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Solutions Search - Low Bias Current Amplifiers (Ib < 100pA)

LTC2063 Micropower Precision Oxygen Sensor

Jul 27th 2017
This low power precision gas sensor circuit operates in an oxygen level range of 0% to 30%, with a nominal output of 1V in normal atmospheric oxygen concentrations (20.9%) when the gas sensor has been fully initialized. Total active power consumption is less than 2.1μA on a single rail supply. Since ...

Circuit LTspice 

 

LTC2063 RTD Sensor with ±1°C Precision

Jul 27th 2017
This low power platinum resistance temperature detector (RTD) sensor circuit draws only 35μA total supply current on a minimum 2.6V rail, and is accurate to within ±1°C at room temperature, including all error intrinsic to the Vishay PTS Class F0.3 Variant RTD. It covers the temperature ...

Circuit LTspice 

 

LTC6244 High Speed Peak Detector

Hassan Kelley - Field Applications Engineer
Gabino Alonso - Strategic Marketing Engineer
Aug 1st 2016
Introduction Peak detectors capture the extrema of the voltage signal at its input. A positive peak detector captures the most positive point of the input signal and a negative peak detector captures the most negative point of the input signal. Ideally the output of the peak detector circuit tracks or follows the input voltage ...

Blog Post Circuit LTspice 

 

LTC6268-10 Oscilloscope Differential Probe

Dec 1st 2015
The LTC6268-10 is a single 4GHz FETinput operational amplifier with extremely low input bias current and low input capacitance. It also features low input-referred current noise and voltage noise making it an ideal choice for high speed transimpedance amplifiers, and high-impedance sensor amplifiers. It is a decompensated op ...

Circuit LTspice 

 

LTC6269-10 20kΩ Gain 210MHz Transimpedance Amplifier

Apr 7th 2015
The LTC®6268-10/LTC6269-10 is a single/dual 4GHz FET-input operational amplifier with extremely low input bias current and low input capacitance. It also features low input-referred current noise and voltage noise making it an ideal choice for high speed transimpedance amplifiers, and high-impedance sensor amplifiers. It ...

Circuit 

 

LTC6268 20kΩ Gain 65MHz Trans-Impedance Amplifier

Apr 7th 2015
The LTC®6268/LTC6269 is a single/dual 500MHz FET-input operational amplifier with extremely low input bias current and low input capacitance. It also features low inputreferred current noise and voltage noise making it an ideal choice for high speed transimpedance amplifiers, CCD output buffers, and high-impedance sensor ...

Circuit 

 

LTC6091 Multiplexer Application

Jul 14th 2014
The LTC®6091 is a dual, high voltage precision operational amplifier. The low noise, low bias current input stage is ideal for high gain configurations. The LTC6091 has low input offset voltage, a rail-to-rail output stage, and can be run from a single 140V or split ±70V supplies. ...

Circuit 

 

LTC6091 High Voltage Analog MUX

Jul 14th 2014
The LTC®6091 is a dual, high voltage precision operational amplifier. The low noise, low bias current input stage is ideal for high gain configurations. The LTC6091 has low input offset voltage, a rail-to-rail output stage, and can be run from a single 140V or split ±70V supplies. ...

Circuit 

 

LTC6091 Wide Common Mode Range 10x Gain Instrumentation Amplifier Typically <1mV Input-Referred Error

Jul 14th 2014
The LTC®6091 is a dual, high voltage precision operational amplifier. The low noise, low bias current input stage is ideal for high gain configurations. The LTC6091 has low input offset voltage, a rail-to-rail output stage, and can be run from a single 140V or split ±70V supplies. ...

Circuit 

 

Extended Dynamic Range 1MΩ Transimpedance Photodiode Amplifier

Oct 30th 2012
The LTC6090 is a high voltage precision operational amplifier. The low noise, low bias current input stage is ideal for high gain configurations. The LTC6090 has low input offset voltage, a rail-to-rail output stage, and can be run from a single 140V or split ±70V supplies. ...

