U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

North American Philips Corporation

U.S. Phillips Corporation

Franciscus A Schoofs

Aloysius J Nijman

Job F Van Mil

Adrianus W Ludikhuize

Martinus P Bierhoff

Albert H Slomp

Eise Carel Dijkmans

Nicolaas Lambert

Pieter Gerrit Blanken

David J Coe

Raymond J Grover

Dirk J Teuling

Johan Christiaan Halberstadt

David H Paxman

Armin F Wegener

Terence Doyle

Robert J Fronen

Frederik Van Dongen

James J McCormack

Paulus J Van Leest

A switch circuit for battery-powered equipment, for example a mobile telephone or a portable computer, comprises a 4-terminal bi-directional semiconductor switch (M ) and a protection diode (Dbg). The switch (M ) has a control-gate terminal (g) for applying a control signal (Vg) to form a conduction channel ( ) in a body region ( ) of the switch, for turning the switch (M ) on and off between a battery (B) and a power line ( ) of the equipment. The switch (M ) also has a back-gate terminal (b; bg) in a bias path that serves for applying a bias potential (Vmin) to the body region ( ). 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 ( &prime;) that blocks current flow between the body region ( ) and the gate-bias terminal (b, bg) in the event of a reverse voltage polarity across the switch (M ), for example when recharging the battery (B). Preferably the protection diode (Dbg) is integrated with a semiconductor device body ( ) of the switch (M ), with a p-n junction ( &prime;) or Schottky barrier ( ) forming its rectifying barrier in the bias path between the body region ( ) and the gate-bias terminal (bg).

Switch circuit and semiconductor switch, for battery-powered equipment

A power supply includes a transformer (TR) having a first winding (N1) for receiving an input signal (U.sub.i) and a second winding (N2) for supplying an output signal (U.sub.o). Switching means (SM) are coupled in series with the first winding (N1) for switching on and switching off a current through the first winding (N1). A parallel arrangement of a freewheel diode (D) and a field effect transistor (T) is coupled in series with the second winding (N2). The gate of the field effect transistor (T) is controlled from an amplifier (AMP). The amplifier (AMP) compares the drain-source voltage of the field effect transistor (T) with the voltage of a reference voltage source (RF1) and ensures that the drain-source voltage is equal to the voltage of the reference voltage source (RF1) as long as an adequate current flows in the second winding (N2).

Power supply having a synchronous rectifier circuit for improved

Picture display device comprising a plurality of electron transport ducts or transporting electrons in the form of electron currents, and selection electrodes for withdrawing each electron current at predetermined locations from its transport duct and for directing said current towards a luminescent screen. The selection electrodes are driven by a selection driver comprising integrated driver circuits having outputs which are DC-coupled to the selection electrodes and are cascaded as regards their power supply voltages in such a way that they apply both selection pulses and transport (bias) voltage to the selection electrodes.

Picture display and selection driver and integrated driver circuit for

A switched-mode power supply which uses the primary winding of the isolation transformer as the feedback mechanism for the regulation of the secondary voltage or current. The primary winding voltage and current are used to control the sampling of the primary winding to obtain a measurement signal which is proportional to the secondary voltage or current, and this measurement signal is used to control the switched drive signal. By using the primary winding as the feedback winding, parts can be saved, and the transformer can be of simpler construction.

Switched mode power supply with transformer and feedback via primary

A motor control arrangement including a control circuit for controlling the speed of an electric motor (EM), which control circuit comprises a measurement resistor (MR) and a switching transistor (ST) having a control electrode and a main current path coupled in series with the electric motor (EM) and the measurement resistor (MR), a pulse width control stage (PW) coupled to the control electrode of the switching transistor (ST), a motor current measurement stage (MI) for controlling the pulse width control stage (PW) in response to a motor current of the electric motor (EM), and a motor voltage measurement stage (MV) for controlling the pulse width control stage (PW) in response to a motor voltage (EM) of the electric motor (EM). In order to improve the speed control the motor current measurement stage (MI) comprises a voltage-current converter (M3, M4; A1) having an input coupled to a first terminal (3) coupled to the electric motor (EM) and having an output coupled to the pulse width control stage (PW), the voltage-current converter (M3, M4; A1) being adapted to realize a motor current transformation, and the motor voltage measurement stage (MV) comprises a resistor (R1) and a first current mirror (M1) having an input coupled, by a resistor (R1), to a second terminal coupled to the electric motor (EM) and having an output coupled to the pulse width control stage (PW).

