Composite audio amplifier
First Claim
1. A composite audio amplifier comprising at least one symmetrical, dual polarity audio amplifier power supply and a class AB audio amplifier circuit, said symmetrical, dual polarity audio amplifier power supply comprisingfirst positive and negative and second positive and negative unregulated DC inputs;
- positive and negative regulated outputs and a common output;
a first and a second regulator circuit;
said first regulator circuit including at least one pass transistor having its emitter connected to said first negative unregulated DC input and its collector connected to said common ouput, said second regulator circuit including at least one pass transistor having its emitter connected to said positive unregulated DC input and its collector connected to said common output;
each said pass transistor having a pass resistor connected between the emitter and collector of said pass transistor;
said first regulator circuit deriving a reference signal from said negative regulated output and said second regulator circuit deriving a reference from said positive regulated output;
said first and second regulator circuit deriving power from said positive regulated output and common and said negative regulated output and common respectively;
said class AB audio amplifier circuit comprising in combinationa primary operational amplifier driving complementary power transistor output stages;
bias current for said complementary power transistor output stages including bias current adjustment means to adjust said bias current in response to the temperature of at least one of a power transistor forming part of said complementary power transistor output stages;
the signal output of said primary operational amplifier being fed to complementary symmetric first and second arms of a current shunt network, said current shunt network adapted to shunt base current from said complementary power transistor output stages when said signal output of said primary operational amplifier exceeds a preset maximum threshold and, at the same time, said signal from said power output drops below a preset minimum threshold;
said current shunt network adapted to allow transient overload conditions.
1 Assignment
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Accused Products
Abstract
Audio amplifier comprising symmetrical, dual polarity power supply and class AB audio amplifier circuit, said supply comprising first positive (86) and negative (85) and second positive (83) and negative (84) unregulated DC inputs; positive and negative regulated outputs and common output (87); first regulator circuit including transistor (62) having its emitter connected to said first negative unregulated DC input; a second regulator circuit including transistor (61) having its emitter connected to said positive unregulated DC input and both collectors connected to said common output, each transistor having a pass resistor, said first circuit deriving a reference from said negative regulated output and said second circuit deriving a reference from said positive regulated output said first and second regulator circuit deriving power from said positive regulated output and common and said negative regulated output and common respectively; said amplifier circuit comprising primary operational amplifier (12) driving complementary power transistor output stages (9, 10); bias adjustment means responsive to temperature of the output stages; the signal output of said operational amplifier being fed to complentary symmetric arms of a network shunting base current from said output stages when said signal exceeds a threshold and, at the same time, said power output drops below a threshold; said network allowing transient overloads.
4 Citations
13 Claims
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1. A composite audio amplifier comprising at least one symmetrical, dual polarity audio amplifier power supply and a class AB audio amplifier circuit, said symmetrical, dual polarity audio amplifier power supply comprising
first positive and negative and second positive and negative unregulated DC inputs; -
positive and negative regulated outputs and a common output; a first and a second regulator circuit; said first regulator circuit including at least one pass transistor having its emitter connected to said first negative unregulated DC input and its collector connected to said common ouput, said second regulator circuit including at least one pass transistor having its emitter connected to said positive unregulated DC input and its collector connected to said common output; each said pass transistor having a pass resistor connected between the emitter and collector of said pass transistor; said first regulator circuit deriving a reference signal from said negative regulated output and said second regulator circuit deriving a reference from said positive regulated output; said first and second regulator circuit deriving power from said positive regulated output and common and said negative regulated output and common respectively; said class AB audio amplifier circuit comprising in combination a primary operational amplifier driving complementary power transistor output stages; bias current for said complementary power transistor output stages including bias current adjustment means to adjust said bias current in response to the temperature of at least one of a power transistor forming part of said complementary power transistor output stages; the signal output of said primary operational amplifier being fed to complementary symmetric first and second arms of a current shunt network, said current shunt network adapted to shunt base current from said complementary power transistor output stages when said signal output of said primary operational amplifier exceeds a preset maximum threshold and, at the same time, said signal from said power output drops below a preset minimum threshold; said current shunt network adapted to allow transient overload conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification