Abstract: The present invention relates to an electronic device that includes an integrated power comparator circuit (1) for a self-oscillating class D system (100). The integrated power comparator circuit (1) has a modulation stage (10), wherein the modulation stage (10) comprises a compensation circuit (40) for providing a compensation signal to the modulation stage, which is dimensioned for compensating a variation of a process parameter for smoothing initialization of the self-oscillating class D system (100).

Abstract: An amplifier circuit in which a first amplifier (A1) and a second amplifier (A2) are protected against short-circuits by a protection apparatus which includes a first device (M1), a second device (M2), a third device (M3) and a protection device (B). For this purpose the first device and the second device generate four signals (s1, s2, s3, s4) related to an equal number of currents (i1, i2, i3, i4), which currents are related to a first or a second load current in the first amplifier or in the second amplifier. In order to control the protection device (B), the third device generates at least two control signals (r1, r2) related to the signal currents (s1, s2, s3, s4), use being made of the equality of the load currents in the absence of short-circuits.

Abstract: An input signal (Vin) is applied to a first amplifier (A1) and a second amplifier (A2) via a circuit (M), which amplifiers are both coupled to an output terminal (U) to supply an output voltage (Vuit). For this purpose the circuit (M) generates two mutually complementary signals which are related to the output signal (Vuit) and the maximum signal values corresponding to the individual output signals of the first amplifier (A1) and the second amplifier (A2). The output signal to be supplied (Vuit) consequently dictates which amplifier (A1, A2) is driven into full conduction.

Abstract: In order to boost the output power of a first amplifier (A1) a second amplifier (A2) can increase the supply voltage difference across the first amplifier (A1). However, variations of the supply voltage difference result in comparatively high distortion. In order to minimize this distortion while maintaining the output power, a signal-follower circuit generates a direct voltage lever which tracks a first output signal of the first amplifier, for which purpose the signal-follower circuit is driven by a third amplifier, which compares the first output signal with a reference signal.

Abstract: An integrated current-mirror arrangement comprises a first and a second transistor whose bases are interconnected and connected to the collector of the first transistor. The transistors are constructed as vertical transistors each having a collector region (23a, 23b) of the first conductivity type, isolated from the substrate (21) of the first conductivity type by an intermediate layer (22) of the second conductivity type. A connection is provided between said intermediate layer (22) and the interconnected bases (29, 30) of the two transistors which improves the high-frequency transfer function between input and output and effectively eliminates the capacitive path for interference signals from the voltage supply line (+V) to the output.

Abstract: The first (T.sub.1) and the second (T.sub.2) output transistor of an amplifier arrangement are push-pull driven by means of a drive circuit (10) having two transistors (T.sub.11, T.sub.12) which are each loaded by a current source (T.sub.13, T.sub.14). Currents which are a measure of the currents flowing through the first (T.sub.1) and the second (T.sub.2) output transistor are generated by first (20) and second (30) current measuring means. These currents are applied to a negative feedback means (40) which controls the current intensity of the current sources (T.sub.13, T.sub.14) in such a way that the harmonic mean value of the currents flowing through the first (T.sub.1) and the second (T.sub.2) output transistor is substantially equal to a reference value.