Abstract: The present invention is directed to a variable gain amplifier that may be used in RF telecommunication applications to obtain amplification of analog signals. It is also directed toward minimizing the effect that temperature variations have on the gain of the amplifier. A variable gain RF amplifier, according to this invention, has a differential amplifier and a gain control circuit. The gain control circuit has multiple transistors configured to affect a linear, variable resistor and to substantially distribute a uniform voltage potential across each transistor of the effective variable resistor.

Abstract: The low temperature-corrected constant voltage generator device includes a reference voltage generator, an amplifier connected between the reference voltage generator and an output terminal and a voltage divider connected to an input of the amplifier in order to supply a feedback voltage to the amplifier. The divider includes at least one first resistor in series with an element having, at least in the low temperature range, an impedance with a temperature dependence behavior different from that of the first resistor, to supply a lower feedback in the low temperature range.

Abstract: An operational amplifier trim circuit architecture that compensates for fabrication process and temperature drift mismatches reflected to the input as input offset voltage errors without additional temperature compensation circuitry. The operational amplifier includes a first input signal and second input signal applied to an input circuit stage. The input circuit stage amplifies the first input signal differentially with respect to the second input stage and generates a differential current which in turn is applied to a first current path and a second current path. The first current path and second current path have well-matched trim circuits. The first current trim applies a trim current to the first current path, and the second current trim applies a trim current to the second current path.

Abstract: A voltage to current conversion circuit is described. The circuit comprises a first differential amplifier for receiving an input voltage and producing an output voltage, and a second amplifier for converting the output voltage of the first amplifier to a current. The transfer function of the voltage to current conversion circuit is proportional to an exponential function that depends on the input voltage. The circuit is temperature and process independent. In a first preferred embodiment, the first amplifier comprises a first transistor for receiving an input voltage at its base terminal, a temperature dependent current source coupled to the emitter of the first transistor, and a positive voltage supply coupled to the collector through a diode coupled transistor, and a second transistor paired with the first transistor and having a base terminal coupled to an input voltage terminal, an emitter coupled to a temperature dependent current source, and a collector coupled to a voltage supply.

Abstract: A balanced input circuit which is used with an operational amplifier to obtain the difference between two input signals. In a temperature sensor application, one input signal is proportional to absolute temperature (PTAT) and one signal is complimentary to absolute temperature (CTAT) with the CTAT signal being the base-emitter voltage (Vbe) of a bipolar transistor. In this application the operational amplifier output is the PTAT signal minus Vbe times a scale factor determined by the feedback loop of the operational amplifier.

Abstract: Differential amplifiers include biasing circuits therein that can automatically account for process and/or temperature induced variations in &bgr; and thereby more uniformly maintain the voltage gain of the differential amplifier at a desired level. A differential amplifier is provided that comprises first and second bipolar transistors electrically coupled together as an emitter-coupled pair (ECP) and a biasing circuit that is electrically connected to first and second emitters of the first and second bipolar transistors, respectively. This biasing circuit includes a current mirror that sets a magnitude of an emitter bias current in the first emitter at a value proportional to (&bgr;+Z+1)/(&bgr;+1), where &bgr; is the gain of the first bipolar transistor and 1≦Z≦2. In this manner, the gain of the differential amplifier can be set at a level proportional to (&bgr;2+2&bgr;)/(&bgr;2+2&bgr;+1) which is a relatively weak function of &bgr;, even for small &bgr;.

Abstract: Disclosed is a compensation circuit for compensating a change in timing information of an input signal caused by thermal variations in a first circuit. The first circuit comprises one or more devices each having a temperature dependent on the input signal. Accordingly, the compensation circuit comprises one or more compensation devices each having a temperature dependent on the input signal. The compensation circuit is connected in series with the first circuit and the series connection receives the input signal and provides a timing-compensated output signal with substantially the same timing information as of the input signal. The thermal characteristic of at least one of the one or more compensation devices is proportional or in some other known relation to a corresponding one of the one or more devices of the first circuit. The compensation circuit provides a compensation output signal having substantially opposite or inverse thermal distortions than the first circuit.

Abstract: An amplifier output is biased to optimize performance characteristics such as gain and output voltage. A temperature-independent current is subtracted from a temperature-dependent current. The difference is injected at the amplifier output to bias the amplifier output such that performance characteristics are enhanced. An additional amplifier stage may be used to prevent the bandwidth performance of the amplifier from being affected by the current injection.

