Column: Circuit drill
fixed at 5V (peak-to-peak).
• All circuit component values were kept unchanged, except the bias voltage (V2), which was varied from 1Vdc to 5Vdc, in 1Vdc increments.
• The temperature was kept at ambient 25o
C. Figure 3: Relation between the input and output voltages during input frequency changes
The impact of frequency on circuit performance Figure 3 shows the relationship between the applied frequencies, the bias voltage (V2) and the upward shift voltage. It can be seen that the circuit delivers a consistent and dependable performance over the whole frequency range from 1Hz to100kHz, correctly shifting the input signal by the same magnitude for each bias voltage, V2. This shows that the clipper circuit offers a satisfactory frequency-linked performance.
Figure 4: Output signal peak-to-peak magnitude at various frequencies and bias voltages
Figure 1, which uses a general-purpose op-amp, LF351, and a 1N914 diode. Throughout the experiment we fed a
sinusoidal signal into the clamper circuit, with a changing frequency from 1Hz to 100kHz, whilst keeping the bias voltage source (V2) the same. To evaluate the circuit’s performance, the amplitude of the upward shift in the input signal is evaluated at each frequency step during circuit operation. To obtain a complete spectrum of the circuit performance chart, the same operations were done for various bias voltage sources (V2).
Then we monitored two parameters,
as follows: (1) The upper shifts that occur to the input signal at various frequencies and various bias voltage sources (V2);
(2) The output signal’s peak-to-peak values at various frequencies and bias voltage source (V2).
The data was then plotted to
determine the relationship between these parameters. For the experiment we assumed the
following: • We kept the input signal magnitude
The impact of bias voltage on circuit performance The experiment also showed a connection between the bias voltage and the peak-to-peak amplitude of the output signal for a wide range of input frequencies. Figure 4 shows that the circuit can maintain a peak-to- peak signal output that is quite steady for signal frequencies above 11kHz. However, the output signal’s peak-to- peak magnitude is significantly distorted for frequencies below 11kHz. In addition, there’s a degree of distortion proportional to the level of bias voltage. We can conclude that the clamper
circuit offers steady performance for different input signal frequencies, especially between 1Hz and 100kHz. However, the peak-to-peak value of the output signal is only maintained for input frequencies over 11kHz, but not for those below 11kHz – where the generated signal is quite distorted. The output signal will exhibit a greater degree of distortion in proportion to the degree to which the bias voltage level is reduced. These results allow circuit designers
to compensate for the clamper circuits in different applications, and thoroughly test their circuits for the targeted frequencies.
www.electronicsworld.co.uk September 2023 09
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