Abstract: A radio transceiver includes circuitry that enables received RF signals to be down-converted to baseband frequencies and baseband signals to be up-converted to RF signals prior to transmission without requiring conversion to an intermediate frequency. The circuitry includes a temperature sensing module that produces accurate voltage level readings that may be mapped into corresponding temperature values. A processor, among other actions, adjusts gain level settings based upon detected temperature values. One aspect of the present invention further includes repetitively inverting voltage signals across a pair of semiconductor devices being used as temperature sensors to remove a common mode signal to produce an actual temperature-voltage curve. In one embodiment of the invention, the circuitry further includes a pair of amplifiers to facilitate setting a slope of the voltage-temperature curve.

Abstract: A signal processing circuit includes a circuit stage for operating on signals in a signal path of an input signal, including main circuitry for operating on relatively small-value signals and alternative circuitry for amplifying/processing signals during a condition which otherwise would cause thermal imbalance in the main circuitry. The circuit stage includes switching circuitry for coupling signals in the signal path of the input signal to the main input circuitry during normal small-signal operating conditions and for coupling signals in the signal path of the input signal to the alternative circuitry during the condition which otherwise would cause thermal imbalance in the main circuitry.

Abstract: A waveform processing system, and associated methods and apparatus, may include a common mode feedback compensation circuit to adjust a voltage supplied to a differential circuit so as to substantially reduce or eliminate signal distortion associated with thermal tails. In an illustrative example, a feedback circuit may control a supply voltage to maintain a common mode voltage at the collectors of the input transistors of a differential amplifier. For example, the feedback may compensate for component tolerances and/or temperature changes that may cause the cause the input transistors to operate away from a nominal constant power operating point. In some embodiments, the differential circuit and common mode feedback compensation circuit may be configured to substantially reduce thermal tail effects by controlling the supply voltage to maintain a substantially constant power condition for the input transistors.

Abstract: In accordance with the present disclosure current sensing methods, apparatuses and arrangements are disclosed. The arrangement can include a sense element to convey a current from a source to a load and a compensation element can be located proximate to the sense element. The compensation element can have a resistance that changes proportional to a change in temperature of the sense element. The arrangement can further include an operational amplifier having a first input connected to the sense element, a second input connected to the compensation element and an output that provides an output signal that biases a current through the compensation element in response to a voltage across the sense element. The bias current can provide an output signal proportional to the conveyed current and the compensation element can provide temperature compensation for the output signal.

Abstract: A circuit and a method for nullifying temperature dependence of a circuit characteristic. The circuit includes a plurality of transistors configured such that they generate a gate voltage that includes a threshold voltage as a component. The gate voltage is applied to a transistor to generate a current that is proportional to a process transconductance parameter. The current is applied to a comparator having a differential pair of transistors, wherein each transistor has a process transconductance parameter. The circuit takes the ratios of the process transconductance parameter associated with the current to that of each transistor of the differential pair. By rationing the process transconductance parameters, temperature dependence is nullified or negated. The ratios can be used to set the hysteresis voltage of the comparator.

Abstract: A variable gain amplifier contains a plurality of differential transistor pairs. A temperature dependent current is generated in the current path of each differential transistor pair. A generated gain control current is converted to a temperature dependent gain control current and applied in circuit with control inputs of the transistors of the paired differential transistors. The temperature dependent gain control current is obtained from a gain control current corresponding to a desired gain which is then multiplying the control current by the temperature dependent current. The temperature dependent gain control current is modified to compensate for gain non-linearity by introducing an offset as a function of the gain control current.

Abstract: An amplifier includes a differential amplifier (10) having an input stage (20) for amplifying a differential input signal (Vin), and an output stage (6) coupled to the input stage (20) for producing and output signal (Vout). The input stage (20) includes main input circuitry (20A) for amplifying small-signal values of the input signal (Vin) and alternative input circuitry (20B) for amplifying the input signal (Vin) during conditions which cause thermal imbalance in the main input circuitry (20B). The input stage (20) includes switching circuitry (12) for coupling the input signal (Vin) to the main input circuitry (20A) during normal small-signal operating conditions and to the alternative input circuitry (20A) during large-signal operating conditions that cause thermal imbalance in the main input circuitry (20B).