Abstract: In a gain variable amplifier apparatus, a thermal voltage proportional circuit converts a first control voltage into a second control voltage proportional to a thermal voltage, the gain of a gain variable amplifier being controlled by the second control voltage.

Abstract: An amplifier circuit is responsive to an input data signal which is substantially DC balanced. The amplifier circuit is operative to generate an amplified data signal, and includes: a limiting amplifier responsive to the input data signal and to an error correcting signal, the limiting amplifier being operative to generate the amplified data signal; a feed back circuit responsive to a signal proportional to the amplified data signal, the feed back circuit being operative to generate the error correcting signal. The feed back circuit includes: a low pass filter responsive to the signal proportional to the amplified data signal, and operative to generate a filtered signal; and an error amplifier responsive to the filtered signal, and operative to provide the error correcting signal to the limiting amplifier; whereby offset voltage caused by process characteristics of the limiting amplifier, and temperature variations in the limiting amplifier are canceled by the error correcting feedback signal.

Abstract: An offset voltage trimming circuit for sending a current from a constant-current source to a trimming resistor and thus obtaining an offset voltage, the offset voltage trimming circuit having a Zener diode with a temperature characteristic of zero, a transistor connected so as to form a diode and connected in series to the Zener diode, a current-mirror circuit connected to the transistor and a second resistor connected in series to the current-mirror circuit and having a temperature characteristic identical to that of the trimming resistor, with the current being supplied to the trimming resistor from the current-mirror circuit in order to prevent changes in the offset voltage due to changes in temperature.

Abstract: An apparatus and method for estimating an amplitude of a readback signal obtained from a data storage medium and input to a gain modifying amplifier involves sensing an amplifier output signal in response to a readback signal applied to the amplifier. An amplifier control signal is produced which is representative of a difference between the amplifier output signal and a reference signal. A compensation signal associated with a temperature coefficient of amplifier gain is generated, and an estimate signal indicative of the amplitude of the readback signal is produced using the compensation signal. The estimate signal is representative of readback signal amplitude when the estimate signal has a magnitude equivalent to that of the difference signal and a polarity opposite that of the difference signal.

Abstract: A signal amplifying circuit (24) includes level shifting input circuits (D1-D4) permitting input common-mode voltages (VIN1 and VIN2) of an amplifier and fault detection circuit (50) to vary between preset limits. The sense amplifier circuit (24) includes a DC offset buffer circuit (52) operable to receive an analog DC offset compensation signal and provide this signal to an input of the amplifier and fault detection circuit (50). The buffered DC offset compensation signal provided to the amplifier and fault detection circuit (50) is operable to reduce an aggregate DC offset voltage attributable to signal amplifying circuit (24) to a desired DC offset level. The amplifier and fault detection circuit (50) also includes a fault detection function whereby an output (VSENSE) of the amplifier circuit (50) is forced to a predetermined output state if either, or both, of the inputs (VIN1 and VIN2) of the sense amplifier circuit (24) are unconnected; i.e., floating.

Abstract: A circuit arrangement for amplifying a differential voltage signal in an output signal proportional to a voltage difference is provided, the voltages of a signal source that are to be compared being present at two inputs of the circuit arrangement, and a current signal proportional to the voltage difference being present at one output of the circuit arrangement, the circuit arrangement comprising cross-coupled transistors and the inputs being respectively connected to the base of one of the transistors, and a cross current of the circuit arrangement being present at the output. A compensation circuit is provided having a temperature behavior which corresponds to the temperature behavior of cross resistances of the circuit arrangement, the compensation circuit being associated with each of the inputs of the circuit arrangement.

Abstract: A variable gain amplifier (VGA) having a control voltage source that provides high gain-to-control voltage linearity over at least an 80 dB gain range. Further, the gain curve for the VGA is essentially independent of temperature. In the preferred embodiment, the VGA includes a two-stage bipolar differential amplifier. Each stage is a transconductor followed by current steering. The first stage amplifier is coupled to an exponentially varying current source to change the transconductance of the stage. The second stage amplifier is coupled to an fixed current source to maintain a fixed transconductance for the stage. To obtain exponential current steering, the control signal for the current steering circuitry is pre-distorted by the following equation:I/(1+exp(-f(V.sub.CTRL /V.sub.T))=I*A*exp(V.sub.CTRL /V.sub.REF),where A is a scaling factor, V.sub.T =kT/q, and T is temperature in Kelvin. The invention includes a fast, inexpensive control voltage source that provides such a signal.

