Abstract: A voltage generator circuitry includes first to third bipolar transistors having commonly-connected base electrodes, first and second current mirror circuitries, first and second differential amplifiers; a first resistor; and a current-voltage conversion circuitry. The first current mirror circuitry supplies currents to the first to third bipolar transistors and to the current-voltage conversion circuitry. The second current mirror circuitry supplies currents to the first to third bipolar transistors, and s to the current-voltage conversion circuitry. The first and second differential amplifiers control the first and second current mirror. The current-voltage conversion circuitry converts a sum current of the first and second currents into an output voltage.

Abstract: A display apparatus displaying, a method for controlling the display apparatus, and an image providing apparatus. The display apparatus includes a communicator configured to receive image data of an image and brightness information of the image, a processor configured to generate a tone mapping curve by using the brightness information and to apply the tone mapping curve to the image data to provide tone mapped image data, and a display configured to display the image based on the tone-mapped image data.

Abstract: Disclosed is a digital pre-distortion device which includes a pre-compensation lookup table which outputs a first input value and a second input value adjacent to an input signal, a first distortion value corresponding to the first input value, and a second distortion value corresponding to the second input value; and a function generator which generates a pre-distortion function based on the first and second input values and the first and second distortion values and generates a pre-distortion value corresponding to the input signal from the pre-distortion function.

Abstract: Implementing a piecewise-polynomial-continuous function in a translinear circuit generally involves translinear elements that form translinear loops that are linked by a clamp transistor. A first translinear loop controls a first portion of the piecewise-polynomial-continuous function in a first area of operation. A second translinear loop controls a second portion of the piecewise-polynomial-continuous function in a second area of operation. When activated in the second area of operation, the clamp transistor draws current through one of the translinear elements without drawing current away from another translinear element of the translinear circuit.

Abstract: Implementing a piecewise-polynomial-continuous function in a translinear circuit generally involves translinear elements that form translinear loops that are linked by a clamp transistor. A first translinear loop controls a first portion of the piecewise-polynomial-continuous function in a first area of operation. A second translinear loop controls a second portion of the piecewise-polynomial-continuous function in a second area of operation. When activated in the second area of operation, the clamp transistor draws current through one of the translinear elements without drawing current away from another translinear element of the translinear circuit.

Abstract: A logarithmic amplifier produces a logarithmic output signal as a function of an input signal. The amplifier comprises a reference signal, first and second function generators, and a low-pass filter. The first function generator produces a periodic exponential waveform from the reference signal based upon a resistor-capacitor time constant, wherein the exponential waveform exponentially increases from a minimum to a maximum in each period. The second function generator produces a pulsed waveform from the exponential waveform, wherein the pulsed waveform comprises a first portion having a first amplitude for a first time period and a second portion having a different amplitude for the remainder of the signal period, and wherein the duration of the first time period is determined in response to the exponential waveform. The low pass filter produces the logarithmic output signal as a function of the pulsed waveform.

Abstract: Embodiments of the present invention provide systems, devices and methods for detecting the RMS value of a signal. The RMS detector uses multiple variable-gain stages and internal gain control to generate an RMS output signal based on an arbitrary signal input. This RMS detector significantly reduces the signal swings seen on a squarer within prior art RMS detectors and reduces the detector's dependency on DC offsets at low signal levels and overload errors at high signal levels. The embodiments of the present invention also improve the accuracy of the RMS detector within large dynamic signal ranges by obviating the operation of a squarer in saturation or out of the squaring region. Accordingly, embodiments of the present invention are able to more accurately detect RMS values on a signal, operate over relatively higher signal ranges, and better function within different signal modulation schemes, particularly those with large peak-to-average ratios.

Abstract: An embodiment of a logarithmic circuit may include a logging transistor, and a multi-tanh circuit arranged to provide temperature compensation to the logging transistor, where the multi-tanh circuit comprises a multiplicity of multi-tanh cells. In another embodiment, a logarithmic circuit may include a logging transistor, and a multi-tanh circuit arranged to provide temperature compensation to the logging transistor, where the multi-tanh circuit includes a first set of outputs arranged to provide an output signal and a second set of one or more outputs that are diverted.

