Abstract: A non-inverting amplifier includes an operational amplifier, an input resistor, and a feedback resistor. The operational amplifier amplifies and outputs a difference between an input voltage and a voltage of a control node. The input resistor is connected between a reference voltage port and the control node. The feedback resistor is connected to an output port of the operational amplifier and the control node. The non-inverting amplifier supplies a control current to the control node for controlling an offset voltage of the output port.

Abstract: An amplifier circuit includes an amplifier unit that amplifies a signal received by an input terminal and outputs the amplified signal to an output terminal, a feedback capacitor that is connected between the input terminal of the amplifier and the output terminal, and a controller that varies a capacitance in the feedback capacitor for a certain period when a potential of the output terminal in the amplifier unit becomes higher or lower than a certain potential.

Abstract: A method for tuning a transmitter in order to improve impedance matching to an antenna or to intermediate radio frequency stages uses an error detector that senses a deviation of the amplitude or phase angle of a load current of a power amplifier driver or of a power amplifier. A controller calculates a correction and dynamically adjusts tunable transmitter parameters, which may include values of components in matching networks or bias voltages in the power amplifier or the power amplifier driver, so as to reduce the deviation and thereby improve the impedance matching. The load current of the power amplifier may alternatively be sensed by measuring the duty cycle of its switching mode power supply. A transmitter having a power amplifier and one or more tunable circuit elements incorporates an error detector that senses the amplitude or phase of a load current and a controller that adjusts one or more tunable parameters to reduce impedance mismatch.

Abstract: Some embodiments regard a circuit comprising: a high voltage transistor providing a resistance; an amplifier configured to receive a current and to convert the current to a first voltage that is used in a loop creating the current; and an automatic level control circuit that, based on an AC amplitude of the first voltage, adjusts a second voltage at a gate of the high voltage transistor and thereby adjusts the resistance and the first voltage; wherein the automatic level control circuit is configured to adjust the first voltage toward the first reference voltage if the first voltage differs from a first reference voltage.

Abstract: A programmable system includes a programmable analog device including an operational amplifier to generate an output voltage based on input voltages at terminals of the operational amplifier. The programmable system also includes a system controller to direct the programmable analog device to reconfigure analog circuitry providing the input voltages to the operational amplifier. The reconfiguration of the analog circuitry allows the programmable analog device to implement discrete-time or continuous-time functions.

Abstract: Provided is an analog amplifier for amplifying an analog signal and an analog filter, and in particular, an apparatus and method for controlling gain and cutoff frequency of the variable gain amplifier and the variable cutoff frequency filter that is capable of changing the gain and cutoff frequency. The variable resister includes a plurality of resister segments in the variable resister and, when a plurality of resistance candidates for the variable resister are arranged in order of size, the resistance candidates form a geometric series.

Abstract: A line driver includes an output terminal set for outputting an output signal, a differential amplifier for amplifying an input signal, a series resistor set coupled between the differential amplifier and the output terminal set, a negative-feedback resistor set coupled to the differential amplifier, a feedback variable resistor set coupled between the differential amplifier and the output terminal set, and an adjusting unit coupled to the feedback variable resistor set. The adjusting unit is operable to adjust resistances of the feedback variable resistor set according to the output signal.

Abstract: A variable gain amplifier circuit includes: an operational amplifier having a non-inverting input terminal applied with a predetermined voltage; a feedback resistor having one end connected to an inverting input terminal of the operational amplifier and the other end connected to an output terminal of the operational amplifier; and a variable resistor having one end applied with an input voltage and the other end connected to the inverting input terminal of the operational amplifier.

Abstract: An integrated programmable gain amplifier circuit that receives at an input an analog signal, circuit including an operational amplifier and a gain setup network comprising resistive elements and selection elements, which may be controlled in order to setup the gain of the amplifier circuit. The gain setup network further includes capacitive elements, for defining, together with the resistive elements and the operational amplifier, an anti-aliasing filter of the active RC type.

Abstract: A circuit comprises an amplifier circuit and a trimming circuit. The amplifier circuit includes an operational amplifier. The operational amplifier has a first input configured to receive input signals, and the operational amplifier also has a second input and an amplifier output. One of the first input or the second input is a negative input. The trimming circuit is coupled to the amplifier output. The trimming circuit includes a termination resistor coupled in parallel with at least one trimming resistor. The termination resistor is coupled to a first switch in series, and the trimming resistor is coupled to a second switch in series. The amplifier output is connected back to the negative input through the first switch.

