Model 250S1G6
26
Rev D
3.2.2
A2, A4-A7 Driver Amps (Schematic 10036226, 10028316,
10033603)
The Driver Amp RF section is assembled on thin film substrates and the bias control and fault circuitry is
assembled on a multi-layer printed circuit board. It has two (2) GaN amplifier sections. Each section is input
and output DC isolated by coupling capacitors. A 90
˚
quad coupler combines the RF outputs. 50Ω
termination resistors absorb any difference signals and help to improve the input and output VSWR of the
module. The module has a gain of approximately 10dB and delivers 10-15 watts of RF power. Active bias
circuitry regulates the DC current through RF devices. The nominal DC current for this amplifier is
approximately 3.0A from a 24.5V supply. Logic low voltage on the fault pin indicates a low or high current
condition exists on GaN FET 1 (bottom) or FET 2 (top).
3.2.3
A12 through A27 Output Power Amplifiers (Schematic
10036226, 10028316, 10033603)
The output power amplifiers are identical in construction and performance to the driver amplifiers described
in 3.2.2.
3.2.4
A3, A8 through A11 Four-Way Splitter
The Four-Way splitter is a multi-section, broadband, Wilkinson splitter. The input signal is split into four
equal-amplitude, equal-phase signals. The amplitude of each signal is 6–6.5dB below the input signal when
both outputs are terminated into 50Ω lo
ads.
3.2.5
A28 Sixteen-Way Combiner
A28 is a Sixteen-Way radial combiner with impedance-matching. When the outputs of the 16 quad amplifiers
are fed to the 16-way combiner, the combined output will be approximately 12dB above the output of a single
quad amplifier.
