Antilog amplifiers along with log amplifiers are used to perform analogue computations on the input signals. The circuit of an antilog amplifier. But if diode current is too low then the OP Amp input offsets become Then finally choose a max temp difference of the log and antilog diodes. EXPERIMENT 8: Log and Antilog Amplifiers. Objectives: To understand the behavior of logarithmic and antilogarithmic amplifiers. Materials and Equipment.

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The final output is developed by an inverting amplifier with a voltage gain of —K2.

Observe that the left hand side terms of both equation 1 and anttilog 3 are same. Some integrated log amps have uncommitted elements allowing us to implement antilog amps. You have 4 volts and 5 volts as your inputs. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts. Company Table Recruiting Disciplines. Post as a guest Name.

Unclear what you’re asking. This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Documents Flashcards Lg checker. Very similar question from a month ago: It is called four-quadrant wntilog inputs and output can be positive or negative. IC log amps may cost about ten times the components needed to build a discrete-component log amp.

According to the virtual short conceptthe voltage at the inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal. Then verify your design specs with sweeping ampljfier on the inputs and compute the gain and offset errors vs input. As such, they can vary over a wide range of values. You’ve simulated it, so why do you ask if it works for you?


This relationship is shown in the following formula: I’m trying to build an analog multiplier that takes any two voltages and produces the product for them This is the basic layout of the circuit: Email Required, but never shown. A simple Anti log amplifier is shown below.

Log and AntiLog Amplifiers

Consider the voltage-input transdiode. So this is another tradeoff for diode size qmplifier bandwidth vs temp rise. A logarithmic amplifieror a log amplifieris an electronic circuit that produces an output that is proportional to the logarithm of the applied input. Sign up using Email and Password. Temperature compensation must correct both error sources.

logarthmic, anti logarthmic amplifiers | ECE Tutorials

The bulk size and Pd rating of the diode affects the thermal resistance and bulk resistance or ESR, and also junction capacitance and bandwidth. This section discusses about the op-amp based anti-logarithmic amplifier in detail. Using a p-n-p transistor changes the polarity of input signals acceptable but limits the logarithmic range because of the degraded performance of p-n-p transistors compared to n-p-n transistors www. Figure next slide shows the use of a second, matched, transistor for offset compensation and a temperature-dependent gain for gain compensation.

By summing the outputs of two log amplifiers, you get the logarithm of the product of the two original input voltages. To get the logarithm of a signal voltage use a Log amplifier.


Applying KCL at inverting node of opamp we get. They have numerous applications in electronics, such as: The circuit diagram of logarithmic amplifier is as shown below. Ziad Could this be used to perform division if you used a differential amplifier instead of a summing amplifier?

Gain of logarithmic amplifier.

Automated Classification of internet video content. V is voltage applied across diode; V t is the voltage equivalent of temperature. Negative voltages or currents can be first rectified and then applied to the log amp, but this adds the errors from the rectifier.

Alternatively, the log amp can be preceded by a precision current inverter. SPICE simulation of voltage multiplier using log and antilog amplifier. An anti-logarithmic amplifieror an anti-log amplifieris an electronic amplifieer that produces an output that is proportional to the anti-logarithm of the applied input. The current inverter in Figure below uses two matched n-p-n transistors and a precision op amp to achieve accurate current inversion.

Log and AntiLog Amplifiers

That means zero volts is applied at the non-inverting input terminal of the op-amp. By using our site, you acknowledge that you have read and understand our Cookie ZntilogPrivacy Policyand our Terms antiloy Service. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground.

Omitting R1 yields a currentinput log amp. The source impedance of voltage signals applied to the circuit must be small compared to R1.