Abstract: There is provided an integrated circuit having a programmable gain amplifier and an embedded filter. The programmable gain amplifier and the filter comprise a gain element having an inverting input for receiving an input and a feedback signal, a non-inverting input coupled to ground, and an output. The gain element also has one or more feedback loops coupling the output of the gain element to the inverting input of the gain element. Each feedback loop has a switch coupled in series with at least one passive component. Each switch has a first state to connect the corresponding feedback loop and a second state to disconnect the corresponding feedback loop. Each switch is programmatically configurable to provide a first gain and a first bandwidth and a second gain and a second bandwidth such that the first bandwidth is substantially equal to the second bandwidth.

Abstract: Some embodiments regard a circuit comprising: a high voltage transistor providing a resistance; an amplifier configured to receive a current and to convert the current to a first voltage that is used in a loop creating the current; and an automatic level control circuit that, based on an AC amplitude of the first voltage, adjusts a second voltage at a gate of the high voltage transistor and thereby adjusts the resistance and the first voltage; wherein the automatic level control circuit is configured to adjust the first voltage toward the first reference voltage if the first voltage differs from a first reference voltage.

Abstract: An amplifier circuit includes an operational amplifier having first and second input nodes and one output node which is connected to a data line for which a pixel is provided; a feedback circuit having first and second elements which are connected to one of the first and second input nodes at their one ends; and a first switch section. The first switch section switches an operation mode between a first drive mode in which the other end of the first element is connected to the output node and a second drive mode in which the other end of the second element is connected to the output node.

Abstract: An audio power amplifier includes a pre-amplifier, an error amplifier, a comparator, a bridge circuit, and a feedback circuit, in which the gain of the pre-amplifier gradually increases when the audio power amplifier is powered on. The comparator generates a PWM signal by comparing a reference signal and an amplified audio signal. The bridge circuit has switches controlled according to the PWM signal such that a driving current alternately flows to and from a load. The feedback circuit generates the feedback signal indicating a condition of the load.

Abstract: An amplifier circuit for amplifying a differential input signal includes a first feedback resistance, a second feedback resistance, first transconductance circuitry, and second transconductance circuitry. The first feedback resistance is connected between a first input node and a first output node of the amplifier circuit. The second feedback resistance is connected between a second input node and a second output node of the amplifier circuit. The first transconductance circuitry is arranged to inject a transconductance current at a point along the first feedback resistance, and is configurable to vary the point along the first feedback resistance where the transconductance current is injected. The second transconductance circuitry is arranged to inject another transconductance current at a point along the second feedback resistance, and is configurable to vary the point along the second feedback resistance where the another transconductance current is injected.

Abstract: A feedback circuit disposed across input and output terminals of an amplifier is adapted so as not inject DC current back into the input terminal of the amplifier. The feedback circuit includes, in part, first and second current sources, a transistor, and a resistive load. The first current source supplies current to one of the terminals of the transistor in communication with an input terminal of the amplifier. The second current source receives this current and diverts it to a voltage supply. The transistor is maintained in the active region of operation. The resistive load has a first terminal in communication with an output terminal of the amplifier and a second terminal in communication with the transistor. The DC voltages at the two terminals of the resistive load are substantially equal so as to inhibit DC current flow therethrough.

Abstract: The present invention relates to a DC offset canceling circuit. In one aspect of the invention, a DC offset canceling circuit with independently configurable gain and roll-off frequency is provided. In one embodiment of the present invention, the DC offset canceling circuit is used in the receive path of a down-conversion wireless receiver. In another aspect of the invention, a method for independently varying the gain and the roll-off frequency of the DC offset canceling circuit is provided. In one embodiment, the method is used to independently operate a gain control scheme and a DC offset cancellation strategy in a DC canceling circuit.

Abstract: A self-configurable amplifier and method of amplification, including an RF signal level detector having an input connected to an RF signal, and an output configured to produce a control signal responsive to a power level of the RF signal. The control signal is supplied to a parametric adjustment circuit that includes an input connected to the control signal, and an output configured to provide a negative feedback responsive to the control signal. The negative feedback is supplied to an RF amplifier that includes an input forming an input of the self-configurable amplifier, an output forming an output of the self-configurable amplifier, and a control port connected to the output of the parametric adjustment circuit, such that one or more parameters of the RF amplifier is responsive to the negative feedback.

