Introduction Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. Log and Antilog Amplifiers are non-linear circuits in which the output voltage is proportional to the logarithm (or exponent) of the input. ❖ It is well known that. 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.

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Applying Antilog on both sides we get. Consider the voltage-input transdiode.

Please think about what you are doing in your simulation. Antilog amps are used together with log amps to perform analog computation. Ziad Could this be used to perform division if you used a differential amplifier instead of a amplifiees amplifier?

Since the non inverting terminal of opamp is at ground potential. Very similar question from a month ago: A log amplifier is an amplifier for which the output voltage V out is K times the natural log of the input voltage V in.


Electronic amplifiers Electronics stubs. Please note that these amplifiers fall under non-linear applications. Retrieved from ” https: Sign up using Email and Password. The reverse saturation current for the diode doubles for every ten degree Celsius rise in temperature.

SPICE simulation of voltage multiplier using log and antilog amplifier.

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

This section discusses about the op-amp based anti-logarithmic amplifier in detail. To design a logarithm amplifier circuit, high performance op-amps like LM, LM, LM are commonly used and a compensated logarithm amplifier may include more than one. Then determines the required input bias current and offset must be to achieve this.

logarthmic, anti logarthmic amplifiers

The logarithmic circuit can be redrawn as follows. So, the voltage at the inverting input terminal will be zero volts. This relationship is shown in the following formula: Leave a Reply Cancel reply Your email address will not be published. Tony EE rocketscientist 62k 2 21 Observe that the left hand side terms of both equation 1 and equation 3 are same. Unclear what you’re asking. Logarithmic amplifier gives the output proportional to the logarithm of input signal.


That means zero volts is applied at ampplifiers non-inverting input terminal of the op-amp. Views Read Edit View history. The system bandwidth is narrower for small signals because emitter resistance increases for small currents.

Log amplifier – Wikipedia

Figure next slide shows the use of a second, matched, antolog for offset compensation and a temperature-dependent gain for gain compensation. I know there is problem with the last stage, the last opamp should give me gain: This can be expressed as. So this is another tradeoff for diode size vs bandwidth vs temp rise. Anti amplifiere amplifier is one which provides output proportional to the anti log i. Does this seem reasonable? Hence applying KCL at inverting terminal of opamp, we get.

D1 protects the base-emitter junction from excessive reverse voltages. 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.