Differential pair amplifier with improved linearity in low-voltage applications
Granted: October 14, 1997
Patent Number:
5677646
A linear differential amplifier with improved voltage swing is disclosed. The linear differential amplifier corrects for an error voltage inherent in differential pair amplifiers, without hindering the available voltage swing, and thus, is particularly suited for low-voltage applications. The differential amplifier includes an input differential amplifier for receiving an input voltage difference to be amplified; a distortion correction differential amplifier for producing an error…
Temperature stabilized constant fraction voltage controlled current source
Granted: September 30, 1997
Patent Number:
5672961
A current source includes a control stage responsive to a stable, d.c. input voltage that is operative to produce a control voltage proportional to absolute temperature (PTAT), and an output stage responsive to the PTAT control voltage that is operative to produce an output current that is an essentially constant fraction of an output constant current source. The control stage includes a temperature-dependent control resistor of a given resistor type, and at least one control constant…
Methods and apparatus for disabling a watchdog function
Granted: July 15, 1997
Patent Number:
5649098
An apparatus for disabling a watchdog function of a watchdog circuit when a watchdog input pin of the watchdog circuit fails to receive an externally pulsed signal, which has a first predefined period. The watchdog circuit, while the watchdog function is enabled, generates a watchdog fault condition if the externally pulsed signal is not received at the watchdog input pin by the end of a predefined watchdog timeout period. The apparatus includes a pulse generation circuit for generating…
Communication interface circuit having network connection detection capability
Granted: July 15, 1997
Patent Number:
5649210
A method and apparatus for interfacing a computer system with another system is described including an interface circuit. The interface circuit detects if the voltage level on a signal line represents a valid logic level and if so, provides a valid signal in response. The valid signal allows the computer system to which the interface circuit is coupled to provide power to the interface circuit such that network communication may be established and the interface circuit can internally…
Methods and apparatus for improving temperature drift of references
Granted: May 13, 1997
Patent Number:
5629612
Methods and apparatus for improving the temperature drift of references by providing temperature compensation trimmable after packaging of the integrated circuit. In accordance with the method, first, second and third trim parameters are generated and trimmed at wafer sort so that the first parameter is substantially independent of temperature, and at a nominal temperature, the second and third parameters are zero, with the second being proportional to the temperature rise above nominal…
Bandgap voltage reference and method for providing same
Granted: April 8, 1997
Patent Number:
5619163
A bandgap voltage reference includes a series connection of a proportional-to-absolute-temperature (PTAT) voltage drop resistor with a V.sub.BE voltage drop transistor, such that a bandgap voltage V.sub.REF =V.sub.PTAT +V.sub.BE can be developed across the series connection. The bandgap voltage reference further includes a PTAT current generator having a pair of bipolar transistors which derive their base currents from a base current node between the PTAT voltage drop resistor and the…
Voltage overshoot limiter
Granted: April 1, 1997
Patent Number:
5617051
A voltage overshoot limiter having a detector circuit that looks at the node at which the undesirable overshoot would occur and provides a signal that is proportional to the unipolar rate of change of voltage at the node. This output is fed back to the first stage of the control circuit, error amplifier, etc. in such a manner as to reduce the rate of change of the circuit's nodal voltages to less than their slewing rates. By modifying the value of the detector's output for a given…
Reverse current prevention method and apparatus and reverse current guarded low dropout circuits
Granted: January 14, 1997
Patent Number:
5594381
A reverse current limited circuit configured to provide a reverse current limited low dropout voltage output. The reverse current limited circuit, coupled between a pair of terminals, comprises (i) a MOS pass transistor coupled in series between the first and second terminals, (ii) connection circuitry to connect the substrate of the MOS pass transistor to either one of the pair of terminals based on the relative magnitudes of the voltages measured on the pair of terminals, (iii)…
Simple high speed precision transconductance amplifier circuits
Granted: November 12, 1996
Patent Number:
5574403
A simple high speed precision transconductance amplifier circuit having a low offset. The circuit uses as an input stage two substantially identical transistors of a first conductivity type connected in series so as to have the same current there through, neglecting base currents. A second stage uses two substantially identical transistors of a second conductivity type connected in series, with the output of the amplifier being a current mirrored from the second stage. The offset is…
Method and apparatus for logic signal level translation to a semiconductor switch
Granted: October 15, 1996
Patent Number:
5565715
Method and apparatus for logic signal level translation to a semiconductor switch. The logic signal input is converted by a first circuit referenced to a first power supply level to a current source or sink gated on and off by the logic signal. The resulting current is coupled to the input of a second circuit referenced to a second power supply level to control complementary devices providing a switching signal for coupling to the semiconductor switch. The second circuit preferably…
Low power trim circuit and method
Granted: October 8, 1996
Patent Number:
5563549
A lower power trim circuit in accordance with the present invention includes the series connection of a resistive element, a first transistor, and a second transistor between nodes of a voltage source. The first transistor (which is coupled to the resistive element) is much larger, e.g. twice as large, as the second transistor. When the resistive element is in a low resistance state, the first transistor dominates a node between the first and second transistors due to its large size,…
High impedance common-emitter amplifier stage
Granted: September 3, 1996
Patent Number:
5552741
A high input impedance common-emitter amplifier stage is disclosed. This amplifier stage utilizes a transistor to buffer the base drive from the input stage of a Darlington circuit. This buffer action increases the input impedance of the common-emitter stage by a factor of beta (.beta.) of the buffering transistor. Various embodiments are disclosed.
