Abstract: A power supply system comprises a parallel arrangement of a linear amplifier (LA) and a DC-DC converter (CO). An output of the linear amplifier (LA) is directly coupled to a load (LO) for supplying a first current (II) to the load (LO). The DC-DC converter (CO) has a converter output coupled to the load (LO) for supplying a second current (12) to the load (LO). The linear amplifier (LA) comprises a first amplifier stage (OS1) to supply the first current (II), and the second amplifier stage (OS2) to generate a third current (13) being proportional to the first current (II). The first amplifier stage (OS1) and the second amplifier stage (OS2) have matched components. The DC-DC converter (CO) further comprises a controller (CON) having a control input for receiving a voltage generated by the third current (13) to control the second current (12) for minimizing a DC-component of the first current (II).

Abstract: The present invention relates to an improved PTAT current source and a respective method for generating a PTAT current. Opportune collector currents are generated and forced in two transistors exploiting the logarithmic relation between the base-emitter voltage and the collector current of a transistor. A resistor senses a voltage difference between the base-emitter voltages of the two transistors, which can have either the same or different areas. A fraction of the current flowing through the resistor is forced into a transistor collector and mirrored by an output transistor for providing an output current. By this principle an all npn-transistor PTAT current source can be provided that does not need pup transistors as in conventional PTAT current sources. The invention is generally applicable to a variety of different types of integrated circuits needing a PTAT current reference, especially in modern advanced technologies as InP and GaAs where p-type devices are not available.

Abstract: A controller (1) comprises a comparator (10) which compares an input signal (Vo) with a reference signal (Vr) to obtain an error signal (ER). An integrator (11) applies an integrating action on the error signal (ER) to obtain a control signal (ICO). The integrator (11) allows influencing the integrating action. A copy circuit (81) supplies a copy control signal (ICOC) being proportional to the control signal (ICO). A determination circuit (85) determines whether the copy control signal (ICOC) reaches a limit value (IMIN, IMAX). An influencing circuit (83) influences the integrating action to limit the control signal (ICO) when the copy control signal (ICOC) reaches the limit value (IMIN, IMAX).

Abstract: A power supply system comprises a parallel arrangement of a linear amplifier (LA) and a DC-DC converter (CO). The linear amplifier (LA) has an amplifier output to supply a first current (II) to the load (LO). The DC-DC converter (CO) comprises: a converter output for supplying a second current (12) to the load (LO), a first inductor (L1), and a switch (SC) coupled to the first inductor (L1) for generating a current in the first inductor (L1), and a low-pass filter (FI) arranged between the first inductor (L1) and the load (LO). The low pass filter (FI) comprises a first capacitor (C1; CA) which has a first terminal coupled to the switch (SC) an a second terminal coupled to a reference voltage level (GND), and a second inductor (L2; LC) which has a first terminal coupled to the first inductor (L1) and a second terminal coupled to the load (LO).

Abstract: The present invention relates to an improved PTAT current source and a respective method for generating a PTAT current. Opportune collector currents are generated and forced in two transistors exploiting the logarithmic relation between the base-emitter voltage and the collector current of a transistor. A resistor senses a voltage difference between the base-emitter voltages of the two transistors, which can have either the same or different areas. A fraction of the current flowing through the resistor is forced into a transistor collector and mirrored by an output transistor for providing an output current. By this principle an all npn-transistor PTAT current source can be provided that does not need pup transistors as in conventional PTAT current sources. The invention is generally applicable to a variety of different types of integrated circuits needing a PTAT current reference, especially in modern advanced technologies as InP and GaAs where p-type devices are not available.

Abstract: A power supply system comprises a parallel arrangement of a linear amplifier (LA) and a DC-DC converter (CO). An output of the linear amplifier (LA) is directly coupled to a load (LO) for supplying a first current (II) to the load (LO). The DC-DC converter (CO) has a converter output coupled to the load (LO) for supplying a second current (12) to the load (LO). The linear amplifier (LA) comprises a first amplifier stage (OS1) to supply the first current (II), and the second amplifier stage (OS2) to generate a third current (13) being proportional to the first current (II). The first amplifier stage (OS1) and the second amplifier stage (OS2) have matched components. The DC-DC converter (CO) further comprises a controller (CON) having a control input for receiving a voltage generated by the third current (13) to control the second current (12) for minimizing a DC-component of the first current (II).

Abstract: A switch circuit for battery-powered equipment, for example a mobile telephone or a portable computer, comprises a 4-terminal bi-directional semiconductor switch (M1) and a protection diode (Dbg). The switch (M1) has a control-gate terminal (g) for applying a control signal (Vg) to form a conduction channel (12) in a body region (11) of the switch, for turning the switch (M1) on and off between a battery (B) and a power line (2) of the equipment. The switch (M1) also has a back-gate terminal (b; bg) in a bias path that serves for applying a bias potential (Vmin) to the body region (11). The protection diode (Dbg) has a diode path in series with the back-gate terminal (b; bg) so as to provide in the bias path a rectifying barrier (25; 25′) that blocks current flow between the body region (11) and the gate-bias terminal (b, bg) in the event of a reverse voltage polarity across the switch (M1), for example when recharging the battery (B).

