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Thus a current mirror consists of two cascaded equal converters (the first – reversed and the second – direct). Figure 1: A current mirror implemented with n–p–n bipolar transistors using a resistor to set the reference current I REF; V CC is a positive voltage.
A modified version of the cascode can also be used as a modulator, particularly for amplitude modulation. The upper device supplies the audio signal, and the lower is the RF amplifier device. High-voltage stack. A cascode may also be combined with a voltage ladder to form a high-voltage transistor.
Fig. 1: Wilson current mirror Fig. 2: Wilson current source. There are three principal metrics of how well a current mirror will perform as part of a larger circuit. The first measure is the static error, i.e., the difference between the input and output currents expressed as a fraction of the input current.
Another major drawback is the amplifier's limited high-frequency response. Therefore, in practice the output often is routed through either a voltage follower (common-drain or CD stage), or a current follower (common-gate or CG stage), to obtain more favorable output and frequency characteristics. The CS–CG combination is called a cascode ...
List of free analog and digital electronic circuit simulators, available for Windows, macOS, Linux, and comparing against UC Berkeley SPICE.The following table is split into two groups based on whether it has a graphical visual interface or not.
The current gain is unity, so the same current is delivered to the output load R L, producing by Ohm's law an output voltage v out = v Thév R L / R S, that is, the first form of the voltage gain above. In the second case R S << 1/g m and the Thévenin representation of the source is useful, producing the second form for the gain, typical of ...
At the same time, the input voltage source V 1 and the current-setting resistor R form a composed current-source that "want" to produce a current I IN = V 1 /R through a voltage-stable element (the transistor T 1). By the way, some mystic cascode circuits are based on the same arrangement (a current source supplies a voltage-stable element and ...
The emitter junctions of these amplifier stages are fed by the collectors of a third differential pair (Q2/Q6). The output currents of Q2/Q6 become emitter currents for the differential amplifiers. Simplified, the output current of an individual transistor is given by i c = g m v be. Its transconductance g m is (at T = 300 K) about g m = 40 I C.