes the following:
• Coupler
• Feedback attenuation network.
• SLEDGEHAMMER
1.7.5 Level Set and Phase Training
Level set training is performed to ensure that the RF PA is not driven into clip, which would result
in excess splatter and out-of-band spurious emissions. During training, the DSP signal is
disconnected from the forward path and an internal analog ramp generator is connected. The
feedback is monitored and compared to the analog ramp. As the ramp amplitude increases and the
RF PA begins to clip, the error voltage increases. See Figure 1-16 on page 33.
The Javelin levelset circuit topology is modified slightly for Sledgehammer. The major difference
is that switches are not provided to select the I-channel training waveform to the Q-channel V-I
input. Instead, a programmable gain V-I is specified below on the Ichannel for boosting the
reference signal level during level training. The "cnrmp" control signal is output from the levelset
circuit to the I-channel V-I to control when the gain is changed.
V_TERM is a new signal input that will be OR'ed with the clip comparator output. This signal
causes a controlled signal ramp down when the battery current exceeds 3A during level training.
V_TERM OR'ed with the clip comparator output is sent back to the digital core to terminate the
counter used for the LEVEL _TRAIN read back value
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