Circuit 

 

700kHz, 1MΩ Single Supply Photodiode Amplifier

Oct 2nd 2009
The measured output noise for this circuit was 153uVrms measured on a 1MHz bandwidth. Supply current was a low 2.2mA. ...

Circuit 

 

Single Supply Shock/Vibration Sensor Amplifier

Sep 5th 2007
The LTC6087/LTC6088 are dual/quad, low noise, low offset, rail-to-rail input/output, unity-gain stable CMOS operational amplifiers that feature 1pA of input bias current. A 14MHz gain bandwidth and 7.2V/μs slew rate, combined with low noise (10nV/√Hz) and a low 0.75mV offset, make the LTC6087/LTC6088 useful in a variety of ...

Circuit 

 

Precision Nanoamp Bidirectional Current Source

Aug 6th 2007
This circuit sources and sinks just nanoamps of current with precision due to the low input bias current of the CMOS op amps. A buffered difference amplifier and an integrator force the voltage across a 10Megaohm set resistor to be 1/1000 of the control input voltage in either polarity. ...

Circuit 

 

LTC6081 Two Op Amp Instrumentation Amplifier

Aug 6th 2007
Instrumentation amplifiers present a high input impedance to a differential input signal source and provide a single ended output. This circuit uses the non-inverting inputs of each amplifier of the dual LTC6081 for the differential input terminals. The gain is set with external resistors to over 1000. A CMRR trim cancels the ...

Circuit LTspice 

 

Low Side Current Sense

Aug 6th 2007
Sensing the amount of current through a load on the low side has the disadvantage of raising the return connection to the load from ground. The advantage of such an approach is that it is very easy to implement using a basic non-inverting gain stage. The LTC6081 operates linearly down to ground also in this single supply example. ...

Circuit 

 

LTC6081 Single Supply Strain Gauge Amplifier

Aug 6th 2007
A dual CMOS amplifier with low supply voltage operation and rail to rail input and output performance makes single supply operation easy. This circuit provides a gain of 1001 to the small differential input signal from a low voltage strain gauge bridge transducer. High input impedance allows for high valued input resistors to ...

Circuit LTspice 

 

LTC6081 Shock Sensor Amplifier (Accelerometer)

Aug 6th 2007
A shock sensor is a capacitive piezoelectric element which generates a charge under physical acceleration. This charge can be converted to a voltage and filtered using high valued resistors and a high input impedance CMOS amplifier such as the LTC6081. This circuit has a gain of 100 and output 109mV per g of acceleration. ...

Circuit LTspice 

 

Reference Buffer

Jan 10th 2007
The control voltage, Vin, is converted to a charge on a capacitor that is referenced to ground. This charge is transferred to place a differential voltage across the output current programming resistor. The output current then flows into a ground referenced load for a precision single supply circuit without the need for a voltage ...

Circuit 

 

LTC6240 Piezoelectric Shock Sensor Amplifier

Jan 10th 2007
A piezoelectric shock sensor generates a charge when physically accelerated. This charge is transferred to the smaller feedback capacitor. In this circuit a gain of 100 is given to the sensor’s open circuit voltage. ...

Circuit 

 

LTC6240 Low Noise 1M Trans-Impedance Amplifier

Jan 10th 2007
By using a 10Megaohm resistor, with a noise of 400nV/rtHz, for transimpedance gain and then attenuating the signal by 10 results in an equivalent gain of 1Megaohm with only 40nV/rtHz of noise. This is less than 1/3 the noise of a single stage TIA with a 1Megaohm resistor. ...

Circuit 

 

Low Noise Low Power DC Accurate Single Supply Photodiode Amplifier

Sep 21st 2006
A low noise JFET Q1 acts as a current buffer, with R2 and R3 imposing a low frequency gain of approximately 1. ...

