Abstract: Apparatuses and methods for operating a modulation system using a flexible reference frequency signal are disclosed. A modulation system uses a phase-locked loop (PLL). An internal reference signal source is configured to provide an internal reference signal having an internal frequency that is substantially independent of the reference frequency. A frequency signal source is configured to provide a plurality of first samples of the frequency signal taken at a first sampling frequency according to the internal reference signal. A resampling device is configured to receive and resample the plurality of first samples to generate a plurality of second samples taken at a second sampling frequency according to the reference frequency. A loop gain compensation device is configured to receive the reference frequency and apply an offset gain to inversely offset a change in PLL loop gain responsive to a change in the reference frequency.

Abstract: The invention relates to an differential amplifier circuit comprising an amplifier stage comprising a first and a second transistor, the gates of which are connected to differential input terminals of the amplifier stage. The differential amplifier further comprises a temperature compensation circuit comprising a third and fourth transistor. The third transistor is connected to the source of the first transistor and the fourth transistor is connected to the source of the second transistor. Further, the temperature compensation circuit comprises a constant current source connected to the respective sources of the third and fourth transistors. Thereby the temperature compensation circuit is arranged to provide a feedback resistance in dependence on the operating temperature so as to compensate for variations of the resistance of the first and second transistors.

Abstract: Apparatuses and methods for operating a modulation system using a flexible reference frequency signal are disclosed. A modulation system uses a phase-locked loop (PLL). An internal reference signal source is configured to provide an internal reference signal having an internal frequency that is substantially independent of the reference frequency. A frequency signal source is configured to provide a plurality of first samples of the frequency signal taken at a first sampling frequency according to the internal reference signal. A resampling device is configured to receive and resample the plurality of first samples to generate a plurality of second samples taken at a second sampling frequency according to the reference frequency. A loop gain compensation device is configured to receive the reference frequency and apply an offset gain to inversely offset a change in PLL loop gain responsive to a change in the reference frequency.

Abstract: The invention relates to an differential amplifier circuit comprising an amplifier stage comprising a first and a second transistor, the gates of which are connected to differential input terminals of the amplifier stage. The differential amplifier further comprises a temperature compensation circuit comprising a third and fourth transistor. The third transistor is connected to the source of the first transistor and the fourth transistor is connected to the source of the second transistor. Further, the temperature compensation circuit comprises a constant current source connected to the respective sources of the third and fourth transistors. Thereby the temperature compensation circuit is arranged to provide a feedback resistance in dependence on the operating temperature so as to compensate for variations of the resistance of the first and second transistors.

Abstract: A circuit arrangement for regulating a parameter (e.g., duty cycle) of an electrical signal, generated by a circuit component. The regulating device includes a first integrator, which is supplied with the output signal from the circuit component, and a second integrator, which is supplied with the output signal from the first integrator. The second integrator has an operational amplifier having an inverting input, a noninverting input and an output, and the output is fed back to the inverting input via a feedback path. The inverting input receives the output signal from the first integrator. The noninverting input receives a reference signal. The output of the operational amplifier is fed back to the inverting input via a series circuit including a capacitor and a resistor. The output of the second operational amplifier provides an output signal from the regulating device, which is supplied to the circuit component as a controlled variable.

Abstract: A circuit arrangement for regulating the duty cycle of an electrical signal including a first input differential amplifier, to which an input signal is applied; a first current source for controlling the current through the first input differential amplifier; a second input differential amplifier, to which the same input signal is applied; a second current source for controlling the current through the second input differential amplifier; a device which generates a fluctuating voltage signal from output signals of the two input differential amplifiers; a buffer device, which converts the fluctuating voltage signal into a digital output signal; a capacitance and a device for charging and discharging the capacitance in time with the digital output signal. The voltage present at the capacitance is fed to the first and second current sources as control voltage and effects regulation of the two current sources in opposite senses.

Abstract: A circuit arrangement for regulating a parameter (e.g., duty cycle) of an electrical signal, generated by a circuit component. The regulating device includes a first integrator, which is supplied with the output signal from the circuit component, and a second integrator, which is supplied with the output signal from the first integrator. The second integrator has an operational amplifier having an inverting input, a noninverting input and an output, and the output is fed back to the inverting input via a feedback path. The inverting input receives the output signal from the first integrator. The noninverting input receives a reference signal. The output of the operational amplifier is fed back to the inverting input via a series circuit including a capacitor and a resistor. The output of the second operational amplifier provides an output signal from the regulating device, which is supplied to the circuit component as a controlled variable.

Abstract: Optical receiver circuit having a first, illuminable reception device for converting an optical signal into an analog electrical signal; a first preamplifier for amplifying the output signal of the first reception device; a postamplifier having a first input and a second input, the first input being supplied with the signal of the first reception device (said signal having been amplified in the first preamplifier) and the second input being supplied with a reference signal; an offset compensation circuit, which regulates the difference between the mean value of the electrical signal at the first input of the postamplifier and the reference signal at the second input of the postamplifier to a constant value; and having a signal detection device, which detects a control signal of the offset compensation circuit and carries out signal detection in a manner dependent on this signal. The invention provides signal detection in an optical receiver circuit, which manages with few additional components.

Abstract: Optical receiver circuit having a first, illuminable reception device for converting an optical signal into an analog electrical signal; a first preamplifier for amplifying the output signal of the first reception device; a postamplifier having a first input and a second input, the first input being supplied with the signal of the first reception device (said signal having been amplified in the first preamplifier) and the second input being supplied with a reference signal; an offset compensation circuit, which regulates the difference between the mean value of the electrical signal at the first input of the postamplifier and the reference signal at the second input of the postamplifier to a constant value; and having a signal detection device, which detects a control signal of the offset compensation circuit and carries out signal detection in a manner dependent on this signal. The invention provides signal detection in an optical receiver circuit, which manages with few additional components.

Abstract: A circuit arrangement for regulating the duty cycle of an electrical signal including a first input differential amplifier, to which an input signal is applied; a first current source for controlling the current through the first input differential amplifier; a second input differential amplifier, to which the same input signal is applied; a second current source for controlling the current through the second input differential amplifier; a device which generates a fluctuating voltage signal from output signals of the two input differential amplifiers; a buffer device, which converts the fluctuating voltage signal into a digital output signal; a capacitance and a device for charging and discharging the capacitance in time with the digital output signal. The voltage present at the capacitance is fed to the first and second current sources as control voltage and effects regulation of the two current sources in opposite senses.