Supply voltage sense amplifier
First Claim
1. A temperature-compensated supply voltage sense amplifier comprising:
- a first transistor circuit including a transistor means having a positive temperature coefficient of current for providing a positive temperature coefficient current in which the current increases with increasing temperature;
a second transistor circuit including a transistor means having a negative temperature coefficient of base-to-emitter voltage;
a third transistor circuit including transistors means forming a current mirror coupled between said first and said second transistor circuits for transferring said positive temperature coefficient current from said first transistor circuit into said second transistor circuit; and
a resistance means coupled between said third transistor circuit and said second transistor circuit for establishing a constant reference voltage at a first node between said resistance means and said current mirror, the magnitude of which is independent of temperature.
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Accused Products
Abstract
A temperature-compensated reference voltage circuit includes a transistor having a positive temperature coefficient of current. A circuit for establishing a predetermined current in the positive-temperature-coefficient-of-current transistor is connected to that transistor. A predetermined resistance serially connects the positive-temperature-coefficient-of-current transistor with a transistor having negative temperature coefficient of base-to-emitter voltage. The temperature-compensated reference voltage is established between the transistors. The temperature-compensated reference voltage circuit is particularly useful in a supply voltage sense amplifier circuit for thermal printhead drive transistors or other load elements. The sense amplifier circuit includes a circuit for comparing the reference voltage and a supply voltage. An output is adapted to be connected to a load for receiving the supply voltage. A circuit is connected to receive an input from the comparing circuit, and to said output, for enabling the output when the supply voltage is equal or greater than the reference voltage.
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Citations
12 Claims
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1. A temperature-compensated supply voltage sense amplifier comprising:
- a first transistor circuit including a transistor means having a positive temperature coefficient of current for providing a positive temperature coefficient current in which the current increases with increasing temperature;
a second transistor circuit including a transistor means having a negative temperature coefficient of base-to-emitter voltage; a third transistor circuit including transistors means forming a current mirror coupled between said first and said second transistor circuits for transferring said positive temperature coefficient current from said first transistor circuit into said second transistor circuit; and a resistance means coupled between said third transistor circuit and said second transistor circuit for establishing a constant reference voltage at a first node between said resistance means and said current mirror, the magnitude of which is independent of temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- a first transistor circuit including a transistor means having a positive temperature coefficient of current for providing a positive temperature coefficient current in which the current increases with increasing temperature;
Specification