Circuit 

 

Large Area Photodiode Bootstrapping

Aug 22nd 2006
Large area photodiodes come with a large capacitance, typically on the order of 3000pF or larger. This capacitance to ground at the input of a transimpedance amplifier has a significant effect on the output noise of the circuit as the noise gain increases dramatically at higher frequencies. The addition of a low noise JFET ...

Circuit 

 

LTC6244 Low Noise AC Difference Amplifier

Aug 22nd 2006
Piezoelectric and LVDT (Linear Variable Differential Transformer) sensors provide differential ac output signals. In addition to a standard difference amplifier a secend amplifier can be used as a dc servo amplifier to force an output dc bias potential in single supply applications. This difference amplifier is dc coupled but ...

Circuit LTspice 

 

Wide Bandwidth Photodiode Amplifier

Aug 22nd 2006
Wide bandwidth performance from a small photodiode requires minimizing the total input capacitance. In this circuit the amplifier's differential input capacitance is bootstrapped by the feedback with R1 and R2. Choosing the amplifier input that is at the corner of the package for the dual LTC6244 also minimizes pin-to-pin capacitance. ...

Circuit 

 

Very Low Noise Large Area Photodiode Amplifier

Aug 22nd 2006
Large area photodiodes come with a large capacitance, typically on the order of 3000pF or larger. This capacitance to ground at the input of a transimpedance amplifier has a significant effect on the output noise of the circuit as the noise gain increases dramatically at higher frequencies. AC coupling a bootstrap JFET across ...

Circuit 

 

Small Area Photodiode in Normal TIA Configuration

Aug 22nd 2006
Small area photodiodes have low capacitance. To maintain low noise operation it is important to keep the input capacitance low so that the miniscule input noise current of the CMOS amplifier, and not the voltage noise, dominates the overall circuit noise. The total input capacitance from the amplifier in this circuit is the ...

Circuit 

 

Low Noise Fully Differential Buffer/Amplifier

Aug 22nd 2006
Useful in RFID baseband signal processing is a differential amplifier with an input impedance set to match the differential output impedance of a RF demodulator. The differential input impedance is 2*Rin and the gain is Rg/Rin. Capacitors Cf and Cin can be used to set the bandwidth of the amplifier. For DC biasing the common ...

Circuit 

 

LTC6078 pH Probe Amplifier

Aug 16th 2005
pH Probe amplifiers require buffer amplifiers with an input impedance greater than 10^13 ohms. Without loading the probe, an output of approximately 60mV/pH unit is produce. The thermistor is added to provide first order compensation for the inherent temperature coefficient of the pH probe output. ...

Circuit LTspice 

 

Thermocouple Thermometer with Cold Junction Compensation

Aug 16th 2005
The LTC2997 is a high-accuracy analog output temperature sensor. It converts the temperature of an external sensor or its own temperature to an analog voltage output. A built-in algorithm eliminates errors due to series resistance between the LTC2997 and the sensor diode. ...

Circuit 

 

Reduced Power Infra-Red Diode Driver

Aug 16th 2005
Infra-Red LEDs can be used as continuously operating beams of light. Sensing a break in the path of light between the source and a photodiode receiver is often used in safety and alarm systems. To extend the run-time of the light source, the diode conducts the minimum current necessary, in this case 10mA. Controlling the duty ...

Circuit 

 

Six Decade Current Sensing Log Amplifier

Aug 16th 2005
The low pA's of bias current of CMOS amplifiers make them suitable for high input impedance current sensing applications. By taking advantage of the logarithmic relationship of a transistor base-emitter voltage to it's collector current a very wide range of measured input current can be converted to a voltage. In this circuit ...

Circuit 

 

Accelerometer Signal Conditioner

Aug 16th 2005
A piezoelectric accelerometer responds to any physical movement by generating a charge proportional to the acceleration of the movement. This sensor has a capacitance of 750pF which produces a charge of 60pC per g of gravitational force. This charge is transferred to the 1000pF feedback capacitor for an output of 60mV/g. ...

