Frequency Response Curve
Next, we can see that the frequency response of any circuit is a change in its behavior with changes in input signal frequency, as it indicates the frequency band, which remains quite constant above the output (and gain). The frequency range large or small between εL and εH is called circuit bandwidth. Thus, we can determine the voltage gain (in dB) at a glance for any sinusoidal input in a certain frequency range. As mentioned above, the Bode diagram is a logarithmic representation of frequency response. Most modern sound amplifiers have a flat frequency response, as shown above, in the entire range of sound frequencies from 20 Hz to 20 kHz. For an audio amplifier, this frequency range is called Bandwidth (BW) and is primarily determined by the frequency response of the circuit. Frequency points εL and εH relate to the lower corner or cutting frequency and upper corner or cutting frequency points respectively, indicating that circuit gain decreases at high and low frequencies. These points on a frequency response curve are commonly known as -3dB (decibel) points. Therefore, bandwidth is simply given as follows: Decibels (dB), which are 1/10 of the waist (B), are a common nonlinear unit for measuring gain and are defined as 20log10(A), where A is the decimal gain drawn on the y-axis. . Zero decibels (0dB) correspond to a size function of the unit that outputs the maximum output. In other words, since there is no weakening at this frequency level, 0dB occurs when Vout = Vin is formed and given as follows:
From the Bode chart above, we see that the output at two corners or cutting frequency points has decreased from 0dB to -3dB and continues to fall at a constant rate. This decrease or decrease in earnings is commonly known as the rolling region of the frequency response curve. In all basic single-row amplifier and filter circuits, this roll-off speed is defined as 20dB/ten years, equivalent to a 6dB/octave speed. These values are multiplied by the order of the circuit.
These -3dB corner frequency points define the frequency at which the output gain is reduced to 70.71% of the maximum value. Then we can accurately say that the point -3dB is also the frequency at which the maximum value of the systems' earnings drops to 0.707.
Frequency Response at -3dB
The -3dB point is also known as half power points, since the output power at these corner frequencies will be half the maximum 0dB as shown. Therefore, the amount of output power transmitted to the load is effectively "halved" at the cutting frequency, and therefore the bandwidth (BW) of the frequency response curve can also be defined as the frequency range between these two half power points. . We use 20log10 (Av) for voltage gain and 20log10 (Ai) for current gain and 10log10 (Ap) for power gain. Keep in mind that the multiplication factor with 20 does not mean that the decibel is twice as high as 10, since it is a unit of the power ratio and there is no measure of the actual power level. In addition, gain in dB can be positive or negative, indicating a positive gain and a negative value weakening. Then we can present the relationship between voltage, current and power gain in the table below.
Decibel Gain Equivalents
|dB Gain||Voltage or Current Gain 20log10(A)||Power Gain 10log10(A)|
|-3||0.7071 or 1/√2||0.5|
|3||1,414 or √2||2|
OPAMPs can have open loop voltage gains (AVO) exceeding 1,000,000 or 100dB.
If an electronic system produces an output voltage of 24mV when a 12mV signal is applied, calculate the decibel value of the system output voltage.
If the output power of an audio amplifier is measured at 10W when the signal frequency is 1kHz and 1W when the signal frequency is 10kHz. Calculate the dB change in power.
In this context, we saw how the frequency range on which an electronic circuit works is determined by the frequency response. The frequency response of a device or circuit defines how its gain or amount of signal allowed changes with the frequency, allowing it to operate in a specific range of signal frequencies. Bode graphics are graphical representations of the frequency response properties of circuits and can therefore be used to solve design problems. Usually the circuits gain size and phase functions are shown in separate graphs using the logarithmic frequency scale along the x-axis. Bandwidth is the frequency range at which a circuit operates between the upper and lower cutting frequency points. These cutting or corner frequency points indicate frequencies where the power associated with the output drops to half the maximum value. These half-power points correspond to a 3dB (0.7071) earnings drop based on the maximum dB value. Most amplifiers and filters feature a flat frequency response in which the bandwidth or transition band portion of the circuit is flat and constant in a wide frequency range. Resonance circuits are designed to bypass a number of frequencies and block others. They are constructed using resistors, inductors and capacitors, whose colorances vary according to frequency.