Abstract: In one embodiment, a light dimming module is disclosed. The light dimming module has a dimming engine coupled to a digital input interface and an output interface. The dimming engine is configured to provide a N-segment piecewise linear exponential digital control signal, and the output interface is configured to control the intensity of a light source.

Abstract: An RF squarer circuit comprises a first RF multiplier and a first variable gain transimpedance amplifier (TIA). The first RF multiplier receives an RF input signal RFIN and provides a first output current. The first TIA receives the first output current as an input. The first TIA provides an output voltage VOUT.

Abstract: A square-function circuit includes an input field-effect transistor (FET) having a gate that is driven by an input voltage and is configured to conduct an output current. The circuit also includes a feedback circuit coupled to a source of the input FET, the feedback circuit being configured to drive a source of the input FET based on the output current to set a magnitude of the output current to be substantially equal to a square of the input voltage.

Abstract: Disclosed is a multiplier circuit including first and second squaring circuits comprising first and second differential MOS transistors respectively connected in cascode to first and second diode-connected MOS transistors. The first squaring circuit receives a differential sum voltage of a first input voltage and a second input voltage. The second squaring circuit receives a differential subtraction voltage of the first input voltage and the second input voltage. Outputs of the first and second squaring circuits are first and second terminal voltages of the first and second diode-connected MOS transistors. A differential voltage between the first and second terminal voltages corresponds to the product of the first and second input voltages.

Abstract: A circuit for generating a large RC time-constant includes an input node for receiving an input signal making a transition from a first state to a second state characterized by a first time-constant, and an output node for providing an output signal making a transiting from the first state to the second state in response to the input signal. The circuit also includes a first MOS field effect transistor coupled between the input node and the output node. The circuit further includes a first capacitor coupled between the output node and a ground node. A switch circuit is connected to a gate of the first MOS field effect transistor. The switch circuit is configured to bias the MOS field effect transistor to operate in saturation mode and the transition of the output signal is characterized by a time-constant associated with this large output resistance and the capacitor coupled to the output node.

Abstract: The present invention describes systems and methods to provide programmable analog classifiers. An exemplary embodiment of the present invention provides an analog classifier circuit comprising a bump circuit enabled to store a template vector, wherein the template vector can model a probability distribution with exponential behavior. Furthermore, the bump circuit is enabled to generate an output corresponding to a comparison between an input vector received by the bump circuit and the template vector stored by the bump circuit. Additionally, the analog classifier circuit includes a variable gain amplifier in communication with the bump circuit, and the variable gain amplifier can be adjusted to modify the variance of the template vector.

Abstract: Apparatus and methods for implementation of mathematical functions apparatus providing both speed and accuracy. Disclosed are specific circuits and methods of operation thereof that may be used for the purpose of implementing an exponential function, a squaring function, and a cubic function, using the same basic circuit. By applying a desired weighting function on a current source, an output current provides a value that corresponds exactly to the desired mathematical functions at discrete points, and closely tracks values in between the discrete points. The precision is defined by the selection of a voltage reference for the circuit. Various embodiments are disclosed, as well as embodiments implementing other exemplary functions.

Abstract: An anti-exponential amplifier produces an output signal that is an exponential/anti-logarithmic function of an input signal. The amplifier includes three function generators and a low-pass filter. The first function generator produces a periodic exponential waveform based upon a resistor-capacitor time constant, with the magnitude of the periodic exponential waveform exponentially increasing to a maximum value in each period. A second function generator produces a ramp waveform from the exponential waveform. The ramp waveform has a period and maximum amplitude substantially equal to those of the exponential signal. The third function generator produces a hybrid waveform with a first portion and a second portion, with the duration of the first period determined in response to the ramp waveform. A low pass filter produces the anti-logarithmic output signal as a function of the hybrid waveform. The resulting amplifier could be useful in a brightness or other parameter control for a display.

