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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Then verify your design specs with sweeping voltages on the inputs and compute the gain and offset errors vs input.

Omitting R1 yields a currentinput 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.

The K values control the R value which controls the diode current which can lead to errors if there is self heating which is the NTC Shockley Effect. Tony EE rocketscientist 62k 2 21 Consider the voltage-input transdiode. Then finally choose a max temp difference of the log and antilog diodes to avoid gain and offset errors. Some integrated log amps have uncommitted elements allowing us to implement antilog amps.

According to the virtual short conceptthe voltage at the inverting input terminal of op-amp will be equal to the voltage present at its non-inverting input terminal.

The electronic circuits which perform the mathematical operations such as logarithm and anti-logarithm exponential with an amplification are called as Logarithmic amplifier and Anti-Logarithmic amplifier respectively. Hence applying KCL at inverting terminal of opamp, we get.


Log And Anti Log Amplifiers

Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts. Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations.

The system bandwidth is narrower for small signals because emitter resistance increases for small currents. The circuit diagram of logarithmic amplifier is as shown below. Please note that these amplifiers fall under non-linear applications.

Anti log amplifier is one which provides output proportional to the anti log i. In the above circuit, the non-inverting input terminal of the op-amp is connected to ground.

Antilog amps are used together with log amps to perform analog computation. These basic circuits needs additional components to improove the overall performance, i. The two output voltages from the log amplifiers are added and inverted by the unity-gain summing amplifier to produce the following result: Logarithmic amplifier gives the output proportional to the logarithm of input signal.

Company Table Annd Disciplines.

Documents Flashcards Grammar checker. The diode apmlifier resistance also drops with rising log current until saturated where the bulk resistance limits the minimum resistance. Gain of logarithmic amplifier.

Log and AntiLog Amplifiers

This is the basic layout of the circuit: But if diode current is too low then the OP Amp input offsets become significant compared the the log1, log2 outputs. An op-amp based anti-logarithmic amplifier produces a voltage at the output, which is proportional to the anti-logarithm of the voltage that is applied to the diode connected to its inverting terminal. To investigate its stability, refer to the incremental model, where the BJT has been replaced by its common-base smallsignal model.


To get the logarithm of a signal voltage use a Log amplifier. ampllfier

Log and AntiLog Amplifiers

The source impedance of voltage signals applied to the circuit must be small compared to R1. V is voltage applied across diode; V t is the voltage equivalent of temperature. As such, they can vary over a wide amplifieg of values. Unclear what you’re asking. Matched temperature by thermal coupling is desired or minimize self heating for low T rise. They have numerous applications in electronics, such as: Figure next slide shows the use of a second, matched, transistor for offset compensation and a temperature-dependent gain for gain compensation.

logarthmic, anti logarthmic amplifiers | ECE Tutorials

SPICE simulation of voltage multiplier using log and antilog amplifier. An anti-logarithmic amplifieror an anti-log amplifieris an electronic circuit that produces an output that is proportional to the anti-logarithm of the applied input.

Please think about what you are doing in your simulation. The anti log amplifier can be redrawn as follows. Sign up using Facebook.

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