Abstract: A track and hold amplifier for use in adc-converters comprises in succession an input buffer, a pn-junction switch and a hold capacitor. A feedback is provided between the hold capacitor and the input buffer and means are provided to disable the feedback during the hold mode.

Abstract: An A/B class output stage of a signal treating circuit, such as for example a mobile telephone, a radio car kit, other portable equipment, etc. treats a signal. The A/B class output stage drives a load with the signal as treated by the signal treating circuit. The output stage can be connected to one of more than one supply voltages as a function of a voltage value of the signal. The signal treating circuit comprises a D/A converter circuit and a non-linear operating circuit between an input of the signal treating circuit and the D/A converter. Above a certain signal value a change in supply voltage is made. Distortions in an output signal resulting from such a change are prevented by having the non-linear operating circuit generate a jump in DC level at an output of the output stage or raise a value of the signal at a non-clipping one of two output terminals with an extra amount that compensates for the clipping at a clipping one of the two output terminals.

Abstract: In a delta-modulation encoding arrangement having step-size control drift voltages and miss-match between the charge and discharge pulses for the first integrating network in the feedback circuit produce an additional DC voltage on this integrating network. This additional DC voltage is compensated by an additional feedback circuit comprising a second integrating network. However, if the signal to be encoded rapidly decreases from a large to a small amplitude and when after this rapid decrease the information signal only has a small amplitude an additional distortion is introduced for these small signals. To obviate this a modulation arrangement is included in the extra feedback circuit, which modulation arrangement is controlled by a control signal which derives a control signal from the delta modulation output pulses.

Abstract: Transmission system for signal transmission by means of compressed delta modulation provided with leaking integrators in the delta modulator and demodulator, the leaking integrator in the modulator being connected in series with the capacitor of large capacitance between the terminals of a signal source having controlled current sources for reducing the noise and distortion produced by the modulator.