Abstract: An amplifier circuit for amplifying an input signal received at an input node of the amplifier circuit. The amplifier circuit comprises a feedback resistance connected between the input node of the amplifier circuit and an output node of the amplifier circuit. Transconductance circuitry is arranged to inject a transconductance current at a point along the feedback resistance. The transconductance circuitry is configurable to vary the point along the feedback resistance where the transconductance current is injected.

Abstract: An electronic volume circuit includes a first signal processing circuit and a second signal processing circuit that are cascaded together. The first signal processing circuit includes a first operational amplifier including an input terminal and an output terminal, one or more input resistors inputting one or more signals to the input terminal of the first operational amplifier, and a feedback resistor connected between the input terminal and the output terminal of the first operational amplifier. The second signal processing circuit includes a second operational amplifier including an input terminal and an output terminal, an input capacitor inputting a signal output from the first operational amplifier to the input terminal of the second operational amplifier, and a resistor and a capacitor connected in parallel between the input terminal and the output terminal of the second operational amplifier.

Abstract: Systems and methods to achieve an IC audio volume control requiring minimum silicon area and having an accurate volume control gain setting are disclosed. A resistive element in form of a R/2R ladder is deployed between an output node of an operational amplifier and an input node of the circuit. All resistors of said resistive element are unit resistors having a same resistance, wherein said unit resistors are arranged in parallel or series combinations to achieve a resistance desired. A first number of switches are deployed between nodes of the R/2R ladder and an inverting input of the operational amplifier. Furthermore a second number of switches are deployed between nodes within resistor units of the R/2R ladder and the inverting input. The circuit invented could have a single input or a differential input, or a single ended output or a differential output.

Abstract: A single-die multi-band switch includes a plurality of transmitter ports and a plurality of receiver ports, any one of which is selected to be connected to an antenna port. At least some of these switching topologies use a branched or cascaded switching system in order to reduce signal insertion loss. It is preferred that the individual switching elements be field effect transistors. The switching topologies employed include series-connected groups of transistors and interdigitated FETs.

Abstract: A variable resistor array adapted to make a resistance value between a first terminal and a second terminal variable, includes a plurality of resistors connected in series, first through nth MOS transistors selectively connected to the resistors, and first through nth switches having one input terminal connected to the source of the ith MOS transistor, another input terminal connected to a predetermined voltage, and an output terminal connected to a back gate of the ith MOS transistor, and connecting either one of the one input terminal and the other input terminal to the output terminal under control of the ith control signal. The ith switch connects the other input terminal to the output terminal, and the ith switch also connects the one input terminal to the output terminal.

Abstract: An amplifier for improving an electrostatic discharge (ESD) characteristic includes an operational amplifier, a first resistor circuit, a first fuse box, a second resistor circuit, and a second fuse box. The operational amplifier includes a first input terminal receiving a first input signal, a second input terminal receiving a second input signal, and an output terminal outputting an output signal. The first resistor circuit is connected between the second input terminal and a first node to prevent ESD from being input to the second input terminal. The first fuse box is connected between the first node and the output terminal of the operational amplifier. The second resistor circuit is connected between the second input terminal and a second node to prevent ESD from being input to the second input terminal. The second fuse box is connected between the second node and a terminal for receiving a ground voltage.

Abstract: A voltage-to-current converter is provided. The voltage-to-current converter comprises an amplifier, a resistor network, an R-2R network, and switches. The amplifier has a first input node (which is an input signal), a second input node, and an output node. The resistor network is coupled to the output node of the amplifier, includes a plurality of resistors coupled in series with on another, and includes a plurality of first tap nodes. The R-2R network is coupled to the resistor network and includes a plurality of second tap nodes. Additionally, at least one switch is coupled between the second input node of the amplifier and each first tap node, and at least one switch is coupled between the second input node of the amplifier and each of the second tap nodes.

Abstract: A feedback amplifier includes an operational amplifier having an input end and an output end. A first resistor is coupled with the input end of the operational amplifier. A second resistor has a first end coupled with the input end of the operational amplifier and a second end coupled with the output end of the amplifier. A voltage divider has a first end being operably coupled with the output end of the operational amplifier and a second end being analog grounded. In an embodiment, the feedback amplifier further includes a first switch coupled to the first end of the voltage divider and the output end of the operational amplifier, and a second switch coupled to an internal node of the voltage divider. In an embodiment, the feedback amplifier is configured to provide attenuation when the first switch is open and second switch is closed.

