Derived power supply for composite bridge amplifiers
First Claim
1. An amplifier for amplifying an input signal, said amplifier comprising:
- (a) a signal input terminal for receiving said input signal;
(b) a safety isolation circuit coupled to said signal input terminal and having an isolated signal terminal, said safety isolation block being adapted to provide a physical isolation between said signal input terminal and said isolated signal terminal and being adapted to provide a signal corresponding to said input signal at said isolated signal terminal;
(c) a signal amplifier block having first and second voltage input terminals and a control terminal, said control terminal being coupled to said isolated signal terminal;
(d) an AC power rectification block for providing a fixed DC voltage at first and second DC voltage terminals;
(e) an amplifier power supply block coupled to said first and second DC voltage terminals for producing at said first and second voltage input terminals a time-varying non-ground referenced DC voltage dependent on said input signal;
(f) an amplifier power control circuit coupled to said signal input terminal and said amplifier power supply block for controlling said time-varying non-ground referenced DC voltage;
(g) a startup block adapted to automatically generate a startup signal when said amplifier is initially energized and coupled to said amplifier power control circuit, said amplifier power control circuit being responsive to said startup signal to control said amplifier power supply block such that said amplifier power supply block produces a fixed non-ground referenced DC voltage at said first and second voltage input terminals for a selected period of time;
(h) an electronics power supply circuit having first and second fixed DC voltage output terminals, said electronics power supply circuit being coupled to said first and second voltage input terminals for receiving said time-varying non-ground referenced DC voltage and for producing a fixed DC voltage at said first and second DC voltage output terminals from said time-varying non-ground referenced DC voltage.
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Accused Products
Abstract
A composite bridge amplifier in which the power supply for the bridge amplifiers includes a time varying non-ground reference DC voltage supply dependant on the input signal. A low voltage power supply circuit uses the time varying non-ground reference DC voltage to produce a fixed DC voltage and includes a centering block which removes unbalanced DC voltages which might otherwise contaminate the time varying non-ground reference DC voltage, by providing balancing currents. This eliminates a costly transformer. Safety isolation is provided using an isolation amplifier with a transformer which has a parasitic capacitance. Improved common mode noise rejection is provided by configuring the isolation amplifier so that currents charging the parasitic capacitance with common mode noise voltage tend to cancel noise current in the secondary winding of the transformer.
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Citations
14 Claims
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1. An amplifier for amplifying an input signal, said amplifier comprising:
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(a) a signal input terminal for receiving said input signal; (b) a safety isolation circuit coupled to said signal input terminal and having an isolated signal terminal, said safety isolation block being adapted to provide a physical isolation between said signal input terminal and said isolated signal terminal and being adapted to provide a signal corresponding to said input signal at said isolated signal terminal; (c) a signal amplifier block having first and second voltage input terminals and a control terminal, said control terminal being coupled to said isolated signal terminal; (d) an AC power rectification block for providing a fixed DC voltage at first and second DC voltage terminals; (e) an amplifier power supply block coupled to said first and second DC voltage terminals for producing at said first and second voltage input terminals a time-varying non-ground referenced DC voltage dependent on said input signal; (f) an amplifier power control circuit coupled to said signal input terminal and said amplifier power supply block for controlling said time-varying non-ground referenced DC voltage; (g) a startup block adapted to automatically generate a startup signal when said amplifier is initially energized and coupled to said amplifier power control circuit, said amplifier power control circuit being responsive to said startup signal to control said amplifier power supply block such that said amplifier power supply block produces a fixed non-ground referenced DC voltage at said first and second voltage input terminals for a selected period of time; (h) an electronics power supply circuit having first and second fixed DC voltage output terminals, said electronics power supply circuit being coupled to said first and second voltage input terminals for receiving said time-varying non-ground referenced DC voltage and for producing a fixed DC voltage at said first and second DC voltage output terminals from said time-varying non-ground referenced DC voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification