Amplification circuit

An amplification circuit comprising:

• power amplifying means for amplifying an input signal, the power amplifying means capable of being driven by receiving a source voltage;
• a power source;
• main power source supplying means for supplying a source voltage from said power source to said power amplifying means,
• said power source supplying means comprising,
• a switching element, provided between said power amplifying means and said power source, for switching transmission of said power source voltage to said power amplifying means,
• smoothing means for smoothing a switching output through the switching element and
• switching control means for controlling a switching operation of the switching element;
• auxiliary power source supplying means for supplementing a deficiency of said source voltage to permit the power amplifying means to be driven normally;
• wherein said switching control means comprises current detection means and a hysteresis comparator, the current detection means for detecting a current flowing through said auxiliary power source supplying means and the hysteresis comparator for controlling an on/off timing of the switching element in accordance with detected current of said current detection means.

A power source supplying system for a power amplifier comprising:

• a power source;
• high efficiency current buffer means for supplying power having a high efficiency current characteristic from said power source to the power amplifier;
• high speed voltage buffer means for supplying power having a high speed voltage characteristic from said power source to the power amplifier;
• current detection means provided between said power source and said high speed voltage buffer means for detecting a current flowing from said high speed voltage buffer means to the power amplifier;
• and
• control means for controlling output of said high efficiency current buffer means in response to said current detected by said current detection means.

A power source supplying device for a power amplifier comprising:

• a power source;
• a switching transistor, an emitter of which is connected to the power source;
• a smoothing circuit connected to a collector of the switching transistor;
• a hysteresis comparator, an output side of which is connected to a base of the switching transistor, the hysteresis comparator outputting a control voltage having a hysteresis characteristic;
• current detection resistor, one end of which is connected to the power source and the other end of which is connected to the input side of the hysteresis comparator;
• a transistor, a collector of which is connected to the input side of said hysteresis comparator and an emitter of which is connected to the output side of said smoothing circuit;
• and
• an output stage transistor for supplying power to drive a load, a collector of which is connected to a connection point of said transistor and said smoothing circuit,
• wherein a base of the transistor and an emitter of the output stage transistor are connected so as to have a predetermined potential difference between each other.