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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Log-Antilog Log and antilog amp circuits include the same elements but arranged in different feedback configurations. To investigate its stability, refer to the incremental model, where the BJT has been replaced by its common-base smallsignal model.

As such, they can vary over a wide range of values. Ad get the logarithm of a signal voltage use a Log amplifier.

Log and AntiLog Amplifiers

It is obvious from the circuit shown above that negative feedback is provided from output to inverting terminal. Constant terms are omitted for simplicity. So, the voltage at its inverting input terminal will be zero volts. Logarithmic amplifier operation The circuit diagram of logarithmic amplifier is as shown below logarithmic amplifier. Ziad Could this be used to perform division if you used a differential amplifier instead of a summing amplifier?


Logarithmic amplifier llog the output proportional to the logarithm of input ,og.

Linear Integrated Circuits Applications Log And Anti Log Amplifiers

The diode dynamic resistance also drops with rising log current until saturated where the bulk resistance limits the minimum resistance. Then a properly working multiplier should give you 20 volts out.

You have 4 volts and 5 volts as your inputs. Anti log amplifier is one which provides output proportional to the anti log i. The circuit diagram of logarithmic amplifier is as shown below. Then finally choose a max temp difference of the log and antilog diodes to avoid gain and offset errors.


By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. By summing the outputs of two log amplifiers, you get the logarithm of the product of the two original input voltages. So this is another tradeoff for diode size vs bandwidth vs temp rise. An op-amp based anti-logarithmic amplifier anx 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.

The source impedance of voltage signals applied to the circuit must be small compared to R1. That means zero volts is applied at the non-inverting input terminal of the op-amp.


Log and AntiLog Amplifiers

The bulk antilo and Pd rating of the diode affects the thermal resistance and bulk resistance or ESR, and also junction capacitance and bandwidth. It means zero volts is applied to its non-inverting input terminal. The anti log amplifier can be redrawn as follows. V is voltage applied across diode; V antiloog is the voltage equivalent of temperature.

Post as a guest Name. These basic circuits needs additional components to improove the overall performance, i.

The current inverter in Figure below uses two matched n-p-n transistors and a precision op amp to achieve accurate amplifuer inversion. But if diode current is too low then the OP Amp input offsets become significant compared the the log1, log2 outputs. Email Required, but never shown. Documents Flashcards Grammar checker. Post Your Answer Discard 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.

This chapter discusses about the Logarithmic amplifier and Anti-Logarithmic amplifier in detail.