Abstract: A communication unit (200) employs a method and apparatus for increasing an output impedance of a transmit amplifier during a receive mode of the communication unit. The communication unit includes a transmit amplifier, an antenna (209), and a signal receiver (211), and is operable in at least a transmit mode and a receive mode. During the transmit mode, the transmit amplifier, which includes an amplifying device (201), amplifies an input signal (221) and provides the amplified signal (233) to the antenna for transmission. During the receive mode, the antenna receives signals and provides the received signals to the signal receiver. To mitigate the transmit amplifier's effect on the received signals during the receive mode, the communication unit, during the receive mode, couples the transmit amplifier to the antenna and applies a bias (225) to the amplifying device to increase the output impedance (Z.sub.

Abstract: A precision GaAs low-voltage DC amplifier includes a level shift circuit, an amplifier and a first and a second bias control circuit. The level shift circuit shifts an input signal to generate a level shifted input signal, whose bias level is controlled by a first bias control voltage. The amplifier amplifies the level shifted input signal to generate an output signal. The bias level of the output signal is controlled by a second bias control voltage. The first bias control circuit insures that the first bias control voltage varies as necessary with temperature to hold constant the bias level of the level shifted input signal. The second bias control circuit insures that the second bias control voltage varies as necessary with temperature to hold constant the bias level of the output signal.

Abstract: A circuit for compensating a silicon strain gauge pressure transmitter. The circuit includes: a current source, an embodiment of which may include an amplifying device and means for supplying the current source with an electric potential, a strain gauge bridge, a plurality of resistances that includes a feedback resistance, a series resistance, a current sampling resistance, and a load with parameters. The key to this invention is to add a series resistance and a feedback resistance to the circuit which eliminates the need for R.sub.c, the current sample resistor, to be a thermistor, and increases the operating temperature range of the sensor by compensating the sensor's parameter variations with temperature.

Abstract: In a fully integrated logarithmic amplifier, an input current is fed via a diode, and in a reference current branch parallel thereto, a constant current flows through a similar diode. A voltage divider forms of the differential voltage between the two diodes a partial voltage on a variable resistor of the voltage divider, which is processed by a differential amplifier for forming the output signal. Parallel to the two current branches mentioned, there is provided an additional current branch having a constant current source and a diode. The differential voltage between the diode of the reference current branch and the diode in the additional current branch is also divided by a voltage divider. A differential amplifier forms of the voltage on the variable resistor of the voltage divider an error signal which changes the variable resistance from which the differential amplifier has formed the error signal as well as the resistance fo the variable resistor of which the output signal is formed.

Abstract: An auto gain controller having a temperature compensation function includes a transistor having a gate terminal, a drain terminal and a source terminal, and a gain amplifier with an inversion input terminal connected to the source terminal of the transistor, a non-inversion terminal for receiving a reference signal, and an output terminal connected to the gate terminal of the transistor, wherein a gain of the grain amplifier changes in proportion with a drain current of the transistor.

Abstract: A variable gain amplifier (VGA) may be useful in applications where the input amplitude is constant but the output must vary over a wide range. Some VGAs have a desirable exponential control characteristic, but an undesirable temperature characteristic that causes the gain to change with temperature when the control voltage is held constant with respect to temperature. The present invention is directed to a circuit that will convert a control signal (e.g., a voltage) that is constant with temperature into a voltage that can be applied to a VGA in such a way that the temperature variation of the VGA is eliminated without changing the desirable exponential control characteristics.

Abstract: A gain control signal (VCTRL) is provided to a temperature compensating circuit (12) which produces a differential temperature compensating gain control signal (VDT). A gain compensating circuit (14) receives the differential temperature compensating gain control signal (VDT) and provides a differential gain and temperature compensating gain control signal (VDTG) to an amplifier (16). The differential gain and temperature compensating gain control signal (VDTG) varies the gain of the amplifier (16) to be substantially linear with respect to variation of the gain control signal (VCTRL) and to compensate for variation in temperature.

