Motorola Corporation

Dasym Technologies, Inc.

Other

William F Davis

Robert L Vyne

David M Susak

Stuart B Shacter

Marc T Stein

Robert N Dotson

Thomas M Frederiksen

Wilson D Pace

Richard T Ida

Howard G Shumway

A telephone caller screening device is operable with a pre-existing telephone line with an existing installed telephone device. In one mode, the telephone caller screening device selects and stores caller ID information from incoming telephone calls for later use to compare with caller entered identification data to determine whether the premise telephone user should be alerted to the incoming telephone call. In a second mode the telephone caller screening device controls the telephone system by generating an off-hook condition on the pre-existing telephone line to suppress the ring signal from an incoming telephone call to prevent audible ringing of the telephone device. The telephone caller screening device generates an alerting signal in an alerting device when the caller entered identification data compares with a stored caller identification data. In the event that the caller does not enter valid identification data, or the call recipient did not respond to the alerting signal in a predetermined time interval, the incoming telephone call is directed to a message device.

Telephone caller screening device

A telephone ring signal detector is coupled to a telecommunication line for detecting a first telephone ring signal, and for discriminating the first telephone ring signal from other line signals on the line. This detector comprises an event generator, coupled to the line, for receiving an incoming signal and for generating an initial event signal and an ending event signal, and a signal characteristic generator, coupled to the line and to the event generator, for generating a signal characteristic of the incoming signal after the initial event signal. This detector further comprises a signal characteristic limit device, for generating a predetermined signal characteristic range limit of the first telephone ring signal, and a signal characteristic comparator coupled to the signal characteristic generator, to the signal characteristic limit device and to the event generator, for comparing the signal characteristic with the predetermined signal characteristic range limit. A valid compare signal is generated when the signal characteristic is within the predetermined signal characteristic range limit. A ring detect signal is generated during the first quarter cycle time period of the first telephone ring signal in response to the valid compare signal and the ending event signal having occurred. The detector further comprises a line impedance device coupled to the signal characteristic comparator and to the line for activating an off-hook condition on the line during the first quarter cycle time period of the first telephone ring signal, in response to the ring detect signal.

Telephone ring signal detector

A telephone ring signal detector distinguishes a telephone ring signal voltage from a telephone pre-ring signal voltage on a telecommunication line at a premise, and is unresponsive to the pre-ring voltage and responsive only to the ring signal voltage for providing a telephone ring signal detect output signal during a first quarter cycle time period of a first telephone ring signal. A line switch couples an off-hook terminal impedance to the line in response to the ring detect signal for the purpose to exchanging telecommunication signals to and from the line. The detector provides a signal translating device for translating the ring and pre-ring signal voltages into a translated telephone signal having a translated peak ring signal voltage and a translated peak pre-ring signal voltage. During an adaptive voltage mode, an adaptive reference device responds to the translated telephone signal to provide an adaptive reference voltage which is adapted to be less than the translated peak ring signal voltage and greater than the translated peak pre-ring signal voltage when the off-hook impedance is uncoupled from the line. During a ring signal detect mode, a comparator provides the ring signal detect output signal when the translated telephone signal exceeds the adaptive reference voltage. The ring detect signal is independent of variations in a peak ring signal voltage, variations in a peak pre-ring signal voltage, variations in a pre-ring signal voltage transition time interval, variations in a telecommunication line resistance due to variations in a telecommunication line length, and independent of variations in a total ring signal impedance coupled to the line at the premise.

A telephone ring signal detector for detecting a telephone ring signal voltage on a telecommunications line connectable to at least one line telephone device. Detector includes a ring signal processor comprising a voltage translating device for providing a translated electrical parameter and an electrical parameter threshold setting device for providing a predetermined threshold reference electrical parameter value. The setting device provides a ring signal detect output signal when an electrical parameter value of the translated parameter exceeds the predetermined threshold reference electrical parameter value in a first quarter cycle time period of a first telephone ring signal cycle time period. In response to the ring signal detect output signal, a line impedance switch couples a first telephone device off-hook terminal impedance to the line to provide a first answering function, couples a detector line signal to the line and provides a simulated telephone ring signal to a telephone device output port connectable to an output telephone device. The output telephone device terminal impedance is monitored by an output line monitor to activate or deactivate a port coupling line switch which uncouples or couples the output port to the line in response to a second answering function by the output telephone device. The detector also receives and processes a caller line signal to activate an audible alerting signal. When in response to the alerting signal a person activates the line telephone device, an input line monitor uncouples the first off-hook terminal impedance from the line in response to a second telephone device off-hook terminal impedance associated with the telephone line device.

A method to extract at wafer probe the variation of lateral PNP basewidth of transistors formed in an integrated circuit which uses two lateral PNP devices having different and known basewidths before fabrication of the devices in the integrated circuit and then measuring the ratio of the saturation currents at wafer probe. The actual basewidth of the lateral PNP transistor is then related to the difference of the known basewidths of the two lateral PNP transistors and the ratio of the saturation measured currents thereof.

