Month: February 2015

Positive Output Precision Voltage Limiter

This circuit limits its output to a positive- going output only; negative output is clamped to ground. For negative inputs, D1 conducts and R2 provides negative feedback into U1’s summing junction. For positive inputs, D2 conducts and holds the summing junction to 0V. Thus the output across RL can only be positive. This characteristic is handy when driving single-supply amplifiers or unipolar A/D converters. For a negative output simply reverse D1 & D2. As shown, this circuit is a unity- gain inverter but it is also capable of providing voltage gain. Av = – 2 / R1. (Circuit is created by Neil P. Albaugh,  TI – Tucson)

Positive Output Precision Voltage Limiter circuit:

Positive output voltage limeter-blog

 

Online Simulation of the Positive Output Precision Voltage Limiter Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or watch our tutorial video! 

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Online Simulation a Transimpedance Amplifier Circuit

This fast photodiode transimpedance amplifier is based on a high- speed JFET- input op amp OPA657. This op amp is compensated for a minimum closed- loop gain of 7V/V but the capacitance of the photodiode plus the op amp input capacitance together with the feedback resistor R1 provides a noise gain at high frequency that allows stable operation. Compensation capacitor C1 optimizes the amplifier bandwidth / gain peaking tradeoff. Achieving this level of performance requires very careful layout and the circuit must be shielded to prevent noise pickup. (Circuit is created by Neil P. Albaugh,  TI- Tucson)

Transimpedance amplifier circuit:

transimpedance amplifier-blog

Online Simulation a Transimpedance Amplifier Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud and analyze the circuit yourself, or watch our tutorial video!  

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Comparator Window Settings

Conventional window comparators suffer interaction between the width and the center of the window; this makes adjusting these parameters time consuming. By using a precision dual 100uA current reference (REF200), this interaction is eliminated. The width of the comparator window is determined by the reference current and the value of P1: V = 100uA * 20k. The DC voltage of the window center is set by the % rotation of the potentiometer P1. With the pot at its center (50%), the center of the comparator window is at zero volts– thus the window is +/-1V. The window center adjustment is illustrated below. (Circuit is created by Neil P. Albaugh  TI- Tucson)

Comparator Window Settings circuit:

comparator window settings-blog

Online Simulation of the Comparator Window Settings Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud and analyze the circuit yourself, or watch our tutorial video!  

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Laser Energy Meter

 

An IVC102 switched integrator is also capable of integrating the output of a very fast detector. By storing the energy of a fast detector current pulse on its own capacitance (or on additional capacitance), this energy can then be transfered to the integrator feedback capacitor where it is held until it is sampled and the integrator can then be reset, awaiting the next pulse. Thus laser energy can be measured on a pulse- by- pulse basis. Needless to say, It is necessary to sync the integrator timing with the laser Q- switch. The simulated detector output pulse was 10mA peak with a 10ns width. Charge is stored on Cs until it is transfered when S1 closes. To prevent droop error due to shunt resistance Rs and the input bias current of U1, S1 should be closed a few microseconds after the laser pulse. The IVC102 can integrate a positive- output or negative- output detector. Lower sensitivity can be achieved by paralleling C2, C3, or an external capacitance. Bypass capacitors are not shown.  (Circuit is created by Neil P. Albaugh  TI- Tucson)

 Laser Energy Meter circuit:

Laser Energy meter-blog

Online Simulation of the Laser Energy Meter Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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DAC Interface Circuit

This “DAC Interface”  circuit is a precision buffer amplifier for a DAC output. It is scaled to provide a 10V output @ 10mA with a +1V input voltage. This type of current source can be very useful in industrial interface applications.  A R-R output op amp with an input common-mode
range that includes its negative supply rail, such as an OPA251, is required for single- supply operation.  An external NPN transistor  is used to off- load the circuit power dissipation from the precision op amp U1. Re- scaling this circuit with other transistors can result in output current capability of a many amps. (Circuit is created by Neil P. Albaugh  TI – Tucson)

DAC Interface Circuit:

DAC interface-blog

 