Abstract: A circuit for stabilizing the gain-bandwidth product of analog circuits containing bipolar devices which determine the gm is disclosed. The stabilization circuit is formed to generate a reference current that is proportional to a reference capacitance C.sub.S and the thermal voltage V.sub.T. The reference current is ultimately mirrored (as the bias current) into the bipolar devices which determine the gm within the analog circuit. Since the transconductance gm of a bipolar device can be expressed as collector current, I.sub.C, divided by V.sub.T, the thermal voltage factor of the bias current itself will "cancel" the thermal voltage factor present in the transconductance. The effects related to the remaining variable, the capacitance, will be eliminated as long as the reference capacitance is formed to "track" the analog circuit capacitance by using similar types of capacitance to implement both capacitors and forming both the stabilization circuit and the analog circuit on the same silicon chip.

Abstract: An object of the present invention is to provide an AGC voltage correction circuit unaffected by a change in temperature.Since base-emitter voltages V.sub.BE of transistors Q9 and Q10 constituting a first reference current source 7 have temperature dependency, the variations of the gains of amplification transistors Q17 and Q18 dependent on temperature are diminished. Since transistors Q1 and Q2 constituting a second reference current source 2 have temperature dependency, a gain slope concerning amplification transistors Q17 and Q18 relative to temperature is corrected linearly.

Abstract: An impedance matching, reducing, or buffering circuit for permitting smooth signal flow from a first transmission medium to a second transmission medium. The circuit provides a first node adapted for coupling to the first transmission medium and for receiving a signal from the first transmission medium. The circuit further provides a buried channel transistor, that is coupled to the first node and that is biased by additional circuit devices, for transforming the impedance imposed on the signal. The use of the buried mode transistor reduces noise on the surface of the transistor while at the same time keeps other performance standards high. The circuit additionally provides a second node that is coupled to the buried channel transistor and that is adapted for coupling to the second transmission medium for conveying the signal to the second transmission medium.

Abstract: A residue amplifier includes input and output differential amplifiers. The output differential amplifier includes temperature-dependent current sources which compensate for temperature dependent gain variations within the input differential amplifier. Amplifier components are chosen to produce an overall gain equal to a ratio of fixed resistors, at a nominal temperature. The compensating current sources maintain this fixed gain value as the amplifier's operating temperature varies.

Abstract: A low-noise, low-power complementary metal-oxide-semiconductor (CMOS) integrated circuit common source differential amplifier is disclosed which is capable of amplifying low amplitude cardiac signals such as those produced by atrial depolarization of the heart. The amplifier has a pair of large area p-channel input field-effect transistors (FETs) biased in weak inversion. The amplifier also has active load FETs biased in the nonsaturation (linear) region by means of a varying gate terminal voltage applied by a dynamic bias circuit. The gate terminal voltage is varied to match the temperature dependence of the output conductance of the load FETs to the temperature dependence of the transconductance of the input FETs. The gate terminal voltage also sets a dc bias point which uses the nonlinearity in the load FET output conductance to cancel nonlinearity in the input FET transconductance.

Abstract: A temperature compensated logarithmic detector biased with a proportional to absolute temperature (PTAT) voltage produced in accordance with an area ratio of biasing transistors is disclosed. According to one implementation of the invention, the temperature compensated logarithmic detector includes biasing circuitry and a logarithmic detector cell. The biasing circuitry receives an input signal and produces a PTAT bias voltage from the input signal. The PTAT characteristic of the PTAT bias voltage is produced by an area ratio. The logarithmic detector cell converts the input signal to a logarithmic output signal in accordance with a logarithmic transfer function over a narrow range.

Abstract: A circuit arrangement having an input arranged to receive an input signal (U20) and an output for providing an output signal (U22). The circuit has an overall transfer function defined as the ratio between the output signal and the input signal and which is obtained by adding individual transfer functions of at least two different amplifiers with different slopes in their linear ranges and/or different limit values in their saturation ranges and/or different zero points alternately with positive and negative signs in a manner such that, at least partly, it corresponds substantially to a function of at least the third degree. This circuit arrangement generates, in a simple manner, an overall transfer function of at least the third degree, which can be used advantageously, for example, for the compensation of the temperature-verses-resonant-frequency characteristic function of a quartz crystal.