Abstract: Sigma-delta analog-to-digital converter topology with an error signal branch including a subtractor (10), a loop filter (4), and a quantizer (6), and a feedback branch including a digital-to-analog converter (8). The gain error caused by a return-to-zero switch in the feedback branch is cancelled by moving the return-to-zero switch (20) to the signal error branch.

Abstract: An amplifier circuit includes a driver stage made up of a differential pair and which is coupled to an output stage consisting of a first output transistor and a second output transistor having a common terminal coupled to the output signal terminal of the amplifier circuit. The driver stage provides class AB operation of the output transistors at a comparatively low supply voltage. In order to obtain such operation, a translinear network including the differential pair and a diode-connected transistor is coupled directly to a current mirror which includes the second output transistor. The translinear network and the current mirror dictate the setting of the first and the second output transistor, respectively.

Abstract: A current amplifier has an input terminal (1) for an input current (Iin) to be amplified in order to obtain a first output current (Iout1) at a first output terminal (2) via a first transistor (T1) and a second output current (Iout2) at a second output terminal (8) via a current mirror (6). A diode-connected transistor (T5) is coupled between the emitter of the first transistor and the input terminal of the current amplifier so as to improve the current branching at the input terminal, thereby extending the bandwidth and the output swing of the current amplifier.

Abstract: In a current mirror circuit (19) provided with a current mirror (29), an input (31) and an output (33) of which are coupled to an input (1) and an output (2), respectively, of the current mirror circuit (19), and a limiter circuit which having a reference current source (37) and a unilaterally conducting element (D1) having a transistor (T4), a source electrode of which is coupled to the input (1) of the current mirror circuit (19), a control electrode of this transistor (T4) is coupled to the reference current source (37), to a further output (35) of the current mirror (29) and to a reference voltage terminal (41) via a further unilaterally conducting element (D2), and a drain electrode of the transistor is coupled to a power supply terminal so that exclusively high-ohmic elements are connected to the further output (35) of the current mirror (29) at the instant when a current (I3) related to an input current (I1) of the current mirror (29) and flowing through the further output (35) of the current mirror (2

Abstract: In an amplifier arrangement, including a transadmittance circuit having an input coupled to an input of the amplifier arrangement, and a transimpedance amplifier having an input coupled to an output of the transadmittance circuit and an output coupled to an output of the amplifier arrangement, in which the transfer function modulus of the transimpedance amplifier has a first-order decrease above a first frequency F1 and a second-order decrease above a second frequency F2, which transimpedance amplifier is negatively fed back by means of a negative current feedback circuit, the negative current feed back circuit is constituted by a negative feedback impedance whose inverse of the transfer function modulus below the second frequency F2 is smaller than the transfer function modulus of the transimpedance amplifier and which transfer function modulus has a first-order increase above a third frequency F3 so that the transfer function modulus of the negatively fed back transimpedance amplifier has a first-order decr

Abstract: An amplifier circuit, for example, a class AB output stage, includes a series arrangment of a first transistor (T.sub.1) and a second transistor (T.sub.2), both arranged as diodes, a series arrangement of a third transistor (T.sub.3) and a fourth transistor (T.sub.4) and a series arrangement of a fifth transistor (T.sub.5) and an impedance (R). The first main electrode of the first transistor (T.sub.1) is coupled via the impedance (R) to the control electrode of the fourth transistor (T.sub.4). The first main electrodes of the second and fifth transistors (T.sub.2, T.sub.5) are coupled together and to the control electrode of the third transistor (T.sub.3). The control electrodes of the first, second and fifth transistors (T.sub.1, T.sub.2 and T.sub.5) are coupled together and to the second main electrodes of the first and the second transistor. This circuit provides a small quiescent current in the output transistors using relatively small input transistors (T.sub.1, T.sub.

Abstract: Errors occurring in the beam current measurement in a video output stage can be reduced by increasing the recharging rate of the capacitive load of a video amplifier, constituted by the picture display tube of a picture display arrangement, with the aid of a bias current or a quiescent current which is subtracted again from the current applied to an input of the beam current measuring circuit which is controlled by the video amplifier.

Abstract: The distortion of an emitter-follower output stage of a video amplifier for driving a cathode of a picture display tube can be reduced without rendering a beam current control via this output stage impossible, by using a low-distortion buffer stage for producing a negative feedback signal at the output of the output stage. A higher follow rate for small signal variations can be obtained with the aid of a bias current or quiescent current which then is subtracted again from the current applied to an input of a beam measuring circuit which is controlled by the output stage.