Abstract: A differential amplification circuit and a method corrects an offset voltage derived from a variance in resistances. With first and second input terminals brought to the same potential and set to a potential different from a reference potential, the resistance value of resistors is adjusted so that an output potential and the reference potential will be substantially equal to each other.

Abstract: A control circuit includes an operational amplifier having an inverting input, a non-inverting input, and an output, an array of impedance elements including capacitors are connected to the output of the operational amplifier, and a resistance switch crossbar array configured to store data in the form of high or low resistance states, wherein the resistance switch crossbar array is electrically connected between the array of impedance elements and the inverting input of the operational amplifier. The crossbar control circuit may be implemented in a control system to provide for adjustment of the control system to changes in environmental conditions or to change the function of the control system.

Abstract: A multiplying digital-to-analog converter includes an operational amplifier (OP-amp) operated under a first power supply voltage and a second power supply voltage; an OP-amp input switch block coupled to a common mode voltage for selectively coupling the common mode voltage to input nodes of the OP-amp, wherein all switches included in the OP-amp input switch block are implemented utilizing PMOS transistors only, and the common mode voltage is substantially equal to the first power supply voltage; a capacitor block coupled to the OP-amp input switch block; a sampling switch block coupled to the input signal for selectively coupling the input signal to the capacitor block; a reference voltage switch block coupled to the capacitor block for selectively coupling the reference signal to the capacitor block; and a feedback switch block coupled between the capacitor block and output nodes of the OP-amp.

Abstract: A receiver stage has an operational amplifier, a feedback resistor coupled between an output of the operational amplifier and an input of the operational amplifier, and a DC offset calibration circuit. The DC offset calibration circuit includes a plurality of resistors and a plurality of switches. Each resistor has a first end coupled to a supply voltage. First ends of each of the switches are coupled to second ends of each of the resistors, respectively, and second ends of the switches are coupled to the input of the operational amplifier.

Abstract: Programmable-gain amplifier systems are provided that are particularly suited for reducing degrading audio effects such as zipper noise. In one embodiment, these systems switchably couple an electronic potentiometer between an amplifier's inverting input terminal and interleaved tap points along a resistor that is coupled to the amplifier's output terminal. This arrangement introduces a number of fine gain steps between the gain steps that are realized with adjacent ones of the interleaved tap points to substantially reduce or eliminate zipper noise in a audio system that processes the system's output signal. The interleaved tap points facilitate efficient operation of the potentiometer during gain changes. They also permit the potentiometer to be effectively bypassed between gain changes so that distortion effects are substantially eliminated.

Abstract: A line driver includes an output terminal set for outputting an output signal, a differential amplifier for amplifying an input signal, a series resistor set coupled between the differential amplifier and the output terminal set, a negative-feedback resistor set coupled to the differential amplifier, a feedback variable resistor set coupled between the differential amplifier and the output terminal set, and an adjusting unit coupled to the feedback variable resistor set. The adjusting unit is operable to adjust resistances of the feedback variable resistor set according to the output signal.

Abstract: A physical quantity sensor includes a sensor element for converting a physical quantity applied from outside into an electric signal, a detection circuit for amplifying and detecting an output signal of the sensor element, and an adjusting circuit for adjusting the output signal from the detection circuit to a predetermined signal. The adjusting circuit has an amplifying circuit for amplifying the output signal from the detection circuit and a reference amplification circuit having an amplification ratio linked with the amplifying circuit. With this configuration, it is possible to change the amplification ratio of the amplifying circuit provided in the adjusting circuit in accordance with a power voltage. As a result, it is possible to realize a physical quantity sensor having stable sensor detection sensitivity and highly accurate ratiometric characteristic.

Abstract: A line driver includes: a differential amplifier for amplifying an input signal to generate an output signal; first and second series resistors coupled respectively to output terminals of the differential amplifier and through which the output signal is output; first and second negative-feedback resistors each coupled between a respective input terminal and a respective output terminal of the differential amplifier; first and second positive-feedback variable resistors each coupled between a respective input terminal of the differential amplifier and a respective one of the first and second series resistors; and an adjusting unit coupled to the first and second positive-feedback variable resistors to adjust a resistance thereof with reference to the output signal.