Motor control arrangement, and shaver comprising such a motor control

A sawtooth oscillator includes a current source having an output coupled to a first capacitor for supplying it with a charge current (I). A discharge circuit discharges the first capacitor during a discharge period (TDS) in response to a voltage on the first capacitor. A second capacitor is coupled to the output of the current source. A switch interrupts the supply of charge current to the first capacitor during an interrupt period (TIS). Part of the charge current occurs during the discharge period (TDS). Subsequent to the interrupt period, the first capacitor receives a charge surplus built up by the charge current in the second capacitor. The current supply to the first capacitor is temporarily interrupted at least during a part of the discharge period. The second capacitor operates as an auxiliary capacitor in which a charge is stored which would otherwise have been supplied to the first capacitor. After the interrupt period the charge stored in the second capacitor is supplied back to the first capacitor. In this way substantially no charge current is lost during a total time period of a charge and discharge cycle. In the total time period the whole charge current of the current source ends up in the first capacitor so that tolerances in the discharge period do not affect the oscillation frequency of the sawtooth oscillator.

Sawtooth oscillator

It is possible to limit the voltage across a diode to the level of the pinch-off voltage of a JFET in an integrated circuit by connecting the diode in series with the JFET. As a result, the voltage offered through the JFET can be higher than the breakdown voltage of the diode, which is of particular importance in high-voltage ICs in which a highly doped buried zone is formed below the diode for reducing leakage currents to the substrate. According to the invention, the JFET together with at least one further circuit element is formed in a common island surrounded by an island insulation region. The gate of the JFET extends along the edge of the island and is separated from the relevant portion of the island insulation region substantially only by the source of the JFET. In the pinch-off condition, the gate divides the island into a high-voltage portion and a low-voltage portion which is coupled to the diode. The diode with the JFET occupies very little space and can be readily incorporated in integrated circuit designs.

Integrated semiconductor circuit having improved breakdown voltage

Charge pump including: a capacitor (4) which includes a first capacitor terminal (2) and a second capacitor terminal (8), a discharge switch (20) for discharging the capacitor (4) by the closing and opening of the discharge switch (20) in response to a first or second value respectively, of a clock signal (CS), a first current source (6) for supplying a first current (I1) to the first capacitor terminal (2), a comparator (12) whose first input (10) is connected to the first capacitor terminal (2) and whose second input (14) is connected to a reference voltage source (16) and which comparator generates a comparison signal (Vcomp) of which a first or second value denotes that the voltage (Vc) on the first input (10) is smaller or larger than the voltage on the second input (14), a current switch (24) passing a second current (I2) coming from the second current source (34) to an output terminal (28) once the clock signal (CS) has changed from the first to the second value, and prevents the second current (I2) flowing to the output terminal (28) once the comparison signal (Vcomp) has changed from the first to the second value. A sawtooth oscillator is formed by using the charge pump as a timing circuit with the oscillator providing the clock signal, and the second current from the output terminal being fed back to the first capacitor terminal.

Switched capacitor charge pump and sawtooth oscillator using same

A power transistor switching circuit includes a switching transistor. A switching signal triggers a control device which, via a delay device and a control amplifier applies a first control signal to a control electrode of the switching transistor. A thyristor is coupled to the control electrode of the switching transistor. The thyristor has a first trigger gate and a second trigger gate. A measuring circuit generates a measuring signal proportional to the current in the switching transistor. A comparison device compares the measuring signal with a reference signal for applying a second trigger signal to the thyristor second trigger gate. The control device includes a further control amplifier having an input coupled to the switching signal and an output which applies a further control signal to the first trigger gate. The delay device delays the first control signal with respect to the further control signal. When the switching transistor is turned on, the further control amplifier and the delay device prevent unwanted triggering of the thyristor due to the high impedance of the signal source which supplies the second trigger signal.

Power transistor switching circuit with controlled turn-off

A JFET configuration is obtained whose pinch-off voltage can be set by means of mask dimensions, without process changes, and which is at the same time suitable for operation at very low and very high voltages by cascoding of a first JFET with a diffused or implanted channel which is pinched off in lateral direction, parallel to the surface of the semiconductor body, with a second JFET with a high breakdown voltage and a higher pinch-off voltage than the first JFET. To increase the breakdown voltage still further, the combination of the first and second JFET may be further cascoded, without process changes, with a third JFET which has a channel of the conductivity type opposite to that of the first and second JFET.

