Common-emitter transistor amplifier quiescent bias circuit diagram

Posted on Mar 28, 2007

Common-emitter amplifier V502, V504, V506 emitter static potential bias voltage forming circuit [ie voltage follower) shown in Figure 3. Active filter by the V507, VD502, VD503

Common-emitter transistor amplifier quiescent bias circuit diagram
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, R534, R535, C514, R540 is composed of V502, V504, V506 emitter static bias voltage follower circuit. R535, R534 composed divider network dividing point voltage by 1.85V down to V507 VD502 VD503 string base, about 0.7V, its emitter voltage of about 1.35V or so, as the common-emitter amplifier V502, V504, V506 three only enlarge the emitter bias voltage source tube. Common base amplifier base bias voltage directly from + 9V power supply, common base amplifier tube base by C513 AC ground, and therefore input and output signals in terms of V501, V503, V505 for the common-base circuit. Using V507 (PNP-tube) as a common-emitter amplifier video amplifier quiescent bias in the emitter voltage follower, because the video amplifier common base amplifier tubes V501, V503, V505 are connected to the base of the power supply + 9V endpoint. A slight change in the supply voltage, will affect its quiescent operating point, the output tube collector static potential changes affecting the brightness of the screen. For this reason, the use of the circuit diagram, so that common-emitter amplifier bias voltage emitter follower + 9V power supply trace changes synchronously change, that a slight change in the + 9V power supply, V502, V504, V506 emitter voltage follower change, to ensure total emitter, common base of two transistors are not fluctuate with changes in the power trace, ie V501, V503, V505 collector static potential unchanged. This aspect can ensure consistency of product performance in large quantities, but also to ensure that single brightness is not affected by small changes in the supply voltage. VD503, VD502 junction voltage (0.5-0.7V) decreases with increasing temperature, so that V507 emitter potential rise can be compensated video amplifier common emitter, increased two cascaded amplifiers Shenlian common base transistor with increasing temperature, causing static IMPACT operating point changes, so that the final stage amplifier video amplifier drift is reduced, job stability is greatly improved. Since the C514 is connected between the power supply + 9V and V507 base, but also to avoid power transients caused by luminance transients.

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