U.S. Philips Corporation

Gert F Bierkarre

Holger Gehrt

Karl-Heinz Matthies

Joachim Utzig

Wolfgang Schnitt

A circuit arrangement for supplying a constant current which is stabilized against temperature variations. The constant current is produced by a current source which is controlled by a control stage in which a first control current is supplied to each of a first and a second resistor, at least one of which is trimmable. The first control current is controlled so that the difference between the voltages produced thereby across the first and second resistors is in a first predetermined ratio to the constant voltage produced by a reference voltage source. The current source is controlled by the control stage so that the constant current produced thereby is in a second predetermined ratio to the first control currents.

Constant current supply circuit with stabilization based on voltage and

The invention relates to a modulator comprising a first differential amplifier (6) which receives an input signal and a correction signal for adjusting the quiescent currents on the first and second output. The first differential amplifier (6) is coupled to a second differential amplifier (19) and a third differential amplifier (22), which receive the carrier signal and which supply the modulated signal. A difference signal proportional to the difference between the current of the first output and the current of the second output of the first differential amplifier (40) is applied to a low-pass filter (25), whose output signal is applied to a control amplifier (40). The control amplifier (40) supplies the correction signal to the second input of the first differential amplifier (6) via a storage device (50).

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Escheburg, Germany

Gert F Bierkarre