Current protection method and apparatus and current protected low dropout voltage circuits
Granted: July 23, 1996
Patent Number:
5539603
A current limited low dropout voltage circuit for coupling between first and second power supply terminals and an output terminal for providing a current limited low dropout voltage output having a MOS pass transistor coupled in series between the first power supply terminal and the output terminal, a drive circuit coupled to the gate of the MOS pass transistor, circuitry for limiting the gate-source voltage of the MOS pass transistor to limit the maximum current therethrough to a first…
Method and apparatus for multiple output regulation in a step-down switching regulator
Granted: July 2, 1996
Patent Number:
5532577
A step-down switching regulator of the present invention includes (1) a magnetic storage device having at least one primary output and one secondary output, (2) a current sensing device for detecting current through a primary winding of the magnetic storage device, (3) a first switch, (4) a second switch, (5) a first comparator for detecting whether the current through the primary winding is greater than a limit value, (6) a second comparator for detecting loss of regulation in the…
Method and apparatus for increasing switching regulator light load efficiency
Granted: June 18, 1996
Patent Number:
5528132
A method and apparatus for increasing the light load efficiency of a DC-DC converter by reducing the quiescent power of the control section. In accordance with the invention, the DC-DC conversion is first started using a first regulator circuit to power the converter controller. When the converter output reaches an adequate level, the converter controller power input is switched to the output of the converter. At the same time, the first regulator circuit is turned off, whereby the…
Dual feature input/timing pin
Granted: April 16, 1996
Patent Number:
5508650
An apparatus for enabling an IC pin to function in a dual mode, which apparatus includes a first switch for coupling the IC pin to an input terminal when the IC pin operates in an input mode, and a charging circuit for sourcing current to the IC pin during a charging cycle of a timer mode. The inventive apparatus further includes a discharging circuit for sinking current from the IC pin during a discharging cycle of the timer mode. In one embodiment, the inventive apparatus further…
High side, current sense amplifier using a symmetric amplifier
Granted: March 12, 1996
Patent Number:
5498984
A self-contained, bi-polar high-side current sense amplifier which detects the magnitude and polarity of current flowing from one device to another, is disclosed. The amplifier has a symmetric architecture having two inputs and two outputs. One output is active for positive input signals corresponding to current flow in one direction, and the other output is active for negative input signals corresponding to current flow in an opposite direction. A symmetric current mirror in the…
Simple high speed precision transconductance amplifier circuits
Granted: August 29, 1995
Patent Number:
5446414
A simple high speed precision transconductance amplifier circuit having a low offset. The circuit uses as an input stage two substantially identical transistors of a first conductivity type connected in series so as to have the same current there through, neglecting base currents. A second stage uses two substantially identical transistors of a second conductivity type connected in series, with the output of the amplifier being a current mirrored from the second stage. The offset is…
High swing interface stage
Granted: May 9, 1995
Patent Number:
5414314
An integrated CMOS high swing interface output stage which can transmit and receive data from other devices which may include devices operating from a different, particularly a higher, voltage power supply. The interface utilizes three P-channel devices in a common well on the substrate and three N-channel devices in another common well on the substrate. Two of the three P-channel devices are connected in series between the positive power supply terminal and the output of the interface…
Precision transconductance amplifier
Granted: August 25, 1992
Patent Number:
5142242
A transconductance amplifier intended for high frequency, precision amplification. The amplifier has a unique architecture that sets gain by the ratio of two impedances. Unlike conventional amplifiers, the amplifier does not use external feedback. This makes the amplifier unusually stable since one needn't worry about phase shift due either to the amplifier or a feedback network. Consequently, the amplifier can be used in some rather unusual circuit applications, some of which would be…