Circuit 

 

LTC6078 Precision Ground Referenced Voltage Controlled Current Source

Aug 16th 2005
The control voltage, Vin, is converted to a charge on a capacitor that is referenced to ground. This charge is transferred to place a differential voltage across the output current programming resistor. The output current then flows into a ground referenced load for a precision single supply circuit without the need for a voltage ...

Circuit 

 

Micropower Photodiode Amplifier

Aug 16th 2005
This is a basic photodiode amplifier which converts the tiny current output by the diode in response to light intensity to a buffered low impedance voltage source. CMOS amplifier's allow for the use of large feedback resistors and add very little input bias error current. For this Infra-Red diode the output changes 600mV for ...

Circuit 

 

LTC6078 60Hz Notch Filter

Aug 16th 2005
High input impedance amplifiers are ideal for buffering high impedance networks. Here a twin-T notch filter is shown to reject 60Hz signal content by more the 60dB. Small size, low valued capacitors can be used at such a low frequency with high valued resistors when using a CMOS op amp. ...

Circuit LTspice 

 

2.7V to 5.5V Precision High Side Current Sense

Aug 16th 2005
This high side current sense amplifier works down to 2.7V. Even with such a low supply voltage, accuracy of the voltage sensed across resistor Rs is preserved due to the very low voltage offset error of the LTC6078 amplifier (7uV typical). ...

Circuit 

 

Paralleling Amplifiers to Reduce Noise

Jun 27th 2005
In high gain circuits noise reduction is an important consideration. Paralleling four amplifiers will reduce the total noise of the circuit by a factor of two. The output noise of each amplifier, enOUTx, is attenuated by four and summed at the output terminal. Since noise from uncorrelated sources is summed in RMS fashion the ...

Circuit 

 

Ultra-Low Noise 1Mohm 150kHz Photodiode Amplifier

Jun 27th 2005
The low current noise of the LTC6242 makes the noise of this circuit dominated by the 1Mohm resistor used to convert the photodiode current to a voltage. ...

Circuit 

 

Low Noise Non-Inverting Shock Sensor Amplifier

Jun 27th 2005
The shock sensor charge is converted to a voltage and amplified with a precision resistor ratio for gain accuracy. Paralleling amplifiers reduces noise. ...

Circuit 

 

Single Ended Input-Differential Output Amplifier

Jun 27th 2005
A dual amplifier package can is configured to convert a single ended ground reference input signal to a differential output signal. Low bias current allows for a high input impedance of 200Kohm and the tight offset matching of the amplifiers provides a differential output dc offset of only 40uV. ...

Circuit 

 

Precision Sample and Hold Amplifier

Sep 3rd 2004
CMOS amplifiers are very good for use in Sample-and-Hold circuits because the pA's of bias current does not drain off charge held on the hold capacitor. A dual amplifier can be used to buffer the input signal and also the hold capacitor. The slew rate of the circuit is limited by the output current limit of the input amplifier ...

Circuit 

 

LTC2054 Ultra-Precision, Wide Dynamic Range 10Hz Bandwidth Photodiode Amplifier

Jan 20th 2004
The low input bias current and input noise current, combined with low voltage offset, provide a precision signal monitor. A high degree of input sensitivity is provided to the circuit by the large dynamic range, characterized by low input offset and high DC gain of the LTC2054. ...

Circuit 

 

LTC6081/LT1025 Type K Thermocouple Signal Conditioner with ±350V Protection from Accidental Contact and Cold Junction Compensation

Dec 9th 2003
A high input impedance amplifier permits the use of large valued input resistors and retains signal accuracy. This is very useful for protecting both the amplifier and cold junction compensator in thermocouple applications as the sense element can often be inadvertently connected to destructive voltage potentials. The 1MΩ ...

Circuit 

 

Precision Photodiode Amplifier

Feb 1st 2001
The LT1880 provides a high degree of precision with very low bias current (IB = 150pA typical). Total output offset is below 262mV, worst-case, over temperature (0°C to 70°C). With a 5V output swing this implies a minimum 86dB dynamic range. ...

