The Circuit Design Blog

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:

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

Laser Energy Meter Circuit

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:

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

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:

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

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:

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

Zoom amplifier circuit

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:

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