Abstract: The present invention relates to an exponential function generator which is realized with only CMOS element without BJT element, not limited by the physical properties of the element or a square circuit, and not complicated in its configuration, and a variable gain amplifier using the same. The exponential function generator includes a voltage-current converter, 1st to nth curve generators for mirroring the current from the voltage-current converter, outputting a current adjusted according to a predetermined ratio, and an output end for outputting the sum of the current from the 1st to nth curve generators. The exponential current generator is configured to generate the current exponentially adjusted according to the control voltage.

Abstract: An anti-exponential amplifier produces an output signal that is an exponential/anti-logarithmic function of an input signal. The amplifier includes three function generators and a low-pass filter. The first function generator produces a periodic exponential waveform based upon a resistor-capacitor time constant, with the magnitude of the periodic exponential waveform exponentially increasing to a maximum value in each period. A second function generator produces a ramp waveform from the exponential waveform. The ramp waveform has a period and maximum amplitude substantially equal to those of the exponential signal. The third function generator produces a hybrid waveform with a first portion and a second portion, with the duration of the first period determined in response to the ramp waveform. A low pass filter produces the anti-logarithmic output signal as a function of the hybrid waveform. The resulting amplifier could be useful in a brightness or other parameter control for a display.

Abstract: A transconductor including circuitry for automatically selecting a non-linear class A operation or a linear class AB operation based on an input signal to be processed to generate an output signal, and for automatically adjusting current from a power supply to a level needed for operation of the transconductor.

Abstract: Systems and methods are described for transmitting a waveform having a controllable attenuation and propagation velocity. An exemplary method comprises: generating an exponential waveform, the exponential waveform (a) being characterized by the equation Vin=De?ASD[x?vSDt], where D is a magnitude, Vin is a voltage, t is time, ASD is an attenuation coefficient, and vSD is a propagation velocity; and (b) being truncated at a maximum value. An exemplary apparatus comprises: an exponential waveform generator; an input recorder coupled to an output of the exponential waveform generator; a transmission line under test coupled to the output of the exponential waveform generator; an output recorder coupled to the transmission line under test; an additional transmission line coupled to the transmission line under test; and a termination impedance coupled to the additional transmission line and to a ground.

Abstract: A translinear network (34) has first (Q1, Q2, Q3, Q4) and second (Q4, Q3, Q5, Q6) translinear loops. A Trafton-Hastings clamp circuit (36) is connected to generate a piecewise-polynomial-continuous current IY, the value of which becomes undefined when current IX=0 due to a removable singularity in the transfer equation at this point. A current mirror (38) comprising a plurality of transistors (M1, M2, M3) is coupled to the Trafton-Hastings clamp circuit (36), and operates to add additional currents in transistors Q3 and Q5 to IX, when the Trafton-Hastings clamp transistor (Q7) conducts, so as to perturb the removable singularity in the transfer equation into the left half-plane.

Abstract: A squaring cell comprises a first circuit responsive to an input voltage to produce a corresponding current, and a second circuit, preferably in the form of an absolute modulator circuit, responsive to the current produced by the first circuit and to the input voltage to produce an output current that corresponds to the square of the input voltage. In one embodiment, the first circuit comprises an absolute value voltage-to-current converter; in another, the first circuit comprises a linear voltage-to-current converter. Techniques to improve accurate square law performance of the cell, independent of temperature, and of broad input voltage range and frequency, are presented.

Abstract: Provided is a CMOS exponential function generating circuit capable of compensating for the exponential function characteristic according to temperature variations. The exponential function generating circuit includes an voltage scaler scaling the value of an external gain control voltage signal, an exponential function generating unit generating exponential function current and voltage in response to a signal output from the voltage scaler, a reference voltage generator providing a reference voltage to the exponential function generating unit, and a temperature compensator compensating for the exponential function characteristic according to temperature variations.

Abstract: In a master block, the exponential conversion characteristic is determined on the basis of a common mode reference voltage and a reference voltage. In a slave block, the exponential conversion characteristic determined with the master block is used to create a control voltage and a gain control signal on the basis of a common mode reference voltage and a reference voltage. For example, a gain of the variable gain amplifier is controlled by using this gain control signal.