Abstract: A method and apparatus for selecting and mixing electronic signals. The circuit has an operational amplifier and two or more ganged, tapped-resistors in which the tap divides the resistance into a first and a second resistance. The tapped-resistors are connected so that either the first or the second resistance provides the effective input resistance for that signal at the operational amplifier. The second resistance of one of the tapped-resistors provides the output resistance for all signals at operational amplifier. As the tapped resistors are equivalent and their taps ganged, when the signals are mixed, those signals whose effective input resistance at the operational amplifier is selected to be the second resistance have unit gain, while those signals whose effective input resistance at the operational amplifier is selected to be the first resistance have a gain equal to the second resistance divide by the first resistance.

Abstract: Systems and methods are described for improving the startup linearization of a power amplifier. A bias network is provided to generate a bias signal during amplifier startup, and the amplifier is configured to produce an output signal in response to the input signal and the bias signal. A variable impedance is provided to couple the input signal and the output signal in parallel with the amplifier. A controller is configured to apply a weighting function to the variable impedance over at least a startup phase of the amplifier system. By applying a non-linear or other weighting function to the variable impedance during startup, the gain of the amplifier can be controlled to thereby extend a time period over which the output power of the amplifier increases in a generally linear manner toward an operating level.

Abstract: An automatic gain control circuit including a variable gain amplifier (11) adapted to receive a received signal (R) and to output an amplified signal (A) to an analog to digital converter (20), and a gain controller (12) which is connected to said variable gain amplifier (11) for receiving said amplified signal (A) and for controlling a gain of said variable gain amplifier (11). The gain controller (12) is adapted to determine an occurrence of a threshold event each time the amplified signal (A) has reached a predetermined threshold, decrease the gain of the variable gain amplifier (11) at each occurrence of a threshold event, measure a delay since the last threshold event, increase the gain of the variable gain amplifier (11) if the delay is greater than a delay specified value and if the gain of the variable gain amplifier (11) is not maximum.

Abstract: Provided is a switched-capacitor variable gain amplifier having high voltage gain linearity. According to the above amplifier, a sampling capacitor is shared and used at a sampling phase and an amplification phase, and thus a voltage gain error caused by capacitor mismatch can be reduced. Also, using a unit capacitor array enables circuit design and layout to be simplified. Further, in the amplifier, a voltage gain can be easily controlled to be more or less than 1, as necessary, and power consumption and kT/C noise can be reduced by a feedback factor that is relatively large, so that gain amplification performance can be improved.

Abstract: An amplifier is disclosed that includes configurable feedback based on the output of a received signal strength indicator. The feedback may be increased for high received signal levels, and decreased for low received signal levels. In an embodiment, the configurable impedance may comprise a plurality of discrete impedance settings. Amplitude and/or time hysteresis may be incorporated.

Abstract: One embodiment of the invention includes an amplifier system. The amplifier system comprises an amplifier stage configured to receive an input signal at an amplifier input and to provide an amplified output signal. The amplifier system also comprises a programmable input impedance stage comprising a plurality of transconductance stages. At least one of the plurality of transconductance stages can be selectively activated based on a selection signal, the at least one of the activated transconductance stages providing current through the amplifier input that adjusts an impedance associated with the amplifier input based on the amplified output signal.

Abstract: A linear programmable switch-capacitance gain amplifier (PGA) is described. The PGA divides the dB-gain curve into several parts by the concept of piece-wise linearity, and then simultaneously executes the dB-linear gain adjustment of MSB and the LSB at the same gain stage. Present invention achieves the PGA dB-linearity by setting up every capacitance of the sampling capacitor array and the holding capacitor array, then arranging the sampling capacitor array and the holding capacitor array by coordinating the switching of the capacitor switches.

Abstract: A gain controlled amplifier and a cascoded gain controlled amplifier based on the same are disclosed. The gain controlled amplifier includes an operational amplifier for amplifying an input signal, an input resistor connected to an input terminal of the operational amplifier, a feedback resistor connected to an output terminal of the operational amplifier, and a resistor circuit for providing voltages having different levels to the input terminal and the output terminal of the operational amplifier, respectively, according to a digital signal composed of specified bits. The gain controlled amplifier employs an R-2R ladder circuit controlled by a digital signal so as to obtain a gain that is in linear proportion to a decibel scale. Since the R-2R ladder circuit operates with a small resistance value, the chip size of the gain controlled amplifier can be reduced.

