A common emitter amplifier having a resistor in series with its emitter and a resistor in series with its collector is temperature stabilized by providing a current source in parallel with the resistor in series with the collector. The current source provides additional emitter current to the transistor to decrease the transistors internal AC emitter resistance. Cascoded transistors are also used to improve the performance of the amplifier.
A gain stabilizing amplifier comprises an amplifying transistor for amplifying an input signal; a node for determining a current flowing into the amplifying transistor; a variable current supply connected to the node, a current output from the variable current supply being set to offset variations in a bias current of the amplifying transistor.
An active circuit includes an amplifying transistor (102), a voltage reference (208), and an active bias circuit. The active bias circuit controls the operating point of the amplifying transistor, and includes a bias transistor (224) which is controlled by the voltage reference and the collector current of the amplifying transistor. As the temperature of the amplifying transistor changes, the tendency of the collector current to change is counter-acted by the bias transistor and the voltage reference.
A metal resistor having a positive temperature coefficient of resistance is connected to a current source to develop a voltage drop that acts as an offset for a .DELTA.V.sub.BE differential amplifier. Since this offset voltage has a positive temperature coefficient it will compensate the resistor coefficient to develop a constant current. The constant current can be employed in a current sink sense-shutoff combination or it can be used to develop a plural output current source/sink combination.
The subject circuit is a converter/isolation circuit which employs only a few components yet functions to monitor a particular signal and produce an output signal which is identical to or proportional to (to a high degree of accuracy) to the monitored input signal. The subject circuit monitors a voltage and generates both a current and a voltage as output signals.
A circuit for generating a reference voltage including a first transistor and a second transistor of which the bases being commonly connected together. The area of the emitter of the first transistor being smaller than the area of the emitter of the second transistor, the emitter of the first transistor being connected to the ground, and the emitter of the second transistor being connected to the ground via a first resistor. The circuit also includes a current supply means which supplies an equal current to the collectors of the first and second transistors and a second resistor which is connected between an output terminal and a connection point of the commonly connected bases of the first and second transistors. The circuit additionally includes a current generator circuit which is connected between the connection point of the commonly connected bases and the ground to produce a current which is proportional to the emitter current of the first transistor or the second transistor, such that a constant voltage is generated at the output terminal.