Circuit 

 

40nVpp Noise, 0.05uV/C Drift, Chopped FET Amplifier

Jan 30th 2001
For very high precision low frequency applications, chopping the dc input signal to create an ac signal and then synchronously demodulating the signal to restore the dc value eliminates all static dc errors of the components used. This is a high gain (Av=1001) example with excellent low offset voltage and drift with temperature ...

Circuit 

 

Paralleled Voltage Regulators with Balanced Load Sharing

Jul 15th 1999
Paralleling voltage regulators to provide mode load current is a common technique. Forcing the amplifiers to share the load current equally is called ballasting. Using a precision low offset voltage amplifier to sense the output current from each regulator requires just milli-ohms of resistance, typically just a pcb circuit ...

Circuit 

 

Relative Humidity Sensor

Mar 2nd 1999
This sensor is a capacitive element that changes value with humidity. By charging the sensor with a fixed current for a fixed time interval, a voltage is developed that is directly proportional to the sensor capacitance value. ...

Circuit 

 

LT1792/LT1464 Low Noise Hydrophone Amplifier with DC Servo

Nov 26th 1996
These op amps are best used with very high impedance transducers. The low noise hydrophone amplifier in this figure is an application where the LT1792 excels. The AC current output of the hydrophone is converted to a voltage output by the 100M input resistor (R8). This signal is amplified by the R3/R2 ratio. DC leakage currents ...

Circuit LTspice 

 

Logging Photodiode JFET Amplifier with 1pA Input Bias Current

Jul 1st 1996
The 1pA input bias current contributes only 0.4fA/rtHz of current noise or 0.4nV/rtHz voltage noise with a 1Mohm source impedance. Photodiode current is converted to a voltage by the first op amp and D1 and amplified by the first, second and third logarithmic compression amplifiers. ...

Circuit 

 

LT1169 Low Noise Hydrophone Amplifier with DC Servo

May 2nd 1994
The LT1169 achieves a new standard of excellence in noise performance for a dual JFET op amp. For the first time low voltage noise (6nV/rtHz) is simultaneously offered with extremely low current noise (1fA/rtHz), providing the lowest total noise for high impedance transducer applications. Unlike most JFET op amps, the very low ...

Circuit 

 

Low Distortion, Crystal Stabilized Oscillator

Feb 14th 1994
Variation on the classic sine-wave Wien-bridge oscillator. The op amp to the left forces a symmetric signal to develop across the bridge, while the negative tempco of the lamp filament stabilizes the amplitude of oscillation by the right-side section. ...

Circuit 

 

Analog Divider

Feb 14th 1994
The input section forms a precision charge balancing action whereby the capacitor switching rate depends on the ratio of A/B. The output section, driven by the same switching frequency, forms a precision F/V conversion to provide the A/B output signal. ...

Circuit 

 

100dB Range Logarithmic Photodiode Amplifier

Feb 14th 1994
The photodiode current is processed by a form of trans-impedance amplifier (TIA) that has a logarithmic I to V characteristic. The Vbe of the logging transistor is scaled and offset to properly represent the desired dynamic range. To prevent temperature variation from affecting the accuracy, another loop is used as a stabilized ...

Circuit 

 

Accelerometer Amplifier with DC Servo

Aug 20th 1993
The feedback integrator amplifies the 100 Megohm feedback resistance to behave like about 1Gigohm, extending the low-frequency response downward by about an order of magnitude. ...

Circuit 

 

LT1113 Low Noise Hydrophone Amplifier with DC Servo

Aug 20th 1993
The LT1113 achieves a new standard of excellence in noise performance for a dual JFET op amp. The 4.5nV/ÖHz 1kHz noise combined with low current noise and picoampere bias currents makes the LT1113 an ideal choice for amplifying low level signals from high impedance capacitive transducers. ...

