Search results
Results from the WOW.Com Content Network
If the voltage is transferred unchanged (the voltage gain A v is 1), the amplifier is a unity gain buffer; also known as a voltage follower because the output voltage follows or tracks the input voltage. Although the voltage gain of a voltage buffer amplifier may be (approximately) unity, it usually provides considerable current gain and thus ...
A circuit diagram of a buffer amplifier made using an operational amplifier. = = (realistically, the differential input impedance of the op-amp itself, 1 MΩ to 1 TΩ) Date: 26 January 2009: Source: Own work
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 ...
Figure 2: A unity-gain low-pass filter implemented with a Sallen–Key topology. An example of a unity-gain low-pass configuration is shown in Figure 2. An operational amplifier is used as the buffer here, although an emitter follower is also effective. This circuit is equivalent to the generic case above with
Nonetheless, the voltage gain is appreciable even for small loads: according to the table, with R S = r E the gain is A v = g m R L / 2. For larger source impedances, the gain is determined by the resistor ratio R L / R S, and not by the transistor properties, which can be an advantage where insensitivity to temperature or transistor variations ...
As the output voltage increases more, Q2 will saturate, so the circuit's gain is again reduced by the additional inclusion of R6 into the parallel feedback resistance. Temperature-compensation transistors Q4 and Q1 cancel out the temperature-dependent p–n junction base-emitter forward voltage drop of Q3 and Q2. Additional linear segments can ...
Thus this circuit finds applications as a voltage buffer. In other words, the circuit has current gain (which depends largely on the h FE of the transistor) instead of voltage gain. A small change to the input current results in much larger change in the output current supplied to the output load.
as long as the loop gain : is much greater than unity. Fig. 4. Bode plot of uncompensated transimpedance amplifier [5] In the Bode plot of a transimpedance amplifier with no compensation, the flat curve with the peak, labeled I-to-V gain, is the frequency response of the transimpedance amplifier. The peaking of the gain curve is typical of ...