Title:
PROTECTION CIRCUIT FOR POWER AMPLIFIER
Document Type and Number:
Japanese Patent JPH0621729
Kind Code:
A
Abstract:
PURPOSE: To protect an output transistor(TR) by surely detecting grounding of an output frame of an IC.
CONSTITUTION: A dummy pad P4 is connected to an output frame F2 via a wire and an emitter of a TRQ3 is connected to the dummy pad P4 via a diode D3. When grounding takes place in the output frame F2 and the potential gets to zero, the dummy pad P4 rapidly reaches 0 potential and an emitter potential of the TRQ3 reaches 1VBE. Then the TRQ3 is turned on, the collector voltage is decreased by a prescribed potential and a switch SW1 is turned off accordingly, then the TRQ1 is turned off. Thus, it is prevented that the TRQ1 is destroyed due to a large current flowing to the TRQ1.
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Inventors:
MATSUSHIMA HISASHI
Application Number:
JP17339792A
Publication Date:
January 28, 1994
Filing Date:
June 30, 1992
Export Citation:
Assignee:
SANYO ELECTRIC CO
International Classes:
H03F1/52; (IPC1-7): H03F1/52
Attorney, Agent or Firm:
Kenji Yoshida (2 outside)
Next Patent: PLASMA TREATING APPARATUS