Abstract: Attenuation cell comprising first and second differential pairs of bipolar transistors. A gain control device applies a voltage VA?VB between the bases of both differential pairs and comprises a set of three diodes in which a current IA, a current IB and the sum IA+IB of both preceding currents flow, respectively. The two diodes seeing current IB and IA+IB generate a voltage, respectively VB and VC, and the difference between these two voltages is used to generate a value Iz used in a control loop. A desired value Vct is transformed into information Ix, then into information Iy proportional to absolute temperature T, and an error amplifier uses information Iy?Iz and generates currents IA and IB by minimizing this difference.

Abstract: A fully differential current feedback amplifier suitable for using in a fully differential operational amplifier circuit is disclosed. Symmetrical low input impedance input circuits receive a differential input current and provide a set of four currents that correspond to the differential input currents. These current are input to a pair of subtraction circuits that output a first voltage signal responsive to the positive difference and a second voltage signal responsive to the negative difference. In some embodiments these signals may be further amplified. A common mode circuit is provided that averages the output voltage and feeds back current in response to the subtraction circuits. In this way the average common mode output DC voltage can be set to particular voltage levels.

Abstract: A circuit structure capable of adjusting gradient of output to temperature variation includes at least a sensing unit for detecting ambient temperature variation and generating a sensing signal, an amplifying unit connected to the sensing unit for increasing a level of the sensing signal, and an adjusting unit connected to the amplifying unit for increasing or decreasing an amplification ratio of the amplifying unit, so as to change a gradient of an output of the amplifying unit to temperature variation.

Abstract: A system for communicating information includes a variable gain amplifier (VGA) responsive to an input signal and a gain control signal for controlling a gain of the VGA. The system also includes a power amplifier responsive to the VGA. An output power level of the power amplifier is compared to a predetermined reference value to generate the gain control signal. The gain control signal is offset by a gain offset value. To change the output power level of the power amplifier from a first output power level to a second output power level, a first predetermined reference value and a first gain offset value associated with the first output power level are changed substantially concurrently to a second predetermined reference value and a second gain offset value, respectively, associated with the second output power level.

Abstract: A gain control circuit and a variable gain amplifier using the same. In the variable gain amplifier, gain control circuit generates a gain control voltage according to a control voltage, and a gain variable amplification unit is coupled to the gain control circuit and an input voltage to adjust an output signal output to a load according to the gain control voltage. In the gain control circuit, a level shifter with a constant current source generates a first voltage according to a control voltage. A first temperature compensation unit has a first temperature-controlled current source, and generates a second voltage according to a present operating temperature. A voltage conversion unit coupled to the level shifter and the first temperature compensation unit generates a gain control voltage according to the first and second voltages.

Abstract: A method of controlling noise in a pulse width modulation circuit includes varying a sample frequency and a range of information levels, wherein each sample within a data sample stream at the sample frequency represents a level within the range of information levels, to shift in frequency noise generated at the sample frequency during encoding of the data sample stream into pulse width modulated patterns.

Abstract: According to one example embodiment, a buffer, e.g., in a clock/signal distribution apparatus is provided that substantially reduces jitter due to power supply noise. Decoupler and input stage isolates load from the top rail power supply (VDD). In a more particular embodiment, jitter contributions from the bottom rail power supply (VSS) can be minimized by cross-coupled load devices within load. Substantial independence from process and temperature is facilitated through the use of current bias, such as Proportional to Absolute Temperature (PTAT) current bias.

Abstract: A method and circuit for trimming a current source packaged with a device can facilitate trimming of the current source without the need for additional pins or dual function pins, resulting in improved accuracy and/or simplified trimming techniques. An exemplary packaged device is configured with a trimming circuit comprising a current trimming network and a coupling circuit. An exemplary packaged device can comprise any op amp, current or voltage reference, and/or sensor device, and is configured with one or more monitor inputs. An exemplary current trimming network comprises a variable current source and a reference current source, wherein a magnitude of the variable current source can be compared to the magnitude of the reference current source. An exemplary coupling circuit is coupled between the current trimming network and the device and is configured for enabling and disabling connection of an output of the current trimming network and a monitor input of the device.

Abstract: A linear-in-decibel variable gain amplifier used for receiving an input voltage and generating an output voltage according to a first controlling voltage and a second controlling voltage. A voltage gain, that is, the ratio between the output voltage and the input voltage, has a denominator that is a pure exponential function, and the value of the pure exponential function is determined by the first controlling voltage and second controlling voltage.

Abstract: A linear decibel-scale variable gain amplifier includes an amplifying stage for generating an output voltage according to a differential input voltage, and a gain-controlling stage for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the linear decibel-scale variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage. The value of the voltage gain is unaffected by changes of the thermal voltage.

