In FIG. 28, another embodiment comprises an amplifier wherein a local feedback circuit includes Q3 with Q6 and or includes Q5 with Q7. An first input signal is coupled to the base of Q1 and or Q2. Q5 provides a DC current with optionally enabling a second input signal, Vopt, that is coupled to the base or emitter of Q5. Gain control is provided by varying control voltage V6 and or V7, which will affect the amount of local feedback to the emitter of Q1 and or Q2. The amount of local feedback to the emitter of Q1 and or Q2 will provide a predetermined gain and or provide a predetermined distortion characteristic. In this embodiment example, one or more amplifiers, A1, A2, A3, A4, A5, and or A6 may be included (e.g., as shown in FIG. 28).
FIG. 29 shows an adjustable Vbe multiplier (e.g., biasing) circuit comprising Q3 and Q6, wherein the voltage is provided across the collector and emitter of Q3. Amplifiers, A1, A2, and or A6 are optional. For example, if any amplifier A1, A2, and or A6 is removed, a coupling element (e.g., a wire or resistor) may be connected between the original input and output terminal of each amplifier that is removed. For example, if A6 (e.g., wherein A6 has input terminal i6 and output terminalo06) is removed, a wire or coupling element is connected/coupled from the junction of R6 (e.g., via i6) and drain of Q6 to the base of Q3 (e.g., via o6).