Abstract: A high speed integrated circuit operational amplifier chip having first, second, third and fourth successive edges includes a thermal centerline parallel to the second and fourth edges. An output driver circuit is located adjacent to an output bonding pad along the third edge and is disposed approximately symmetrically about the thermal centerline to provide approximately balanced differential heating of the operational amplifier chip relative to the thermal centerline. A low gain differential input circuit is located adjacent to the first edge and is disposed approximately symmetrically about the thermal centerline to provide approximately balanced responses of matched transistors in the low gain differential input circuit to isotherms produced by the differential heating.

Abstract: The invention relates to an amplifier stage comprising at least one module presenting a first transistor (T.sub.1) whose base forms an input terminal and a means to maintain a substantially constant current in the collector-emitter path of the first transistor (T.sub.1). Said means is comprised of a first current source (A.sub.1) connected to the collector of the transmitter (T.sub.1). A feed-back circuit has a direct voltage source (V.sub.3) arranged to maintain substantially constant the potential of the collector of the transistor (T.sub.1). It presents a path for the main current between a terminal (S'.sub.1) of the stage and the emitter of the transistor (T.sub.1). The value of said main current is a function of the voltage (V.sub.3) and of the potential (VCT.sub.2) of the collector of the transistor (T.sub.1); this potential remains substantially constant.

Abstract: An adjustable resistance device having a first parallel arrangement (1) of a first resistor and a first positive-feedback transconductor is provided with a control circuit (20) for controlling the controllable resistance section in the first parallel arrangement (1), which control circuit (20) includes a control loop including a second parallel arrangement (2) which is a copy of the first parallel arrangement (1). The control circuit (20) controls the controllable section of the second parallel arrangement (2) in such a manner that the negative resistance value formed by a second transconductor is substantially equal in magnitude to the resistance value of a second resistor, so that the second parallel arrangement (2) is bistable in the transition range.

Abstract: In an integrated circuit having first (VDD) and second (GND) power terminals, a differential amplifier has a load end connected to the first power terminal to produce-in response to an input signal (IN(1)-IN(2)) an output signal (OUT(1)-OUT(2)) when a common connected end of the amplifier is connected through an n-type constant current transistor (19) to the second power terminal. Connected between the power terminals, a bias resistor (25) and an n-type bias transistor (27) produces a bias circuit output voltage for comparison with a reference voltage (REF) by a voltage comparator (29) for producing a difference voltage which is delivered to a constant current transistor gate electrode and fed back to a bias transistor gate electrode to keep an amplitude of the output signal constant against a temperature variation. It is possible to use as the reference voltage a divided voltage of a source voltage supplied between the power terminals.

Abstract: A transmitting/receiving unit capable of setting the level of power for transmitting an output frequency signal, which correctly correspond to the level of a received frequency signal, without dependency upon change in the environmental temperature, the transmitting/receiving unit including a signal transmitting portion; and a signal receiving portion so as to be capable of generating an output signal, the level of which depends upon the level of a received signal, wherein the signal transmitting portion includes first variable-gain amplifying means having an amplified gain which is varied by first AGC voltage, the signal receiving portion includes second variable-gain amplifying means having an amplified gain which is varied by second AGC voltage, wave-detection means for generating DC voltage which is in proportion to level of an output signal from the second variable-gain amplifying means, and temperature-dependent-type automatic gain control voltage generating means for converting the DC voltage into AGC

Abstract: A cascaded amplifier is comprised of a number of amplifying stages connected in cascade such as the dual emitter-coupled amplifier shown. A first pair of transistors (14,20) provides limiting amplification and a second pair of transistors (16,18) with degeneration (22,24) provide linear amplification. Each pair of transistors is driven by a current source (28,26) which supplies a current (IT, IT2) proportional to absolute temperature (PTAT). The small signal amplification is then substantially independent of temperature and the value of the limited output is proportional to absolute temperature. This latter effect is countered by including a translinear variable current gain amplifier (54,56,58,60) in the last dual-gain stage of the cascaded amplifier to modify the output voltage in a manner inversely proportional to absolute temperature. A transfer function may thus be provided which is substantially independent of temperature.

Abstract: A level detecting circuit includes an operational amplifier, a first resistor, a first series circuit of second and third resistors, a fourth resistor, and a second series circuit of fifth and sixth resistors. The operational amplifier receives differential outputs from an AGC detecting circuit as inverting and non-inverting inputs. The first resistor is connected between one differential output of the AGC detecting circuit and the inverting input of the operational amplifier. The first series circuit is inserted in a negative feedback loop between an output of the operational amplifier and the inverting input of the operational amplifier. The fourth resistor is connected between the other differential output of the AGC detecting circuit and the non-inverting input of the operational amplifier. The second series circuit is connected between a bias voltage and the non-inverting input of the operational amplifier.