Abstract: A variable gain amplifier having a linear decibel-scale gain comprises an amplifying stage for generating an output voltage according to a differential input voltage, and a gain-controlling stage for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage.

Abstract: Disclosed is an RF transmitter circuit (10), as well as a method for operating the circuit. The RF transmitter circuit includes a VGA (20), that includes circuitry for generating a feedback signal, and a temperature compensation block (18) having an input coupled to a gain control signal and an output coupled to an input of the VGA for providing to the VGA a compensated gain control signal. The temperature compensation block further includes a bias input that receives the VGA feedback signal. The VGA feedback signal operates to modify the gain control signal to reduce an amount of variability in a VGA gain slope over a range of VGA output power.

Abstract: A resistance multiplier circuit coupled to a first node of a first circuit for providing a high-value resistance at the first node includes a first transistor, a second transistor being N times larger than the first transistor, and a resistor. In one embodiment, the first and second transistors are NPN bipolar transistors. The first transistor has its base and collector terminals coupled to the first node and an emitter terminal coupled to a second node. The second transistor has a base terminal coupled to the first node, a collector terminal coupled to a positive supply voltage, and an emitter terminal coupled to the second node. The resistor is coupled between the second node and a virtual ground node. When a voltage is applied to the first node, the resistance at the first node is (N+1) times the resistance of the resistor.

Abstract: Two amplifier transistors are arranged in parallel and a current source is connected to a common emitter line of the amplifier transistors and produces a temperature-independent quiescent current. In order for both the small-signal gain and the large-signal response to be independent of temperature, the emitters of the two amplifier transistors are connected to one another by a compensation resistor which has a negative temperature coefficient.

Abstract: Circuits and methods for a low voltage pre-distortion circuits that provide a temperature and logarithmically compensated voltage such that a gain change of a variable gain amplifier is linear in dB and has a reduced temperature dependency. A temperature compensation circuit multiplies the transfer function of gain of the amplifier versus gain control voltage by absolute temperature. A logarithmic compensation circuit removes the non-logarithmic factor of a “1” in the denominator of the transfer function.

Abstract: Low temperature coefficient input offset voltage trim with digital control for bipolar differential transistor amplifiers. The differential input pair of transistors are biased with a current proportional to absolute temperature. Trim current components are generated which also are proportional to absolute temperature and selectively coupled to at least one of the resistive loads to compensate for the original input offset. Control of the coupling of the trim current components preferably is by way of a control word written to and held in a control register. Use of an R-2R ladder using equal trim currents controllably coupled to the nodes of the ladder provide a binary progression in available trim currents. Other embodiments are also disclosed.

Abstract: A temperature compensated amplifier with variable gain and to a radio device having an amplifier according to it. The gain control and temperature compensation of a differential amplifier (210) are implemented by a control circuit (220), which has a balanced and differential output (V1, V2). The output voltage of the control circuit, or the control voltage, is arranged to be proportional to difference between two source currents (IGT1, IGT2), which difference can be varied on both sides of zero. The output of the control circuit is connected to the bases of the differential pair (Q1, Q2) of the variable gain amplifier, whereupon the ratio of the output current (iout) to the input current (iin) of the pair becomes dependent on the control voltage. This is arranged to be proportional to the absolute temperature, too. A temperature change then changes the control voltage the more the higher the control voltage is.

Abstract: A method and apparatus for compensating for offset and drift of offset in an amplifier circuit having metal oxide semiconductor transistors in an input stage thereof and including a node responsive to a bias to change the offset of the amplifier circuit. In one embodiment, an offset digital-to-analog converter provides a first programmable bias corresponding to an offset of the amplifier circuit. A drift digital-to-analog converter provides a second programmable bias corresponding to a drift of the offset of the amplifier circuit. The first programmable bias and the second programmable bias are combined and coupled to the node. In another embodiment, a first programmable offset/drift generator is provided, capable of sourcing a first bias to the amplifier node compensating for a first portion of the offset and a first portion of the drift of the offset of the amplifier circuit.