Method and structure for extracting lateral PNP transistor basewidth

An operational amplifier of the type which includes first and second differentially coupled input transistors which cooperate with a current mirror circuit also includes a first and second RTMM resistors which may be individually trimmed to reduce input offset voltage. Each RTMM resistor is coupled from the power supply rail through first and second diodes respectively to the first and second input terminals. In this manner, signals appearing on the input terminals which exceed the rail voltage will cause currents to flow through the RTMM resistors thus reducing their resistance, and reducing offset voltage.

Circuit utilizing resistors trimmed by metal migration

A differential amplifier in which the offset voltage is adjustable and which has a zero temperature coefficient after being adjusted. The differential amplifier includes a pair of differentially connected transistors, a current mirror circuit coupled to the collectors of the pair of transistors for providing differential to single current conversion and a current source for supplying a thermal current to the interconnected emitters of the pair of transistors. The magnitude of the thermal current is proportional to absolute temperature and inversely proportional to a resistance of a given resistivity. Trimmable resistive elements are provided for adjusting any offset voltage appearing between the base electrodes of the pair of transistors to substantially zero volts with the adjusted offset voltage being temperature independent.

Trimmable differential amplifier having a zero temperature coefficient

In an operational amplifier having an input stage of the type wherein first and second differentially coupled transistors cooperate with a current mirror circuit, an output transistor is provided having a compensation capacitor coupled between its collector and the input stage. The gain bandwidth product is enhanced by coupling a positive feedback device (e.g. a capacitor) between a collector of the output transistor and the collector of the first input transistor.

Amplifier having improved gain/bandwidth product

First and second resistors of a resistive network formed in a semiconductive substrate may be individually trimmed. The first and second resistive regions coupled at one end thereof have their other ends provided with metallic contacts. The resistive regions are disposed on the substrate such that current flowing from the first metallic contact to the second metallic contact through the first and second resistive regions causes the resistance of the first resistive region to be preferentially reduced. In contrast, current flowing from the second metallic contact to the first metallic contact through the first and second resistive regions causes the resistance of the second resistive region to be preferentially reduced. The resistive network is used in an operational amplifier circuit so as to permit the input offset voltage to be substantially reduced by selective trimming.

Operational amplifier utilizing resistors trimmed by metal migration

A quad operational amplifier integrated circuit is constructed such that each of the four cells forms a linear array. Devices which must be critically matched in each cell are symmetrically disposed with respect to the power devices of each cell about the same axis of symmetry. In this manner, critical devices will always reside on isothermal contours. To further enhance matching of critical devices, the axis of symmetry may be chosen to be colinear with stress axis of the semiconductor die in which the quad-operational amplifier implemented.

Symmetric layout for quad operational amplifier

A differential amplifier manufactured in integrated circuit form in a semiconductor substrate includes first and second differentially coupled input transistors. The emitters of the input transistors are coupled to a first source of supply voltage (e.g. V.sub.cc) and the collectors of the input transistors are coupled via load devices to a second source of supply voltage (e.g. ground). An RC gain reduction network is provided between the collectors of the input transistors and implemented in such a manner so as to provide substantially equal parasitic capacitances at the collectors of each of the input devices.

Differential amplifier including balanced two terminal series RC network

First and second resistors of a resistive network formed in a semiconductive substrate may be individually trimmed. The first and second resistive regions coupled at one end thereof have their other ends provided with metallic contacts. The resistive regions are disposed on the substrate such that current flowing from the first metallic contact to the second metallic contact through the first and second resistive regions causes the resistance of the first resistive region to be reduced. In contrast, current flowing from the second metallic contact to the first metallic contact through the first and second resistive regions causes the resistance of the second resistive region to be reduced.

Series resistive network

An amplifier includes an input stage having first and second differentially coupled transistors for receiving a differential input signal and providing a differential output to third and fourth differentially coupled transistors in the second stage. An RC circuit cooperates with the first and second stages to produce first and second additional pole-zero pairs, one occurring before the unity gain frequency and one occurring after the unity gain frequency. A second RC circuit cooperates with the second stage and introduces a third additional pole-zero pair which occurs below the unity gain frequency. As a result, the gain bandwidth product and the phase margin proximate the unity gain frequency are enhanced.

Amplifier having improved gain-bandwidth product

An improved operational amplifier circuit having an all NPN output stage includes a sense resistor in the output stage for developing a voltage thereacross proportional to any short circuit current flowing in the output stage. A diode clamp is coupled to the base of the emitter follower transistor which is in turn coupled between the input stage and the output stage for diverting base current from the base of the follower transistor when a sufficient voltage drop appears across the sense resistor.

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Tempe, AZ, United States of America

William F Davis