I have simulated neural amplifier(using ota) I want to calculate dynamic range of my amplifier @1%thd.can anybody help me guide me in telling steps to calculate it in cadence?
Dear Mr. Sharma,
In order to determine the dynamic range of the amplifier you have to determine the input voltage of the amplifier to get certian thd as you said here the bound is 1 percent.
This ca n be achieved by biasing the amplifier at its operating point and then apply on it a sinusoidal waveform sin wt with w chosen in the midband frequency range where the frequency response of the amplifier is flat. Then increase the amplitude of the input voltage and evaluate the thd at the output waveform of the amplifier. It is so that as you increase the input voltage the output waveform gets more distorted. You make transient analysis in order to get the output waveform and then in order to get the thd you need to make fft to determine the fundamental, then you can calculate the thd= square root of ( Vorms^2- Vfrms^2)/ Vfrms, where Vorms is the rms value of the output volage and Vf rms is its fundamnetsl root mean square value
wish you success
Thanku sir
As you stated that increase the amplitude of the input voltage and evaluate the thd at the output waveform of the amplifier and at particular amplitude i will get 1% THD limit beyond which i cannot extend amplitude that value will be my Vmax and similarly i will decrease the amplitude of the input voltage and evaluate the thd at the output waveform of the amplifier and at a particular amplitude i will get 1% THD beyond which i cannot decrease amplitude that value will be my Vmin and from these values i should calculate DR. IS it so sir?
Dear Mr. Sharma,
I am sorry that i did not describe how to get the smallest possible value of the dynamic range. The smallest possible value is set by the noise produced by the amplifier. So, in order to get such threshold value you have to simulate with the noise model of the amplifier. that is you have to add the noise generated by all elements in the circuit and calculate the root mean square noise of the amplifier at the output Then you divide this value by the gain of the amplifier to get the minimum input voltage which you assume either equal to the rms value of the noise of multiple value of it to achieve a minimum signal to noise ratio say 10 times. This depends on the system in which the amplifier is used.
sir can u tell me about a book from where i can have more details of DR so later on i can refer too
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