Abstract: A voltage reference is dynamically and digitally controlled by a digital function. The digital function may be implemented as a digital calculation or look up table. Inputs to the function include a modifiable trim value stored in a trim register, and a substrate temperature value. The preset value of the trim register is a trim preset value generated by cutting fuses and/or leaving fuses uncut. The cutting may be performed using laser trimming-devices. The output of the digital function is a corrected reference trim value that controls the gain of a voltage reference amplifier whose input is a band gap based voltage reference, and whose output is a derived voltage reference. The substrate temperature value is provided by a monolithic temperature monitor whose sensor may be on the same die as the derived voltage reference. The derived voltage reference provides a stable reference voltage that is dynamically and digitally controllable, to a host system that requires a voltage reference.

Abstract: A semiconductor device according to the present invention has a configuration that a resistance section is connected to only one of a current-mirror section forming a voltage conversion circuit and an output section. With this configuration, it is possible to determine the temperature dependency of an output voltage according to S factors of transistors forming one of the current-mirror section and the output section and a resistance value of the resistance section, and to suppress manufacturing irregularities caused by irregularities of the transistors between the two sections and those among a plurality of resistance materials.

Abstract: A temperature compensation circuit comprises a signal source to output a first signal corresponding to a temperature change of an ambient temperature to a predetermined temperature, and a multiplier to multiply an external gain control signal and the first signal and output a second signal proportional to the temperature change and the first signal to a variable gain amplifier to perform the temperature compensation with respect to the variable gain amplifier.

Abstract: A temperature compensated differential amplifier includes a first differential amplifier and a second differential amplifier. The first differential amplifier includes a feedback resistance, and has a gain proportional to temperature. The second differential amplifier is connected to the output side of the first differential amplifier, includes no feedback resistance, and has a gain inversely proportional to the temperature. The first differential amplifier carries out the temperature compensation of the gain and distortion of the second differential amplifier.

Abstract: A circuit arrangement prevents clipping of pulse metering (teletax) signals in a telephone line card channel that results from the differential impedance between a subscriber line interface circuit (SLIC) and the line at the frequency band of teletax signals. The circuit arrangement is configured to sense pulse metering signals through a delay circuit, which is coupled to a reflected signal cancellation circuit. The reflected signal cancellation circuit contains a transconductance amplifier circuit that generates a pair of complementary polarity output currents representative of the sensed teletax signal. One of these output currents is fed back to a programmed impedance element in the transmission channel path of the SLIC so as to effectively cancel the reflected teletax signal.

Abstract: A temperature compensated amplifier with variable gain and to a radio device having an amplifier according to it. The gain control and temperature compensation of a differential amplifier (210) are implemented by a control circuit (220), which has a balanced and differential output (V1, V2). The output voltage of the control circuit, or the control voltage, is arranged to be proportional to difference between two source currents (IGT1, IGT2), which difference can be varied on both sides of zero. The output of the control circuit is connected to the bases of the differential pair (Q1, Q2) of the variable gain amplifier, whereupon the ratio of the output current (iout) to the input current (iin) of the pair becomes dependent on the control voltage. This is arranged to be proportional to the absolute temperature, too. A temperature change then changes the control voltage the more the higher the control voltage is.

Abstract: A non-linear distortion compensation circuit and method automatically sets to an optimal value a phase shift of a variable phase shifter and an attenuation of an attenuator according to a transmission frequency, in a non-linear distortion extractor for extracting a non-linear distortion component generated during non-linear high-power amplification. A variable phase shifter shifts adjusts a phase of a signal determined by quadrature modulating the baseband signal. A high-power amplifier non-linearly high-power amplifies the quadrature-modulated signal. An attenuator attenuates the amplified signal by a gain equal to that of the high-power amplifier. A subtracter extracts non-linear distortion generated during the non-linear high-power amplification by subtracting the phase-shifted quadrature-modulated signal from an output of the attenuator. A control circuit automatically adjusts a phase shiftof the variable phase shifter and an attenuation of the attenuator according to a transmission frequency.

Abstract: A circuit and method for correcting thermal deviations of one or more output signals from an amplifier utilizes Early effect-compensated correcting signals to reduce the thermal deviations of the output signals. The correcting signals are derived from temperature-dependent signals, which correspond to the thermal deviations of the output signal. The temperature-dependent signals, however, include errors due to Early effect. The Early effect errors are compensated in the correcting signals by introducing reverse Early effect errors into the correcting signals. Consequently, the compensating signals can be used to more effectively correct the thermal deviations of the output signals.

Abstract: Two amplifier transistors are arranged in parallel and a current source is connected to a common emitter line of the amplifier transistors and produces a temperature-independent quiescent current. In order for both the small-signal gain and the large-signal response to be independent of temperature, the emitters of the two amplifier transistors are connected to one another by a compensation resistor which has a negative temperature coefficient.