Abstract: A feedback-type variable gain amplifier including a first field effect transistor, a feedback circuit, and a load circuit. The first field effect transistor receives an input voltage signal through an input node, amplifies the input voltage signal, and outputs the amplified input voltage signal through an output node. The feedback circuit is coupled between the input node and the output node, and generates feedback impedance that is changed in response to a control signal. The load circuit is coupled between the output node and a voltage source, and generates load impedance that is changed in response to the control signal to cancel a change of input impedance due to a change of the feedback impedance. Therefore, since the input impedance is not changed when the gain of the amplifier is changed, a voltage standing wave ratio is good, and a range of gain control is broad.

Abstract: A programmable gain amplifier (PGA) circuit includes a gain adjust circuit and a gain select circuit that are both coupled to an output of an amplifier. The gain select circuit completes feedback to the amplifier while the gain adjust circuit is arranged to boost or cut the gain of the gain selection circuit. The gain adjust circuit can be arranged as a trim adjustment to the overall gain of the PGA circuit, where a different trim adjustment can be mapped to each gain setting such as from a look-up table. In other example implementations, the PGA circuit can periodically switch between multiple gain settings using a modulation scheme such that the overall gain is blended between the various gain settings according to a duty cycle, pulse-width, or delta-sigma modulation, with a time averaging effect on the overall gain of the PGA circuit.

Abstract: A variable gain amplifier circuit has an amplifier, a string of resistors, a plurality of gain switches, a current source, and at least two current switches. A first input terminal of the amplifier receives an input voltage signal. The string of resistors are coupled between an output terminal of the amplifier and a bias voltage input terminal. Each of the gain switches is coupled between a second input terminal of the amplifier and one of connection nodes between two of the resistors. Each of the current switches is coupled between the current source and one of the connection nodes. The current source provides a current through the turned-on current switch.

Abstract: In accordance with a particular embodiment of the present invention, an apparatus is offered that includes a configurable feedback low noise amplifier (LNA) connected to a common source connected input transistor to realize a specific value of an input impedance, the input impedance being controlled by transconductance, the overall gain being defined by a global current feedback network. In more specific embodiments, the LNA is used to provide a wide frequency band and a defined input impedance. In other embodiments, the LNA achieves a low noise parameter and low output distortion. Also, the LNA can use a ladder network of grounded switches and floating resistors in order to avoid floating switches in a feedback path. The LNA can increase parametric yield. The LNA can be used to control noise, gain, distortion, and input impedance independently.

Abstract: Systems and methods are described for improving the startup linearization of a power amplifier. A bias network is provided to generate a bias signal during amplifier startup, and the amplifier is configured to produce an output signal in response to the input signal and the bias signal. A variable impedance is provided to couple the input signal and the output signal in parallel with the amplifier. A controller is configured to apply a weighting function to the variable impedance over at least a startup phase of the amplifier system. By applying a non-linear or other weighting function to the variable impedance during startup, the gain of the amplifier can be controlled to thereby extend a time period over which the output power of the amplifier increases in a generally linear manner toward an operating level.

Abstract: A voltage-to-current converter is provided. The voltage-to-current converter comprises an amplifier, a resistor network, an R-2R network, and switches. The amplifier has a first input node (which is an input signal), a second input node, and an output node. The resistor network is coupled to the output node of the amplifier, includes a plurality of resistors coupled in series with on another, and includes a plurality of first tap nodes. The R-2R network is coupled to the resistor network and includes a plurality of second tap nodes. Additionally, at least one switch is coupled between the second input node of the amplifier and each first tap node, and at least one switch is coupled between the second input node of the amplifier and each of the second tap nodes.

Abstract: An amplifier for improving an electrostatic discharge (ESD) characteristic includes an operational amplifier, a first resistor circuit, a first fuse box, a second resistor circuit, and a second fuse box. The operational amplifier includes a first input terminal receiving a first input signal, a second input terminal receiving a second input signal, and an output terminal outputting an output signal. The first resistor circuit is connected between the second input terminal and a first node to prevent ESD from being input to the second input terminal. The first fuse box is connected between the first node and the output terminal of the operational amplifier. The second resistor circuit is connected between the second input terminal and a second node to prevent ESD from being input to the second input terminal. The second fuse box is connected between the second node and a terminal for receiving a ground voltage.

Abstract: In a single-ended or differential instrument amplifier, an input offset may be adjusted by driving current into the impedance of a feedback network of the amplifier. The amplifier may be provided with programmable gain capability. The impedance does not change with different gain settings, such that the input offset adjustment is equal for all gains. The amplifier may receive the output of a sensor such as, for example, a gas detector such as a thermal conductivity detector. The gas detector may be utilized to measure a gas flowing from a gas source such as, for example, a chromatographic column.