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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This relationship is shown in the following formula: In the above circuit, the non-inverting input terminal of the op-amp is connected to ground.

## logarthmic, anti logarthmic amplifiers

The reverse saturation current anhilog the diode doubles for every ten degree Celsius rise in temperature. As such, they can vary over a wide range of values.

The current inverter in Figure below uses two matched n-p-n transistors ahtilog a precision op amp to achieve accurate current inversion. Hence, it is very difficult to set the reference voltage for the circuit. I’m trying to build an analog multiplier that takes any two voltages and produces the product for them.

Then, by taking the antilogarithm, you get the product of the two input voltages as indicated in the following equations: Company Table Recruiting Disciplines. Alternatively, the log amp can be preceded by a precision current inverter. Due to the virtual ground at the op amp differential input. That means zero volts is applied at the non-inverting input terminal of the op-amp.

A simple Anti log amplifier is shown below. 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. This electronics-related article is a stub.

Retrieved from ” https: This page was last edited on 13 Septemberat A necessary condition for successful operation of a log amplifier is that the input voltage, V inis always positive. By using this site, you agree to the Terms of Use and Privacy Policy. You’ve simulated it, so why do you ask if it works for you?

Matched temperature by thermal coupling is desired or minimize self heating for low T rise. The final output is developed by an inverting amplifier with a voltage gain of —K2.

This section discusses about the op-amp based anti-logarithmic amplifier in detail. The bulk size and Pd rating of the diode affects the thermal resistance and bulk resistance or ESR, and also junction capacitance and bandwidth. SPICE simulation of voltage multiplier using log and antilog amplifier. Then verify your design specs with sweeping voltages on the inputs and compute the gain and offset errors vs input. As V in is positive, V antiloog is obliged to be amtilog since the op amp is in the inverting configuration and is large enough to forward bias the emitter-base junction of the BJT keeping it in the active mode of antjlog.

Gain of Anti log amplifier. Email Required, but never shown.

Applying KCL at antilot node of opamp we get. So, the voltage at its inverting input terminal will be zero volts. Using the concept of virtual short between the input terminals of an opamp the voltage at inverting terminal will be zero volts.

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## Log and AntiLog Amplifiers

Very similar question from a month ago: Sign up using Facebook. Post as a guest Name. 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. One usually starts with a spec for Input and Output voltage range and max error vs input.

Ampliciers applying KCL at inverting terminal of opamp, we get. I know there is problem with the last stage, the last opamp should give me gain: But if diode current is too low then the OP Amp input offsets become significant compared the the log1, log2 outputs. Electronic amplifiers Electronics stubs. Automated Classification of internet video content.

The source impedance of voltage signals applied to the circuit must be small compared to R1. Figure next slide shows the use of a second, matched, transistor for offset compensation and a temperature-dependent gain for gain compensation.

Anti log amplifier is one which provides output proportional to the anti log i. logg

### Log amplifier – Wikipedia

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D1 protects the base-emitter junction from excessive reverse voltages. Sign up or log in Sign up using Google.