Semiconductor device having series-connected junction field effect

It is usual in high-voltage integrated circuits to provide one or several breakdown-voltage-raising rings at the edge of a high-voltage island in the form of surface zones of the conductivity type opposite to that of the island. According to the invention, the function of these rings is locally taken over by one or several zones forming part of a circuit element and also provided with a breakdown-voltage-raising edge. Since the breakdown-voltage-raising zones are locally omitted alongside the island insulation, a major space saving can be achieved.

Semiconductor device having an improved breakdown voltage-raising

A comparator circuit comprising a comparator which includes a first and a second supply terminal for connection to a supply voltage. A first input terminal is connected to a reference voltage and a second input terminal is connected via an attenuation circuit to a signal terminal for connection to an input voltage. The attenuation circuit includes a resistor, a bias voltage terminal for connection to a bias voltage, and a MOS transistor having a gate (g), backgate (bg), source (s) and drain (d). The drain is connected to the signal terminal and the source and the backgate are connected to the second input terminal. The gate is connected to the bias voltage terminal and the resistor is inserted between the gate and the source of the transistor. In the case of high input voltages on the signal terminal, the MOS transistor operates in its saturation range and the voltage on the source continues to be substantially equal to the bias voltage. If the drain voltage falls below the bias voltage (Vbias), the MOS transistor is rendered conductive in the linear range and the voltage on the source follows the voltage on the drain. The comparator thus is protected against excess voltage on the second input terminal.

Comparator circuit comprising input signal attenuator

A semiconductor device and a circuit suitable for use in an intelligent power switch include an insulated gate field effect transistor (IGFET) (T2) and a power semiconductor switch (T1). The insulated gate field transistor IGFET (T2) is provided by a semiconductor body (6) which has a first region (7) of one conductivity type adjacent a given surface (6a) of the semiconductor body with the first region (7) forming at least part of a conductive path to a first main electrode of the power semiconductor switch. A second region (8) of the opposite conductivity type is provided within the first region adjacent the given surface (6a) and a third region (11) of the one conductivity type is provided adjacent the given surface (6a) within the second region (8), an area of the second region (8) underlying an insulated gate (14) provided on the given surface (6a) for defining a conduction channel (15) providing a gateable connection between the third region (11) and a fourth region (12) of the one conductivity type. The third and fourth regions (11 and 12) forming the source and drain regions of the IGFET and the second and third regions (8 and 11) together provide a zener diode, a conductive path being provided to the second region remote from the area underlying the insulated gate for reverse-biassing the zener diode. The IGFET may include a synchronous rectifier of a charge pump for providing a gate voltage signal to the power semiconductor switch which may be a power MOSFET (T2).

Semiconductor device and a circuit suitable for use in an intelligent

A semiconductor circuit has d.c. supply lines (10/13,11/14) and an excess voltage protection circuit. The protection circuit comprises a switching transistor (T1) connected in series with one of the supply lines (10/13) and a control circuit (15) which is responsive to a voltage detector circuit (16) coupled to the one supply line (10/13). The control circuit triggers the switching transistor to a non-conductive state upon detection of an excess voltage. The voltage detector circuit comprises a semiconductor element (T8) having a voltage breakdown characteristic correlated with one or more of the remaining semiconductor elements (T10). The semiconductor element (T8) is adapted to be driven to breakdown in response to a voltage across the supply lines less than that which will cause breakdown of the one or more remaining semiconductor elements T10. The increased current drawn by the semiconductor element (T8) at the onset of breakdown is effective to cause the control circuit to trigger the switching transistor to its non-conductive state.

Semiconductor circuit having an excess voltage protection circuit

A transient protection circuit for a d.c., voltage supply has a device such as a capacitor (C2) for absorbing transient energy developed on lines (11,12) of the supply. In order to provide such protection without loading the supply with a permanently connected large capacitor, the device for absorbing transient energy (C2) is indirectly connected in parallel with the supply lines (11,12) via a voltage responsive element (D1) which only conducts during the occurrence of a transient.

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Eindhoven, Netherlands

Franciscus A Schoofs