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The Voltage-Amplifier Stage
Published in Douglas Self, Audio Power Amplifier Design, 2013
Diodes also have non-linear junction capacitance, and this acts in the same way as the non-linear Cbc of the VAS transistor to cause distortion; see Figure 7.12. This is one more piece of evidence that Cbc causes VAS HF distortion. The junction capacitance Cj of the 1N4148 diode is specified as 4.0 pF max at zero bias. The value at 20V reverse-bias (the average bias here) does not seem to be quoted but by extrapolation from data sheet graphs is about 3.2 pF. This compares with Cbc = 2.6 pF at Vce = 20V for the MPSA42. You would therefore expect the distortion to increase considerably— in fact, more than double — when a diode is placed across Cdom. This did not happen, and at present the only explanation seems to be that the diode junction capacitance is specified rather pessimistically.
High-accuracy resolver-to-linear signal converter
Published in International Journal of Electronics, 2018
W. Petchmaneelumka, P. Mano, K. Songsuwankit, V. Riewruja
The performance of the proposed technique is demonstrated by experimental implementation using commercial devices. The active devices used in this paper consist of signal diode 1N4148, opamp LF353, OTA CA3280, comparator LM339, analogue switch CD4066 and D flip flop CD4013. The matched resistors provided for the proposed scheme were selectively matched better than 0.1%. The resistors are assigned as Rh1 – Rh7 = 20 kΩ, Rh8 – Rh9 = 10 kΩ, R1 = R2 = R4 = 10 kΩ, R5 – R7 = 30 kΩ, RS = 2 kΩ and RV1 = RV2 = 1 kΩ. The resolver with the transformation ratio of 0.37 is used for this experiment. The excitation signal vex is set to 2.7 V peak amplitude with 3 kHz sinusoidal wave for the peak amplitude of the resolver output signals of 1 V, where the period Tex is calculated as 0.33 ms. Therefore, the peak amplitude of the shaft-angle signal vdem is equal to 1 V. The phase shift φ between the resolver signal and the excitation signal of approximately 28° is measured.
Hopf bifurcation, antimonotonicity and amplitude controls in the chaotic Toda jerk oscillator: analysis, circuit realization and combination synchronization in its fractional-order form
Published in Automatika, 2019
Justin Roger Mboupda Pone, Sifeu Takougang Kingni, Guy Richard Kol, Viet-Thanh Pham
The circuit of Figure 9 is built using four operational amplifiers OP_1 to OP_4, six resistors, three capacitors C1, C2, C3 of ceramic type and a simple diode D of reference 1N4148 which is used to implement the exponential nonlinearity. The expressions of voltage across the capacitors are obtained using the Kirchhoff voltage law as follows: where , , are the output voltages of the operational amplifiers OP_1, OP_2, OP_3, respectively. The parameter is the reversed saturation current, the parameter is the scaling factor while the parameter is the thermal voltage. The values of components in the circuit are selected as , , , the potentiometers and . Here the values of the parameters and can be chosen by varying the values of and , respectively. The circuit of Figure 9 is studied and the phased portrait observed on the oscilloscope is shown in Figure 10.
An Overview on MOSFET Drivers and Converter Applications
Published in Electric Power Components and Systems, 2021
Mustafa Ergin Şahin, Frede Blaabjerg
One of the other principles to accelerate the MOSFET speed rise circuits' turn-off operation is mentioned here. The turn-on speed is limited by the turn-off or reverses recovery speed, usually restricted by the power supply's rectifier element. The rapid switching behavior is specified by the diode's reverse recovery characteristics instead of the resistance of the gate drive circuit, as shown in Figure 11(a). Typical applications are about 150 mA for a 1N4148 diode and 300 mA for a BAS40 Schottky diode. The most known circuit for fast turn-off switching is given in Figure 11(b) [88].