Online Simulation of the DAC Interface Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

 

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Comparator With AC Hysteresis

Using AC hysteresis solves the threshold offset problem caused by conventional DC hysteresis. Place a small capacitor to feed back the output edge transition into the comparator non- inverting input to provide momentary positive feedback. This sharpens the comparator response as well as reducing the tendency to “chatter” at the switching point. If the RC time constant of R1C1 is << the waveform period, the comparator trip point hysteresis will have settled back to 0V by the time the next threshold- crossing takes place. (Circuit is created by Neil P. Albaugh  TI- Tucson)

Comparator With AC Hysteresis circuit:

comparator with AC hysteresis3

 

Online Simulation of a Comparator with AC Hysteresis circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

 Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Zoom Amplifier

This “unusual zoom amplifier circuit” allows you to “zero out” a DC voltage and then amplify a small AC signal which is superimposed on the much larger DC level. When switch SW1 is closed, both INA128 inputs see the same AC + DC level and its high common- mode rejection results in zero volts output. When SW1 is opened, the DC level is stored on C1 but now the AC signal is applied to only the inverting input where it is amplified by a factor of 1000x. The droop rate of C1 depends on the leakage of SW1 and the input bias current of U1.Using a glass reed relay and an INA116 (Ib = 5fA typ), extremely low droop rate can be achieved. A high insulation resistance dielectric capacitor is necessary– teflon, polystyrene, etc. (Circuit is created by Neil P. Albaugh  TI- Tucson)

Zoom amplifier circuit:

Zoom amplifier-blog

 

Online Simulation of a Zoom  Amplifier Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Current Shunt Amplifier

This current shunt monitor circuit allows a current measurement to be made by measuring the voltage drop across a shunt resistor in the “high side” of a power supply. The INA193 is capable of operating with a common- mode voltage of up to +80V and its CMV range is not a function of
its supply voltage.  The INA193 provides a differential voltage gain of 20V/V and its recommended full- scale input  voltage is 100mV.  An INA194 provides a gain of 50V/V and an INA195 provides a gain of 100V/V. R1 & R2 together with C2, C3, & C4 provide differential and common-mode filtering and are recommended for switching power supplies. The two resistors should be carefully matched (1% tolerance) as well as capacitors C3 & C4 (5% or better tolerance). Resistors of 100 ohms will give a gain error of slightly under 2%. (Circuit is created by Neil P. Albaugh,  TI – Tucson)

Current Shunt Amplifier circuit:

Current shunt amplifier-blog

Online Simulation of the Current Shunt Amplifier Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Proportional- Integral Temperature Control

A high- accuracy temperature control amplifier can be realized with a proportional- integral amplifier response; the integrator function drives the steady- state error to zero.  An autozero instrumentation amplifier INA326 achieves very low offset and drift as well as virtually eliminating the loop error due to 1/f noise. R6 is used simply to provide a feedback path during a DC analysis. This circuit requires an overall feedback path (TEC, etc) to achieve a steady-state operating point. This amplifier allows temperature control loop stability within in a few tens of milli- degrees. Bypass capacitors are not shown. This circuit can be used with a DRV593 or an OPA569 TEC driver circuit. (Circuit is created by Neil P. Albaugh  TI – Tucson)

     Proportional- Integral Temperature Control circuit:

proportional integral temperature control-blog

 

Online Simulation of the Proportional- Integral Temperature Control Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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Capacitance Multiplier

A “capacitance multiplier” circuit can increase the effective value of a small capacitor C1 to a much larger value. The capacitance  seen at Vout is: Cout = C1 * R1/R3. Note that this circuit is only for a ground- referenced capacitor. Rs = R3. The output capacitance can be verified by placing an AC source in series with a resistor tied to Vout and running an AC frequency  response analysis. As seen in the result below, the 100pF capacitor has been multiplied by 1,000. Bypass capacitors are not shown.  (From a NSC app note) Circuit is created by Neil P. Albaugh  TI – Tucson

Capacitance Multiplier circuit: capacitance multiplier for blog

Online Simulation of the Capacitance Multiplier Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

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