Abstract: A differential amplifier of an exponentially-changing current producing circuit has a pair of transistors of which bases are connected to each other through a differential base resistor of a resistance value R, a control current of a value K2×T−(K1×K2×T×Vcont/K3) produced from a gain control current (K1·Vcont), a gain reference current (K3) and a bias current (K2·T) is fed to the base of one transistor, and an exponentially-changing current is output. Vcont denotes a gain control voltage, K1, K2 and K3 are constant, and T denotes an absolute temperature. An input signal is amplified in a variable gain cell at a gain corresponding to the exponentially-changing current, and an amplified signal is output. Therefore, the gain in the variable gain cell is controlled according to the exponentially-changing current.

Abstract: A differential amplifier is described comprising an input branch for receiving differential and common mode input signal components; an output branch providing differential and common mode output signal components; and the differential amplifier being adapted to set a relationship between the magnitude of the common mode output signal component level of the amplifier with respect to the magnitude of the common mode input signal component level to the input stage so that the common mode output signal component level intrinsically follows the common mode input signal component level as a common mode follower without using feedback control of the common mode output signal component. Also an asymmetrical amplifier is described which may be advantageously used as a component of the differential amplifier.

Abstract: Correction sensors and methods are provided for reduction of differential-heating signal errors along a differential signal path of an electronic circuit. An exemplary correction sensor includes first and second transistors which are coupled to different sides of the differential signal path and a differential error amplifier that couples a differential correction signal to the differential signal path in differential response to a differential error signal generated by like terminals of the first and second transistors. Bias generators are preferably included to bias at least one set of same terminals of the first and second transistors that differ from the like terminals.

Abstract: A temperature sensor has a first FET transistor circuit, whose operating point is located at the temperature-independent point, and a second FET transistor circuit whose operating point is above this point. The voltage difference in this case depends essentially linearly on the temperature. In addition, a circuit for controlling the gain of an amplifier circuit is provided, in which the current through the amplifier circuit at low temperatures is reduced by an appropriate control of the gate voltage of a transistor serving as a current source, so that an amplification which is substantially independent of temperature is carried out.

Abstract: A non-linear transconductance amplifier includes a differential input stage and a non-linear transconductance stage operatively coupled to the differential input stage. The differential input stage includes first and second inputs forming a non-inverting input and an inverting input, respectively, of the amplifier for receiving an input differential signal. The non-linear transconductance stage generates an output of the amplifier having a linear transconductance that is substantially zero when the input differential signal is within a predetermined range and a non-linear large transconductance when the input differential signal is outside the predetermined range. The amplifier provides improved response time to widely varying load conditions while possessing a low loop bandwidth. A threshold region where the output of the amplifier is substantially zero can be operatively adjusted and tightly controlled.

Abstract: An exemplary trimming circuit can be further simplified to include a single current source to provide for trimming of offset and temperature drift in a device, such as an op amp, voltage reference and the like. A single temperature-dependent current source is trimmed to a predetermined value, for example to zero, at a first temperature, and then the current from the temperature-dependent current source is used to trim output parameters, i.e., adjust the output variables, to a desired value at a second temperature. An exemplary trimming circuit comprises a temperature-dependent current source I(T), a current switch and a device to be, trimmed. The current switch is configured to suitably facilitate the trimming of the trimmed device through coupling of a fraction or multiple of the current signal from temperature-dependent current source I(T) to one or more offset-control terminals of the trimmed device.

Abstract: An Automatic Noise Reduction system wherein the Q of the frequency response is reduced using a negative output resistance to substantially eliminate the coil resistance of a speaker in a headset. The resulting system is less sensitive to variations in operating parameters, such as headset fit on a user and component variations. Temperature compensation of a negative output resistance amplifier is introduced to maintain stability over a wide range of operating temperatures. Temperature compensation includes substantially matching the temperature coefficient of the negative output resistance amplifier to the temperature coefficient of the speaker coil.

Abstract: A circuit for countering offset voltage in an amplifier induced by changes in the output load. The circuit comprises an input stage, an output stage, and first and second current compensation stages. The first current compensation stage is coupled to the output stage and produces a first compensation current that is a function of the output current. The input stage is coupled to the first current compensation stage from which it receives the first compensation current. The input stage is configured to cause a change in the voltage between its input terminals in response to the first compensation current. The second current compensation stage produces a second compensation current, which is also fed into the input stage to act jointly with the first compensation current. The first compensation current may be linearly related to the output current. The second compensation current may be exponentially related to the output current.

