摘要:
A clamping circuit clamps a voltage received by an n-type semiconductor region without using a Schottky transistor. The clamping circuit includes a current mirror as well as first and second bipolar transistors. The current mirror receives a first current and supplies a second current in response. The first current is received by the first bipolar transistor, and the second current is received by the second bipolar transistor. The difference between the base-emitter junction voltages of the first and second bipolar transistors, in part, defines the voltage at which the n-type region is clamped. To start-up the circuit properly, current is withdrawn from the base/gate terminals of the transistors disposed in the current mirror. The circuit optionally includes a pair of cross-coupled transistors to reduce the output impedance and improve the power supply rejection ratio.
摘要:
The present invention comprises methods and circuits for spread spectrum frequency modulation that reduce peak spectral noise at the outputs or inputs of switching regulators. More specifically, the present invention modulates the operating frequency of the switching regulator in accordance with a frequency modulation waveform having a shape coordinated to a peak noise amplitude waveform that describes the correlation between the operating frequency of a switching regulator and the peak noise amplitude at the regulator's input or output absent spread spectrum frequency modulation.
摘要:
Bidirectional power conversion systems provide the ability to change power attributes to and from a component. Current bidirectional power conversion systems use a unidirectional power converter for each direction. The integration of the two normally independent power converters results in a bidirectional power converter with nearly half the size, weight, volume, cost and complexity. Described are embodiments of bidirectional power conversion systems that allow power transfer between two or more components without requiring the use of separate unidirectional power converters.
摘要:
A capacitor is provided including first and second electrodes formed from portions of the lead frame structure used in conventional integrated circuit packaging. The electrodes are encapsulated with dielectric molding material which provides dielectric insulation between the electrodes. A low power capacitively-coupled digital isolator circuit is also provided. The circuit employs a pair of the lead frame capacitors of the present invention and includes differential driver and receiver circuits. The receiver can also include an optional filter for increasing noise and glitch immunity.
摘要:
A three terminal control circuit for a low dropout voltage regulator having a PNP pass transistor is provided. The control circuit is capable of pulling the base-drive point down to a voltage of 3.0 volts or less to permit a current limiting resistor to be inserted between the base drive point and the base of the PNP pass transistor. The control circuit includes a pair of small-valued capacitors for providing stable operation with different output capacitors. The control circuit can also be used with p-channel FET pass transistors.
摘要:
An electrostatic discharge protection clamp particularly useful for with bipolar and biCMOS integrated circuits include an NPN transistor formed in an isolated tub in an epitaxial layer grown on a substrate. The collector of the NPN transistor is connected to the input terminal, and the emitter of the NPN transistor is connected to the substrate. A resistor interconnects the base and the emitter. Advantageously, the P-doped base can abut the P-doped isolation region forming the tub, and the P-doped isolation region can interconnect the emitter to the substrate. Below BV.sub.CES the clamp will look like an open circuit, and above BV.sub.CES the transistor will start conducting current. The transistor will break down collector to base. Conduction of the transistor causes a voltage drop across the base-emitter junction, and when this voltage drop exceeds the base-emitter forward voltage the transistor will turn on. Once the transistor is turned on and current starts flowing in the emitter, avalanche effects will cause the breakdown voltage to snap back to BV.sub.CEO and remain there until the emitter current drops below some low level, which will be at the end of the electrostatic discharge pulse. In the negative direction the tub to substrate diode provides an effective clamp which will clamp the voltage to a low value and limit the power dissipation in the junction. Alternatively, a bidirectional clamp can be provided in which a second NPN transistor is fabricated in the tub with the emitter of the second transistor connected to the input terminal and the collectors of the two transistors being interconnected by the N-doped epitaxial layer of the tub. The dopant conductivities can be reversed.
摘要:
A high thermal resistance bonding material for semiconductor chips includes a binder such as epoxy or polyimide and high thermal resistance material dispersed therein such as glass micropheres, glass beads, ceramic microspheres and ceramic beads. The particles of high thermal resistance material are sieved to obtain particles of generally uniform size. In plastic-encapsulated semiconductor chips, each chip is enveloped by the bonding material.
摘要:
A non-linear temperature correction circuit is provided which utilizes, in one embodiment, a pair of semiconductor elements such as a pair of transistors electrically connected to a common biasing current having a negative temperature coefficient and a negative temperature coefficient voltage is applied between the bases of the transistors. The output of one of the transistors is a non-linear output current which is non-linear with respect to temperature and where the output current has an inflection point.
摘要:
An improved infrared detector system includes a pair of thin film thermopile sensing elements that receives reflected energy from aspheric reflectors that are designed to provide optimum energy resolution. An absorbing coating can be placed above the sensors and extending beyond the periphery to improve the signal to noise ratio. A high gain low noise D.C. amplifier is coupled to the output of the infrared sensing elements while a high pass amplifier and low pass amplifier are designed to pass an amplified signal in the frequency range from approximately 0.2 Hz to 15 Hz. Finally, a combined peak detector and time dependent integrator summing amplifier circuit provides an enabling predetermined threshhold detection gate that requires either a predetermined large signal level or a multiple of small electrical signals within a preselected interval to produce an alarm enabling signal.
摘要:
A voltage regulator including a current regulator for maintaining predetermined currents in the voltage regulator is disclosed. The voltage regulator includes an output terminal for providing an output voltage; an adjustment terminal; and a control circuit connected to the output terminal at a level that differs from the voltage at the adjustment terminal by a predetermined voltage difference. The control circuit of the voltage regulator includes a resistive divider coupled between the output terminal and the adjustment terminal; a pair of transistors having their collectors connected in common and their bases respectively coupled to the resistive divider to provide a portion of the voltage difference between the output terminal and the adjustment terminal across their bases. The two transistors are adapted for operating at different current densities for providing a predetermined ratio in current flow through the pair of transistors when the voltage difference between the output terminal and the adjustment terminal is the predetermined voltage difference. The control circuit further includes a high-gain amplifier circuit connected to the emitters of the pair of transistors and to the output terminal for driving the output terminal to a maintained voltage level at which the current flow through the pair of transistors is at the predetermined current ratio and the voltage difference between the output terminal and the adjustment terminal is the predetermined voltage difference. The disclosed voltage regulator is useful as a negative voltage regulator.