Floating power supply using dual npn transistor
AssigneeYoungtek Electronics Corporation
InventorAngus Chen
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Abstract
A low supply voltage for operating an operational amplifier operating as a voltage follower is derived from a high voltage source. Two npn transistors, two Zener diodes and a current source are connected in series across the high voltage source. The input voltage (to the operational amplifier) plus a Zener reference voltage is applied to the base of the transistor near the positive terminal of the high voltage source. Then, a low positive supply voltage V+ nearly equal to the input voltage plus the Zener voltage (Vi+Vz) is derived at the emitter. This low positive supply voltage V− is derived by dropping V+ through the two series Zener diodes to obtain a low negative supply voltage equal to (Vi−Vz).
Claims8
A low voltage floating power supply derived a high voltage source, comprising:
- a positive high voltage source;
- a negative high voltage source,
- an input voltage;
- a first npn transistor with a collector connected to said positive high voltage source;
- a first Zener diode with cathode connected to the emitter of said first npn transistor;
- a second Zener diode with cathode connected to the anode of said first Zener diode;
- a second npn transistor with collector connected the anode of said second Zener diode,
- a current source for sinking the emitter current of said second npn transistor to said negative high voltage source;
- a bias regulator to add a fixed bias to the input voltage for biasing the base of said first npn transistor,
- a positive supply voltage obtained at the emitter of said first npn transistor;
- a negative supply voltage obtained at the collector of said second npn transistor.
Dependencies are inferred from the claim text.