Circuit LTspice 

 

DC Accurate Composite Amplifier

Apr 1st 1992
Most individual op amp devices are optimized for either DC precision or for high speed operation. A composite amplifier configuration uses a precision low offset and drift amplifier to control the dc biasing of a high speed amplifier. This circuit has a gain bandwidth product of 1.25MHz yet an input offset voltage of only 25uV ...

Circuit 

 

LT1792/LT1097 Low Noise Hydrophone Amplifier with DC Servo

Dec 1st 1989
The LT1792 achieves a new standard of excellence in noise performance for a JFET op amp. The 4.2nV/ÖHz voltage noise combined with low current noise and picoampere bias currents make the LT1792 an ideal choice for amplifying low level signals from high impedance capacitive transducers. ...

Circuit LTspice 

 

Low Noise, Wideband, Gain = 100 Amplifi er with High Input Impedance

Jan 1st 1987
Averaging of three identical input stages reduces random noise addition by √3. Each input stage has a gain of about 10.2, and the second stage adder is trimmed for an accurate overall 100x. ...

Circuit 

 

Kelvin-Sensed Temperature Sensor Amplifier for –50°C to 150°C Platinum RTD from 10V Reference

Jan 1st 1987
The LT1012 is an internally compensated universal precision operational amplifier which can be used in practically all precision applications. The LT1012 combines picoampere bias currents (which are maintained over the full –55°C to 125°C temperature range), microvolt offset voltage (and low drift with time and temperature), ...

Circuit 

 

Exponential Voltage-to-Frequency Converter for Music Synthesizers

Jan 1st 1987
Logarithmic characteristic of BJT is used to provide an exponential control effect on V/F function. By using a multiple transistor array, a thermal stabilization circuit assures a constant operating point for the log function. ...

Circuit 

 

Bipolar Input (AC) V/F Converter

Jan 1st 1987
Input integrator uses precision full-wave rectifier for an absolute-value integration charge. Since not ground referenced, the integration ramp is sensed by a diff amp structure that drives the V/F output comparator. A simple comparison forms a sign bit. ...

Circuit 

 

Temperature-to-Frequency Converter

Jan 1st 1987
Precision oscillator structure uses SCR effect to discharge integration capacitor. A temperature dependent device (LM134) effects the integrator trip point to form a variable interval. An output transistor detects the reset action and forms a logic pulse. ...

Circuit 

 

Current Output, High Speed, High Input Impedance Instrumentation Amplifi er

Jan 1st 1987
This is a variation on the standard 3-stage implementation of an Instrumentation Amplifier function. The output sense resistor, along with the extra op amp for feedback sensing, form a Howland current-source structure for generating precision output current. ...

Circuit 

 

Wideband, High Input Impedance, Gain = 1000 Amplifi er

Jan 1st 1987
The gain is distributed equally between four amplifier sections in cascade, so the gain of each section is about 5.6. Distributing the gain uniformly provides the best bandwidth. Trimming of the final stage corrects for resistor variances so that overall gain is 1000x. ...

Circuit 

 

1Hz to 10kHz Voltage to Frequency Converter

Jan 1st 1987
JFET inputs with anti phase-reversal circuitry allow the LTC1055/56 to be used as a precision, ultra-high impedance comparator. The precision provides for very high linearity of the V/F generation while the high speed allows a large frequency range of operation. ...

Circuit 

 

Fast, 16-Bit Current Comparator

Jan 1st 1987
Precision op-amp used as pre-comparator. Schottky diodes in feedback limit output swing of amplifier to minimize slew delay. Resistive input structure can be tailored for different trip points; this one detects a current sink of >50uA at the input ...

Circuit 

 

LT1055 ±120V Output Precision Op Amp

Jan 1st 1987
Simple shunt regulators provide normal supply levels to the op amp and the external open-loop gain and buffer structure extends the output swing to nearly the high-voltage rails. Output transistors are protected by current-limiting. ...

Circuit LTspice