Abstract: A trimming circuit and method of trimming is provided for offset and temperature drift trimming of an op amp or voltage reference device, having an input stage, on at least two different temperatures. The trimming circuit has a current source stage, having first and second current sources which are trimmed at a first temperature, in a first step, to balance the currents of the first and second current sources. The two current sources are configured to be selectively connected, in a second step and at the first temperature, to the offset-control terminal(s) of the input stage and thereby to trim the output of the input stage. The first and second current sources also have different temperature coefficients and are interchangeable with other current sources to facilitate changing, in a third step, the temperature coefficient of one of the two current sources to facilitate offset trimming at a second temperature.

Abstract: A trimming circuit and method of trimming is provided for offset and temperature drift trimming of an op amp or voltage reference device, having an input stage, on at least two different temperatures. The trimming circuit has a current source stage, having first and second current sources which are trimmed at a first temperature, in a first step, to balance the currents of the first and second current sources. The two current sources are configured to be selectively connected, in a second step and at the first temperature, to the offset-control terminal(s) of the input stage and thereby to trim the output of the input stage. The first and second current sources also have different temperature coefficients and are interchangeable with other current sources to facilitate changing, in a third step, the temperature coefficient of one of the two current sources to facilitate offset trimming at a second temperature.

Abstract: An exemplary trimming circuit can be further simplified to include a single current source to provide for trimming of offset and temperature drift in a device, such as an op amp, voltage reference and the like. A single temperature-dependent current source is trimmed to a predetermined value, for example to zero, at a first temperature, and then the current from the temperature-dependent current source is used to trim output parameters, i.e., adjust the output variables, to a desired value at a second temperature. An exemplary trimming circuit comprises a temperature-dependent current source I(T), a current switch and a device to be trimmed. The current switch is configured to suitably facilitate the trimming of the trimmed device through coupling of a fraction or multiple of the current signal from temperature-dependent current source I(T) to one or more offset-control terminals of the trimmed device.

Abstract: A high frequency CMOS differential amplifier which comprises: a variable gain amplifier which amplifies differential input; a temperature sensing circuit; a gain-slope correction circuit which produces an intermediate control voltage as a function of temperature, thereby compensating for a change in slope of the gain control characteristics with temperature of the variable gain amplifier; a gain compensation circuit which is used to correct temperature/process variations of MOS transistors in high frequency differential amplifiers; and a bias control circuit.

Abstract: A variable offset amplifier circuit includes two differential transistor pairs and a variable current generator coupled to each differential pair to control tail current. Each differential transistor pair has a first transistor and a second transistor. The first transistors are for coupling to first and second loads. A current mirror and shunt is coupled to shunt a portion of current flowing through one of the first transistors from flowing through a correspondingly coupled load. The shunt current is mirrored from one of the second transistors to provide either positive current feedback or negative current feedback. The amplifier circuit has applications in a comparator circuit that also has a regenerative latch circuit, and as a sense amplifier in a receiver of a communications system.

Abstract: A differential amplifier is described comprising an input branch for receiving differential and common mode input signal components; an output branch providing differential and common mode output signal components; and the differential amplifier being adapted to set a relationship between the magnitude of the common mode output signal component level of the amplifier with respect to the magnitude of the common mode input signal component level to the input stage so that the common mode output signal component level intrinsically follows the common mode input signal component level as a common mode follower without using feedback control of the common mode output signal component. Also an asymmetrical amplifier is described which may be advantageously used as a component of the differential amplifier.

Abstract: A transconductor which has a transconductance gm and which receives an input voltage VIn and outputs in response to the input voltage Vin an output current Iout of gm×Vin, wherein: the transconductor includes a plurality of sub-transconductors which are connected in parallel to one another; and at least one control signal is input to the plurality of sub-transconductors, and the plurality of sub-transconductors are controlled by the at least one control signal such that at least one of the plurality of sub-transconductors has a negative transconductance, whereby the transconductance gm of the transconductor can be varied.

Abstract: A temperature compensation circuit comprises a signal source to output a first signal corresponding to a temperature change of an ambient temperature to a predetermined temperature, and a multiplier to multiply an external gain control signal and the first signal and output a second signal proportional to the temperature change and the first signal to a variable gain amplifier to perform the temperature compensation with respect to the variable gain amplifier.