Deutsche Thomson-brandt Gmbh

Joachim Lange

Gerhard Maier

Bertram Fischer

A printed circuit board includes an oscillator and a modulator. The oscillator includes a first printed inductor and a capacitive diode which are printed on one side of the printed circuit board. The modulator includes a second printed inductor coupled to the first printed inductor and printed on the same side of the printed circuit board as the oscillator. A conductive surface at a reference potential is arranged the other side of the printed circuit board and in the vicinity of the oscillator and the modulator and electrically coupled to the oscillator and the modulator using conductive through holes.

Oscillator and modulator arrangements on a circuit board

A circuit is provided for the measurement and recognition of maximum or minimum voltages coming for example from a frequency selective measurement objective and in particular from an electronic filter. A fixed measurement frequency is fed to the measurement object. The measurement object is balanced by a stepwise change of a tuning voltage. The output voltage generated by the measurement object is fed to a switch after rectification and amplification, which switch is clocked with a clock signal. The output voltages of the switch are fed to an intermediate storage. The output voltages of the intermediate storage are supplied to a differential amplifier via an intermediate switch actuated by a control clock cycle. If the output voltage reaches an extremum such as a maximum then the stepwise change of the tuning voltage is interrupted. The value determined for the tuning voltage is stored in a memory such as a random access memory, the contents of which represents the optimum for the tuning of the measurement object such as for example the filter.

Circuit for the determination of voltage extrema

An tuner unit is provided for communications receivers with automatic self-balancing of the individual high frequency filter circuits. An assigned frequency applied to the desired receiver channel is fed to the antenna input during the automatic balancing process. The voltage of this assigned frequency picked up at the output of the filter circuits changes according to a stepwise increase of a tuning voltage controlled by a microprocessor. The tuning voltage is applied to the filter circuit to be balanced via a digital-analog converter and via a switching means controlled by the microprocessor. The automatic balancing is provided by switching the switching means successively to connect to the individual filter sections.

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Villingen-Schwenningen, Germany

Joachim Lange