Abstract: An integrated circuit transconductor stage which suppresses the dependence on temperature and production process variables of a differential transconductor stage. A negative feedback relation is used, where the output of the transconductor stage is connected to an additional current generator (which is referenced to a precision external resistor), to a capacitor, and also to the gate of a PMOS transistor which sources current to a polarization stage, which in turn sources current to the transconductor stage, or to multiple transconductor stages.

Abstract: A circuit device for neutralizing thermal drift in a transconductor differential stage using a first circuit portion which corresponds structurally to the transconductor differential stage and has a pair of MOS input transistors defining a transconductance value which is substantially proportional to that of the transconductor differential stage, a pair of bipolar output transistors coupled to the MOS input transistors in a cascode configuration, and a second circuit portion being supplied a current from an output of the first differential portion to thereby output a current to be passed to the transconductor differential stage. The value of the output current is inversely proportional to temperature-dependent parameters of the transconductance.

Abstract: A composite amplifier includes a discrete active gain element with a feedback circuit that provides for low drift and low offset, but which also has low noise, short settling time and high bandwidth. This is accomplished in part by providing an attenuator in the feedback circuit and by providing a voltage source for the source of the discrete active gain element. The feedback circuit is connected between the gate and the source of the active gain element and is responsive to a change in voltage at the gate to supply a voltage of equal but opposite magnitude to the source. The source has an impedance whose Johnson noise is less than the noise of the active gain element. A differential amplifier in the feedback is constructed in multiple stages with a first stage having lower gain than a second stage.

Abstract: An output curvature correction is provided for a band-gap reference circuit that exhibits a temperature dependent output error in the form of k.sub.1 T - k.sub.2 Tln(k.sub.3 T) in the absence of the correction. A substantially constant collector current is driven through a correction transistor and used in connection with a proportional to absolute temperature (PTAT) transistor collector current in the uncorrected circuit. The difference between the base-emitter voltages for the two transistors has the form -k.sub.1 'T + k.sub.2 'ln(k.sub.3 'T.sub.). This voltage differential is scaled by an appropriate selection of resistor ratios and combined with the uncorrected circuit output to provide a corrected output that is substantially insensitive to temperature variations.

Abstract: An active filter circuit (10) that has a cut off frequency being substantially independent of absolute and temperature variations due to on chip resistors (R.sub.1, R.sub.2 and R.sub.3) has been provided. The active filter includes a transconductance gain amplifier (16) having first and second currents (I.sub.B and I.sub.E) the ratio of which are controlled such that the absolute and temperature effects of any on chip resistors of the active filter circuit are removed. The ratio of the first and second currents of the transconductance gain amplifier are controlled by a circuit that generates third and fourth currents (I.sub.b and I.sub.e) which are a function of a bandgap voltage. The circuit then utilizes the third and fourth currents and provides, to the transconductance gain amplifier, a current that is substantially equal to the ratio of square of the third current to the fourth current, and a current substantially equal to the fourth current.

Abstract: An op amp bias system that provides input offset voltage trim current with minimum offset thermal drift. The bias system includes a bias generator that provides bias current to the op amp and correction circuitry responsive to the bias current for providing an input offset trim current that compensates for offset drift error with changes in temperature.

Abstract: A temperature compensation control circuit to maintain a constant control gain in an AGC (automatic gain control) amplifier. The present invention compensates for the inherent temperature dependence without using any special processing or non-standard device structures. The present invention utilizes the voltage drop across n diodes in series to produce the control voltage difference (V.sub.C -V.sub.C *). These n series diodes are coupled to the collectors of a PNP emitter coupled pair with emitter resistance. This causes the control voltage difference to be dependent on temperature (nkT/q), but this dependency cancels out with the other inherent temperature dependency in the exponential function of the AGC amplifier which is also produced by a diode form. Thus, the present invention provides temperature compensation with minimum component matching problems and without the need for a PTAT (proportional to absolute temperature) current source.