Abstract: The present invention discloses a circuit (10) adapted to compensate for RMR variations and shunt resistance across the RMR comprising a first current source (idc1) coupled to a first resistor (r1), a second current source (idc2) coupled to a second resistor (r2), wherein the first resistor (r1) and the second resistor (r2) are coupled, a resistive sensor (RMR) coupled on either side to a third resistor (r3) and to a fourth resistor (r4), and a transconductance feedback block (GM) coupled to the resistive sensor (RMR), the third resistor (r3), and to the fourth resistor (r4).

Abstract: An apparatus and method of generating a current pair Ip, Im where the ratio of the pair is exponentially related to a control signal, and where either Ip or Im is greater than or less than a minimum or maximum value includes a feedback correction circuit used to sense the value of Im or Ip. The correction circuit supplies a boost current Iboost when the sensed value of Ip or Im is less than or greater than the minimum or maximum value. Iboost is preferably maintained proportional to the difference of the desired value and Ip or Im.

Abstract: A first voltage conversion circuit converts first and second reference input voltages into first and second differential output voltage. A second voltage conversion circuit converts the first reference input voltage and a control input voltage into a third differential output voltage. The third differential output voltage is inputted to an exponential conversion element. The first and second differential output voltages are inputted to an active impedance bridge. The active impedance bridge outputs a gain control voltage of the first and second voltage conversion circuits. A balanced condition of the active impedance bridge determines the exponential conversion characteristic of the output current to the control input voltage of the exponential conversion element.

Abstract: Provided is a circuit to perform single-ended to differential conversion while providing common-mode voltage control. The circuit includes a converter to convert a single-ended signal to a differential signal and a stabilizing circuit adapted to receive the differential signal. The stabilizing circuit includes a sensor configured to sense a common-mode voltage level of the differential signal and a comparator having an output port coupled to the converter. The comparator is configured to compare the differential signal common-mode voltage level with a reference signal common-mode voltage level and produce an adjusting signal based upon the comparison. The adjusting signal is applied to the converter via the output port and is operative to adjust a subsequent common-mode voltage level of the differential signal.

Abstract: In a master block, the exponential conversion characteristic is determined on the basis of a common mode reference voltage and a reference voltage. In a slave block, the exponential conversion characteristic determined with the master block is used to create a control voltage and a gain control signal on the basis of a common mode reference voltage and a reference voltage. For example, a gain of the variable gain amplifier is controlled by using this gain control signal.

Abstract: In a master block, the exponential conversion characteristic is determined on the basis of a common mode reference voltage and a reference voltage. In a slave block, the exponential conversion characteristic determined with the master block is used to create a control voltage and a gain control signal on the basis of a common mode reference voltage and a reference voltage. For example, a gain of the variable gain amplifier is controlled by using this gain control signal.

Abstract: A precision analog exponentiation circuit includes a precision analog exponentiation circuit includes a first transistor coupled to a reference current for generating a voltage at the first transistor, a second transistor coupled to the first transistor for generating an output current, a variable current source coupled to the first transistor and the second transistor for generating a sum of the reference current and the output current in response to a feedback signal, and a feedback amplifier coupled to the first transistor for generating the feedback signal wherein the variable current source maintains the voltage at the first transistor substantially equal to a reference voltage so that the output current is substantially equal to an exponential function of a control voltage coupled to the first transistor and the second transistor.

Abstract: Methods and apparatus of amplifying signals. One method includes receiving a variable power supply, generating a variable bias current, and applying the bias current to a load such that an average output voltage is generated. The method further includes receiving an input signal, generating a current proportional to the input signal, and subtracting the current from the variable bias current. As the variable power supply changes value by a first amount, the variable bias current is varied such that the average output voltage varies by the first amount.

Abstract: A variable gain amplifier includes an input stage that receives an input signal and converts the input signal into a corresponding intermediate signal. An output stage provides an output signal based on the intermediate signal and a gain control signal, with feedback signal being provided to the input stage as a function of the gain control signal, so that the intermediate signal varies as a function of the input signal and the feedback signal. The linearity performance of the VGA is substantially constant at the output over the useful input range of signal amplitudes.

