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公开(公告)号：AT150873T
公开(公告)日：1997-04-15
申请号：AT93911119
申请日：1993-05-06
Applicant: ANALOG DEVICES INC
Inventor： TSANG ROBERT W K , CORE THERESA A , SHERMAN STEVEN J , BROKAW A PAUL
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公开(公告)号：AU2978999A
公开(公告)日：1999-09-20
申请号：AU2978999
申请日：1999-03-03
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL
Abstract: An low dropout voltage regulator (LDO) drive reduction circuit detects when the LDO's output voltage is going out of regulation due to a falling input voltage while the output is lightly loaded, and reduces the drive to the pass transistor in response. This action prevents the LDO's ground current from rising unnecessarily. The drive reduction circuitry directly monitors the voltage across the pass transistor; when above a predetermined threshold voltage which is typically well-below the LDO's specified dropout voltage, the pass transistor drive is permitted to vary as necessary to maintain a specified output voltage. If the monitored voltage falls below the threshold voltage, indicating that the input voltage is falling and the output is lightly loaded, the drive reduction circuit reduces the drive current, which would otherwise get increased in an attempt to restore the output voltage. The transconductance of the novel drive reduction circuit is relatively high, making the region over which the drive reduction circuit is active small and permitting the threshold voltage to be precisely set.
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公开(公告)号：AT169401T
公开(公告)日：1998-08-15
申请号：AT94931437
申请日：1994-10-25
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL
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公开(公告)号：DE69807433D1
公开(公告)日：2002-10-02
申请号：DE69807433
申请日：1998-09-30
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL
Abstract: An inverter circuit, suitably implemented in the feedback loop of a series pass regulator, limits the maximum drive current through an output drive transistor connected to control the regulator's pass transistor. A first current source i1 biases an inverting amplifier that includes a transistor and an output resistor R, which inverts an input signal received from an emitter follower and feeds the inverted signal to an output drive transistor which has its collector connected to the base of the pass transistor. A second current source i2 is connected to allow the inverter's input signal to follow the emitter follower negative. When the follower is cut-off, i2 flows through the output resistor and increases the voltage of the signal fed to the output drive transistor by i2xR. The increased voltage establishes a maximum drive current based on i1, i2 and R, which is independent of the betas of the individual transistors.
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公开(公告)号：CA2134965A1
公开(公告)日：1993-11-11
申请号：CA2134965
申请日：1993-05-05
Applicant: ANALOG DEVICES INC
Inventor： DEVITO LAWRENCE M , BROKAW A PAUL
Abstract: 2134965 9322622 PCTABS00027 A monolithic interface circuit for use with a linear variable differential transformer (LVDT) position transducer. The interface circuit includes a drive circuit for providing an excitation signal of selectable frequency and amplitude to the LVDT primary winding. The interface circuit further includes a decoder responsive to signals induced in the LVDT secondary windings for computing the position p of the LVDT core as a solution to the equation p = K(A-B)/(A+B), where A and B represent the signals induced in the primary winding and K is a constant scale factor. The decoder includes circuitry for rectifying and filtering the secondary signals, a charge balance loop responsive to the detected signals for providing a binary signal having a duty cycle representative of B/(A+B), and an output circuit responsive to the binary signal for providing the position output. The decoder provides excellent scale factor stability and linearity and is relatively insensitive to variations in primary drive amplitude. In another embodiment, the decoder calculates the function K A/B using similar circuitry.
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Patent Agency Ranking
公开(公告)号：DE69807433T2
公开(公告)日：2003-01-09
申请号：DE69807433
申请日：1998-09-30
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL
Abstract: An inverter circuit, suitably implemented in the feedback loop of a series pass regulator, limits the maximum drive current through an output drive transistor connected to control the regulator's pass transistor. A first current source i1 biases an inverting amplifier that includes a transistor and an output resistor R, which inverts an input signal received from an emitter follower and feeds the inverted signal to an output drive transistor which has its collector connected to the base of the pass transistor. A second current source i2 is connected to allow the inverter's input signal to follow the emitter follower negative. When the follower is cut-off, i2 flows through the output resistor and increases the voltage of the signal fed to the output drive transistor by i2xR. The increased voltage establishes a maximum drive current based on i1, i2 and R, which is independent of the betas of the individual transistors.