Abstract: A band limiter connected between output lines of a differential amplifier. The band limiter includes a bipolar transistor connected to the output lines via capacitors, and includes a temperature detecting device for detecting ambient temperature. Transistor capacitance is connected to or disconnected from the output lines in response to a bandwidth limiting signal. The transistor constitutes a low-pass filter functioning as a band limiter when it is closed, whereas it functions as a variable capacitor which varies its capacitance in accordance with the ambient temperature when it is opened. The high-band frequency characteristic of the differential amplifier is temperature compensated by the transistor functioning as a variable capacitance.

Abstract: A receiver circuit includes a first amplifier for amplifying an input signal and for outputting a first amplified signal, a first bias circuit coupled to the first amplifier for supplying a first bias current to the first amplifier, where the first amplifier and the first bias circuit form a first circuit part, a second amplifier coupled to the first amplifier for amplifying the first amplified signal output from the first amplifier and for outputting a second amplified signal as an output signal of the receiver circuit, and a second bias circuit coupled to the second amplifier for supplying a second bias current to the second amplifier, where the second amplifier and the second bias circuit form a second circuit part, and the first and second bias circuits are independent of each other and have mutually opposite temperature characteristics so that the first and second bias currents respectively change in mutually opposite directions with increasing ambient temperature, to thereby suppress a change in current

Abstract: A circuit arrangement for measuring a mechanical deformation includes a pressure sensor with compression-deformable resistors for generating an analog deformation-dependent signal and a circuit for evaluating the analog deformation-dependent signal. The evaluating circuit includes a summing amplifier and a temperature-dependent coupling resistor connected between the input of the summing amplifier and the pressure sensor. The coupling resistor has a temperature coefficient adjusted to compensate for the temperature characteristic of the measuring sensitivity of the analog deformation-dependent signal. A temperature sensor generates a temperature-dependent signal corresponding to a static temperature characteristic of the evaluating circuit. There is provided a circuit for applying the temperature-dependent signal to the input of the summing amplifier to combine it with the analog deformation-dependent signal.

Abstract: A detector for use in an automatic gain control amplifier and operated to generate a gain control voltage in response to an amplitude of the output signal of an amplifier circuit includes five transistors connected in a detector circuit. The first transistor receives a bias voltage at its base and the second transistor receives a true signal of an input signal along with the bias voltage at its base. The third transistor receives a complementary signal of the input signal along with the bias voltage at its base. A first current source is connected in common to the emitters of the first to third transistors. A control voltage is supplied between the bases of the fourth and fifth transistors. A second current source supplies an operating current to the fourth and fifth transistors. A first load is connected in common to the collectors of the first and the fourth transistors. A second load is connected in common to the collectors of the second, third and fifth transistors.

Abstract: In accordance with the teachings of this invention, a novel wide-band, DC coupled, single-ended voltage-to-current converter and gain control circuit is provided. Of importance, the circuit of this invention is designed to receive an input signal referenced to ground such that for zero input current, zero output current is provided. A replica bias circuit is used which allows the output signal to be a function of the input signal without offsets introduced by bias currents used throughout the circuit.

Abstract: Electronic circuit arrangement in a temperature measurement circuit based on a platinum resistor (PT) as a temperature sensing resistor, whereby in addition to the platinum resistor there is provided a reference resistor (R1). The measurement circuit (S) is adapted to apply equally large DC currents (I5, I6) to both resistors having a common return lead (3) from these, and to sense the resulting voltage difference (U) across the resistors. By means of at least one operational amplifier (G) the voltage difference is adapted to cause an output DC current from the measurement circuit (S) being proportional to the voltage diffeerence and thereby constituting a measure of the temperature of the platinum resistor (PT). The measurement circuit (S) comprises means (L) for compensating for non-linearity of the temperature-resistance characteristic of the platinum resistor.

Abstract: A temperature independent, dynamically compressed, DC control voltage is obtained by converting by means of a converter circuit employing a current mirror, a linear variation of the voltage across a control potentiometer, external to the integrated circuit, in a logarithmic differential voltage between two output voltage terminals, respectively on a first and a second branch of the converter circuit, the voltage signal taken from the first branch of the converter circuit being fed to the input of a unitary gain stage biased by a current generator with a temperature coefficient corresponding to the reciprocal of the temperature coefficient of integrated resistances and the corresponding output signal of the unitary gain stage being fed to a first input of a differential stage, to the second input of which is fed the signal taken from the second branch of the converter circuit.