Abstract: Provided is a circuit to perform single-ended to differential conversion while providing common-mode voltage control. The circuit includes a converter to convert a single-ended signal to a differential signal and a stabilizing circuit adapted to receive the differential signal. The stabilizing circuit includes a sensor configured to sense a common-mode voltage level of the differential signal and a comparator having an output port coupled to the converter. The comparator is configured to compare the differential signal common-mode voltage level with a reference signal common-mode voltage level and produce an adjusting signal based upon the comparison. The adjusting signal is applied to the converter via the output port and is operative to adjust a subsequent common-mode voltage level of the differential signal.

Abstract: A switching mode N-order circuit comprises a first unit, a second unit and a comparator. The first unit includes an operational amplifier integral circuit to integrate a first voltage. The second unit has one or more stages of subunits in cascade each including an operational amplifier integral circuit to integrate a second voltage stage by stage. Each of the operational amplifier integral circuits is equipped with a switch to be controlled by the comparator to be discharged. The output of the N-order circuit is derived from the output of the second unit.

Abstract: A precision analog exponentiation circuit includes a precision analog exponentiation circuit includes a first transistor coupled to a reference current for generating a voltage at the first transistor, a second transistor coupled to the first transistor for generating an output current, a variable current source coupled to the first transistor and the second transistor for generating a sum of the reference current and the output current in response to a feedback signal, and a feedback amplifier coupled to the first transistor for generating the feedback signal wherein the variable current source maintains the voltage at the first transistor substantially equal to a reference voltage so that the output current is substantially equal to an exponential function of a control voltage coupled to the first transistor and the second transistor.

Abstract: Transconductance-based variable gain amplifiers amplify an input voltage by converting the voltage difference to a current and then amplifying the result. At least one resistor network is adjusted depending on the magnitude of the input voltage difference and the output desired. A network of MOS transistor switches with a small footprint adjusts the resistance of the input voltage circuit in a way to insure consistent resistance and low stray capacitance.

Abstract: In a master block, the exponential conversion characteristic is determined on the basis of a common mode reference voltage and a reference voltage. In a slave block, the exponential conversion characteristic determined with the master block is used to create a control voltage and a gain control signal on the basis of a common mode reference voltage and a reference voltage. For example, a gain of the variable gain amplifier is controlled by using this gain control signal.

Abstract: An RMS-to-DC converter implements the difference-of-squares function by utilizing two identical squaring cells operating in opposition to generate two signals. An error amplifier nulls the difference between the signals. When used in a measurement mode, one of the squaring cells receives the signal to be measured, and the output of the error amplifier, which provides a measure of the RMS value of the input signal, is connected to the input of the second squaring cell, thereby closing the feedback loop around the second squaring cell. When used in a control mode, a set-point signal is applied to the second squaring cell, and the output of the error amplifier is used to control a variable-gain device such as a power amplifier which provides the input to the first squaring cell, thereby closing the feedback loop around the first squaring cell.

Abstract: In a master block, the exponential conversion characteristic is determined on the basis of a common mode reference voltage and a reference voltage. In a slave block, the exponential conversion characteristic determined with the master block is used to create a control voltage and a gain control signal on the basis of a common mode reference voltage and a reference voltage. For example, a gain of the variable gain amplifier is controlled by using this gain control signal.

Abstract: A transfer function generator which generates an output that is a cubic function of the input for use in low voltage, high frequency applications. The cubic function generator creates a signal path through high speed npn devices, thereby allowing the use of high frequencies. Further, the topography of the cubic function generator requires a voltage drop across only two semiconductor devices, thereby allowing use of the circuit in low voltage applications.