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公开(公告)号：AU3099099A
公开(公告)日：1999-10-18
申请号：AU3099099
申请日：1999-03-18
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL
IPC: G05F3/30
Abstract: A high transconductance voltage reference cell produces a large change in output current for a very small change in input voltage near a settable equilibrium point, which can be made equal to two bandgap voltages, or to non-integer multiples of the bandgap voltage without the use of a resistive divider. A first and second pair of bipolar transistors, at least one of which have unequal emitter areas, are arranged in a crossed-quad configuration, with a first resistor interposed between one of the first pair and second pair transistors and a second resistor interposed between one of the second pairs' emitters and a common point. For input voltages below the equilibrium point, most of the current through the cell flows down one side of the quad. The voltage drop across the first resistor increases with input voltage, and causes the cell current to be abruptly switched from one side of the quad to the other at the equilibrium point. This large change in current induced by a small change in input voltage provides the cell's high transconductance. The cell can be made to exhibit a lower gm or some hysteresis by adjusting the relationship between the resistor values. The equilibrium point is dictated by the emitter area ratios between the quad's transistors, which cause the cell to carry a proportional-to-absolute-temperature (PTAT) current at the equilibrium point. The PTAT current can be made to compensate the quad to provide a temperature invariant equilibrium point.
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公开(公告)号：AU2220899A
公开(公告)日：1999-08-02
申请号：AU2220899
申请日：1999-01-11
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL , AUDY JONATHAN M
Abstract: A low voltage CTAT current source includes a bipolar transistor connected across two series-connected resistors. A voltage developed across the resistors turns on the transistor, making the current through the resistors CTAT. A second transistor supplies the resistor current; its base (if bipolar) is connected to the node between the resistors, which are selected to limit the transistor's base-collector forward bias and collector-emitter voltage to a preselected fraction of the first transistor's Vbe, allowing the CTAT current source to operate with supply voltages of less than two junction voltage drops. A PTAT current can be combined with the CTAT current to create a temperature-compensated current. A low voltage current mirror has the respective bases of a pair of cascoded transistors connected across a resistor which is also connected between the bottom transistor's collector and a programming current. When the transistors are matched, the top transistor's collector-emitter voltage about equals the voltage across the resistor, which is selected to establish a Vce just high enough to avoid saturation and allow the circuit to operate with only two unsaturating Vce's of headroom. The current mirror's lower headroom requirements are advantageously employed in a low voltage differential to single-ended converter circuit, and the current mirror and CTAT current source can be combined in numerous analog circuits to enable their operation at lower supply voltages.
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公开(公告)号：AU6050598A
公开(公告)日：1998-08-26
申请号：AU6050598
申请日：1998-01-28
Applicant: ANALOG DEVICES INC
Inventor： BROKAW A PAUL
Abstract: A temperature set point circuit employs a pair of bipolar transistors operated at unequal current densities, with the difference between the transistors' base-emitter voltages appearing across a trim resistor connecting their emitters. A pair of trim resistors, one of which may be external to an integrated circuit embodiment of the set point circuit, forms a resistor divider with the inter-base resistor and are selected to produce a desired temperature trip-point.
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公开(公告)号：DE69910741T2
公开(公告)日：2004-06-17
申请号：DE69910741
申请日：1999-02-16
Applicant: ANALOG DEVICES INC
Inventor： WALTER L , BROKAW A PAUL
Abstract: Apparatus for detecting a tooth of a body. The tooth has an edge terminating in a notch. The tooth and notch are disposed along an edge of the body. The apparatus includes a pair of Hall effect cells disposed adjacent to, and laterally disposed along, the edge of the body. A magnet is positioned to provide a magnetic field through the edge of the body and Hall effect cells. The magnitude of field passing through the Hall effect cells is related to the relative position between the tooth and Hall effect cells. The Hall effect cells produce an output voltage related to magnitude of magnetic field passing through the cell. A differencing circuit is fed by the pair of Hall effect cell produced voltages for producing a difference signal having a peak when the edge of the tooth is positioned between the pair of Hall effect cells. A peak detector detects the peak produced by the difference signal. A threshold circuit is fed by the differencing signal for producing a gating signal when magnitude of the difference signal exceeds a threshold level. The gating signal enables peak detector produced pulse to pass to an output of the apparatus and inhibits such detected peak from passing to the output in the absence of such gating signal. A threshold level adjusting circuit is responsive to the difference signal for tracking maxima in the difference signal and establishing the threshold level of the threshold circuit in accordance with the tracked difference signal maxima.
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