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DC Transfer Analysis
Published in Pooja Mohindru, Pankaj Mohindru, Electronic Circuit Analysis using LTspice XVII Simulator, 2021
Pooja Mohindru, Pankaj Mohindru
An output impedance (a term) can be thought of as being an impedance (or resistance) that a load perceives when looking back into the terminals across which a load is connected with an input voltage equal to zero (i.e., the input V1 is short-circuited). In the equivalent circuit of a voltage divider, an output impedance (Thevenin’s resistance) is just the resistance Rout that is equal to two resistances R1 and R2 connected in parallel, that is, Rout=R1×R2(R1+R2)
Signal Conditioning and Output Devices
Published in Francis S. Tse, Ivan E. Morse, Measurement and Instrumentation in Engineering, 2018
The open-loop characteristics of an idealized op-amp shown in Fig. 6-1c are: The inputs are perfectly symmetrical; that is, there is no offset voltages.The input currents are zero; that is, input impedances at the terminals a and b are infinite.The output impedance is zero.The voltage gain for the differential input voltage Vab from a to b is infinite for all frequencies; that is, the op-amp is a dc amplifier with an infinite gain A.Since Vo = AVab, where Vo is finite and A is infinite, the differential voltage Vab = (Vb – Va) = 0.
CHAPTER 5 Mixers
Published in Douglas Self, Audio Engineering Explained, 2012
Professional-quality microphones have an output impedance of around 200 ohms, and the balanced microphone inputs will have an input impedance of between 1000 and 2000 ohms (“2 kΩ”, k = thousand). The outputs should have an impedance of around 200 ohms or lower. The headphone output impedance will typically be 100 ohms or so. Small mixers usually have a separate power supply which plugs into the mains. This typically contains a mains transformer, rectifiers and regulating circuitry, and it supplies the mixer with relatively low DC voltages. The main advantage of a separate power supply is that the mains transformer can be sited well away from the mixer, since the alternating 50 Hz mains field around the former can be induced into the audio circuits. This manifests itself as “mains hum” which is only really effectively dealt with by increasing the distance between the mixer and the transformer. Large mixers usually have separate rack-mounting power supplies.
Design and Analysis of 30 GHz CMOS Low-Noise Amplifier for 5G Communication Applications
Published in IETE Journal of Research, 2023
K. Dineshkumar, Gnanou Florence Sudha
For stage-I, the CS-CG amplifier cascode configuration is used. The common gate transistor increases the input-output reverse isolation, gain and also stability of the amplifier. The noise figure mainly falls on gate-width and transconductance of the transistor, hence the transistor is liable for the noise figure. So, the noise figure is minimized by reducing the gate width of the transistor. Also, the noise-matching capacitor that is deployed in stage-I suppresses the noise of the circuit. To overlook the parasitic capacitance , , and are used an inductor is added to the common source structure to achieve inductive source degeneration. Moreover, the transconductance and drain-to-source resistance of the transistor enhance the output impedance.
A novel design procedure of a compact-size X-band shunt feedback amplifier
Published in International Journal of Electronics, 2023
Hafiz Hejazi, Majid Baghaei Nejad
K, T, and RS are the Boltzmann constant, temperature, and source impedance, respectively. Moreover , and are the output short circuit currents. Mentioned currents are due to the transistor gate and drain, respectively. Also, gm is the transconductance of the transistor, and Ro is the output impedance at the drain node. For simplification, the effects of Tline and drain-source impedance of the transistor are neglected. To minimise the NF, the RFN and CFN values must approach infinity and zero, respectively. Figure 6 depicts NF contours in the mid-band frequency. NF is minimised at the right top, right bottom, and left below of the plots, as expected.
A compact time-to-amplitude converter for single-photon time-of-flight measurement
Published in Journal of Modern Optics, 2021
Zhiqiang Ma, Yue Xu, Sihui Zhu, Zhong Wu
The operating principle of the TAC is very straight-forward. Figure 2 shows the timing diagram of each key node of the circuit during the d-TOF measurement process. In the initial stage, the reset signal ‘Rst’ is valid, and the transistors MN5 and MP8 are turned on to discharge the timing capacitor C. Then the pulsed laser emission generates the ‘Start’ signal to trigger the TAC conversion, and the TOF measurement starts on the rising edge of the ‘Start’ signal. At this time, the current source of regulated cascode structure outputs a stable current to charge the timing capacitor, and the voltage amplitude on the timing capacitor increases linearly with time. With the arrival of the ‘Stop’ signal, the conversion process ends, and the ‘Stop’ signal is generated by the echo photon triggering signal. The output voltage ΔVc on the timing capacitor can be approximately expressed by where (W/L)X is the channel-width-to-length ratios of transistor X. The output impedance Rout of the current mirror can be expressed as where, gm,X and ro,X are the transconductance and output impedance of the transistor X, respectively. Observing equations (1) and (2), it can be found that the current source has a very high output impedance, thus ensuring the stability of the output current. The output voltage linearity is mainly related to the stability of the input current Ibias.