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 power rising electronic device receives an input current and supplies an output current that is a function of a power of the input current having a relative whole-number exponent. The power rising electronic device includes a plurality of diodes equal to an absolute value of the relative whole-number exponent. The plurality of diodes are connected in series with one another to produce from the input current an input voltage that is a logarithmic function of a power of the input current. The electronic device further includes an output junction element, and a circuit for applying a voltage that is a function of the input voltage to the output junction element for producing a current that is an exponential function of the voltage applied thereto. The output current of the power rising electronic device is derived from the current produced in the output junction element.

Abstract: The present invention teaches parallel coupling what are herein termed a “switching stage” and a “steering stage,” thereby arranging the mixer and variable gain amplifier circuitry as a single merged circuit. The merged variable gain mixers of the present invention provide mixing and gain functionality utilizing only that power needed for a basic mixer function and only the transconductance of the basic mixer function (thereby eliminating non-linearities introduced by additional transconductance stages of prior art circuitry). Further, in the merged variable gain mixers described herein, no additional headroom is needed other than what is required by the basic mixer function. The present invention contemplates a variety of merged variable gain mixers including AC and DC coupled merged variable gain mixer of both single and double balanced configuration.

Abstract: An RMS-to-DC converter implements the difference-of-squares function by utilizing two identical squaring cells operating in opposition to generate two signals. An error amplifier nulls the difference between the signals. When used in a measurement mode, one of the squaring cells receives the signal to be measured, and the output of the error amplifier, which provides a measure of the RMS value of the input signal, is connected to the input of the second squaring cell, thereby closing the feedback loop around the second squaring cell. When used in a control mode, a set-point signal is applied to the second squaring cell, and the output of the error amplifier is used to control a variable-gain device such as a power amplifier which provides the input to the first squaring cell, thereby closing the feedback loop around the first squaring cell.

Abstract: A transfer function generator which generates an output that is a cubic function of the input for use in low voltage, high frequency applications. The cubic function generator creates a signal path through high speed npn devices, thereby allowing the use of high frequencies. Further, the topography of the cubic function generator requires a voltage drop across only two semiconductor devices, thereby allowing use of the circuit in low voltage applications.

Abstract: The input AGC and reference (REF) voltages are converted to currents and provided as differential inputs to a current amplifier. The current amplifier scales these currents proportional to absolute temperature. The translinear principle is used to realize the current amplifier and ensures linearity of the differential output currents. These currents are then converted to voltages by resistor elements. The result is applied to a simple differential pair that produces two AGC control currents that follow the hyperbolic tangent function. The two AGC control currents are equal when the AGC input is three-fourths the reference value. The overall gain response is well modeled by a second order function and is self-limiting at high gain values.

Abstract: A current steering circuit includes a first current steering pair of differentially coupled transconductance devices for current steering an input current signal to an output of the current steering circuit. A linearizer circuit includes a second pair of differentially coupled devices coupled electrically in parallel with the first current steering pair so that any current steering which takes place in the second pair is mirrored by the first pair. The linearizer circuit controls the second differential pair so that the current through the devices of the second differential pair that are coupled to the output device of the first current steering pair is exponentially dependent on the differential input voltage.

Abstract: An exponentiator circuit (24) is provided that includes a first transistor device, that includes a BJT (80) and a BJT (84) configured in a Darlington configuration, and a second transistor device that includes a BJT (88) and a BJT (92) also configured in a Darlington configuration. The first transistor device is coupled between a reference voltage and a summing node, while the second transistor device is coupled between an output node and a summing node. A programmable current iI is provided to the first transistor device and the second transistor device such that the base-to-emitter voltages of the two devices are provided at a different level. This results in the generation of a first current through the first transistor device and an output current through the second transistor device. An input current is provided at the summing node which is equivalent to the sum of the first current and the output current. The overall gain of the exponentiator circuit (24) is approximately exponential.

Abstract: An amplifier which outputs a nonlinear function in response to a linear input. The nonlinear response is a piece-wise linear approximation. The circuit includes an op amp which outputs a ramping voltage and a series of stages which change the scope of the ramping voltage. As the output of the op amp reaches a particular breakpoint, an additional stage of the circuit is activated so as to change the slope of the output. The new line segment has a new slope such that the combination of all these stages approximates a nonlinear response.