Dear All,
I’m currently designing and evaluating a pulse radar amplifier using the TGA2830. The pulse width is 20-30 uSec, with a duty cycle of 1-2%.
I’m currently encountering an abnormal oscillation issue with the TGA2830 during pulse operation.
I’d appreciate any suggestions for resolving this issue.
The details are as follows:
The oscillation frequency is approximately 400 MHz. Intermodulation occurs between this 400 MHz and an input signal of 3-3.5 GHz.
28V is being supplied to Vd1 and Vd2 of the TGA2830.
Vd1 and Vd2 are directly connected near the input pins.
Oscillation begins when the RF input exceeds +3 dBm.
At frequencies above 3.4 GHz, oscillation begins when the RF input exceeds 6 dBm.
During pulse operation, Vg switches between the pinch-off voltage and operating voltage.
Vg switches approximately 5 uSec before the pulsed RF is raised, and switch to pinch-off approximately 5 uSec after the pulsed RF stops.
When Vg is constantly fixed at the operating voltage, the input level at which abnormal oscillation begins increases by several dB.
Furthermore, when RF is set to CW, the abnormal oscillation stops completely.
Idq is set to 220mA.