Thus, for a current sense amplifier, it is an important parameter as it will reflect the very low common-mode signal across the output, thus creating the possibilities to open up a wide range of current sensing capabilities. Current sense amplifiers have high CMRR and it could sense small common-mode signals.
CMRR is also responsible for reducing noise on the current sense lines. Suppose a design with a 12V 1A line, where a high current sensing circuit needs to be used. In such a case, a current sense circuit can be built using current sense amplifiers. But before proceeding with the circuit, one needs to select a current sense amplifier for this purpose.
Since the maximum current rating is 1A, and no specified load is described, a current sense amplifier needs to be selected that works with 12V supply and could sense more than the 1A of the current rating. As discussed, one needs to select something for the low-level side or high-level side.
In this case, a high side current sensing can be used for detecting a fault or proper short circuit condition. However, low side current sensing can also work. We will discuss the difference between these both later in this article. Since the load could be capacitive or inductive, inrush current could occur, thus a low-value resistor can be used with a dedicated current sense amplifier. For this circuit, LT can be used since it works with 2. Therefore, this amplifier could work in 12V supply as well as it could detect very low current flow.
The above current sense amplifier circuit is build using LT The 0. In the above circuit, a trip point is created across mA. However, for a trip voltage above 1A, the targeted value can be set by the voltage divider across the INC pin of the current sense amplifier. The Vout at OUTA pin of the current sense amplifier can be used to check the current flow rating through the current sense resistor.
The above circuit can also be constructed using another current sense amplifier that uses a wide range of supply voltage more than 12V and could accept the input irrespective of the supply voltage. As discussed previously, a shunt resistor is used to sense the current, and depending on the shunt resistor placement, the current sense technique varies.
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Texas Instruments has been making progress possible for decades. The load resistance is capacitor coupled to the emitter terminal of the transistor. When a signal is applied to the base of the transistor ,VB is increased and decreased as the signal goes positive and negative, respectively.
Since the emitter is output terminal, it can be noted that the output voltage from a common collector circuit is the same as its input voltage. Hence the common collector circuit is also known as an emitter follower. Keeping the input voltage constant, vary the frequency from 0 Hz to 1M Hz in regular steps and note down the corresponding output voltage. Result: Thus, the Common collector amplifier was constructed and the frequency response curve is plotted.
Capacitor 1. Function Generator MHz 2 6. For good bias stability, the source resistor voltage drop should be as large as possible. Where the supply voltage is small, Vs may be reduced to a minimum to allow for the minimum level of Vds. Generally to have high input impedance FET is used. Observe the output on CRO for proper working of the amplifier. Calculate gain in dB and plot on semi log graph paper for frequency Vs gain in dB.
Regulated power supply V 1 7. Bread Board 1 Theory: In Darlington connection of transistors, emitter of the first transistor is directly connected to the base of the second transistor. Due to very large amplification factor even two stage Darlington connection has large output current and output stage may have to be a power stage.
As the power amplifiers are not used in the amplifier circuits it is not possible to use more than two transistors in the Darlington connection.
In Darlington transistor connection, the leakage current of the first transistor is amplified by the second transistor and overall leakage current may be high, which is not desired. Plot the graph; Gain dB vs Frequency Hz. Calculate the bandwidth from the graph. Result: Thus, the Darlington current amplifier was constructed and the frequency response curve is plotted.
Transistor BC 2 2. Resistor 4. Regulated power supply V 1 4. Function Generator MHz 2 5. CRO 30 MHz 1 6. Bread Board 1 Theory: The differential amplifier is a basic stage of an integrated operational amplifier. It is used to amplify the difference between 2 signals. It has excellent stability, high versatility and immunity to noise.
In a practical differential amplifier, the output depends not only upon the difference of the 2 signals but also depends upon the common mode signal. Transistor Q1 and Q2 have matched characteristics. The values of RC1 and RC2 are equal. Re1 and Re2 are also equal and this differential amplifier is called emitter coupled differential amplifier.
The output is taken between the two output terminals. Connections are given as per the circuit diagram. To determine the differential mode gain, we set input signals with voltages V1 and V2. Measure the dc collector current for the individual transistors. Result: Thus, the Differential amplifier was constructed and dc collector current for the individual transistors is determined. Theory: The differential amplifier is a basic stage of an integrated operational amplifier.
For the differential mode operation the input is taken from two different sources and the common mode operation the applied signals are taken from the same source Common Mode Rejection Ratio CMRR is an important parameter of the differential amplifier.
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