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Optical Transmitters
Published in Jerry D. Gibson, The Communications Handbook, 2018
Alistair J. Price, Ken D. Pedrotti
Measurement of laser output while switching the input current between two levels indicates that the dynamic response of these diodes is not straightforward. When switching from low optical power to a higher power, there is first a turn-on delay, which has a random component. A rapid increase in power follows, ringing at the relaxation resonance frequency. An unwanted frequency modulation accompanies the ringing. The turn-off is a smooth exponential decay, which is somewhat slower than the turn-on transition time. Typical waveforms for various current levels are shown in Fig. 47.2. The turn-on delay decreases as the off-state (bias) current is increased. For many digital applications, the bias is carefully set close to the laser threshold current to minimize the turn-on delay while at the same time providing a high-extinction ratio.
Making Sounds with Analogue Electronics
Published in Russ Martin, Sound Synthesis and Sampling, 2012
Circuits that have a strong resonance at a specific frequency can be made to oscillate if a sudden input causes them to self-oscillate. This ‘ringing’ is usually a sine wave and it dies away at a rate which is dependent on how close to self-oscillation the circuit is. The nearer it is to oscillating, the longer the ringing will last. Some VCFs can be made to self-oscillate if their Q or resonance is high enough, and at Q values just below this, they will ring. Conversely, an oscillator can be ‘damped’ so that it does not self-oscillate, but it will then ring. Filters and oscillators are just different applications of resonant circuits.
Improved topology of high voltage gain DC-DC converter with boost stages
Published in International Journal of Electronics Letters, 2021
Shakeel Ahmad, Mashood Nasir, Jerzy Dąbrowski, Josep M. Guerrero
The switch current of the alternate topology of Prabhala et al. (2016) and, of the proposed converter is shown in Figure 8. The currents are measured in terms of the voltage across a 20 mΩ resistor. It can be observed that current spike in Mode-2 and 3 is significantly reduced. The ringing effect observed in the current waveforms is caused by the interaction of leakage inductance (including parasitic inductance of PCB) and MOSFET output capacitance. Voltage stress across the switch and voltage across the VM stage diodes of the proposed converter is presented in Figure 9. The peak OFF voltage of switch is 100 V while the diode peak reserve is measured as 200 V. Similarly, peak reserve voltage of 100 V across the output diode is shown in Figure 10.
Stability analysis and stabilisation of an amplifier with non-linearity compensation
Published in International Journal of Electronics Letters, 2018
As an example to test the stability of an amplifier with the negative impedance method, the main amplifier in Figure 1 has been designed to have a closed-loop gain of −4. The values of the components to realise the gain are chosen as RF = 2 kΩ, RG = 500 Ω. For the negative resistance circuit shown in Figure 5, the two resistors, R1 and R2, have been considered as R1 = R2 = 10 kΩ. Also, according to the negative impedance compensation theory and using Equation (9) in Wu et al. (2007), the value of the compensation component, RN, can be calculated as RN = 390 Ω. The stability can be tested by injecting step signal at the input and observing the output. In this case, a −0.1-V step signal with 0.1 μs delay was injected at the input. As shown in Figure 7, the example amplifier delivers an output with excessive overshoot (up to 0.614 V) and ringing (till 0.75 μs).
Evaluation of electromagnetic intrusion in brushless DC motor drive for electric vehicle applications with manifestation of mitigating the electromagnetic interference
Published in International Journal of Ambient Energy, 2020
M. Karthik, S. Usha, K. Venkateswaran, Hitesh Panchal, M. Suresh, V. Priya, K. K. Hinduja
When MOSFET operates at the high frequency, it produces a spark and makes distortion in output frequency as shown in Figure 3 which is known as ringing effect. The spike in the waveform shows the effect of ringing. It occurs due to turn ON and turn OFF of MOSFET with the internal parasitic Capacitance and inductance, which produces resonance and results in high-frequency ringing effect. It spreads EMI to nearby devices using conduction wire.