experiment 5
OBJECTIVES
To demonstrate the effects that a bypass capacitor has on amplifier voltage gain (Av).
To demonstrate the ac operation of the common-emitter (CE) amplifier.
INTRODUCTION
A common emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both. The input signal to a CE amplifier is applied across the base-emitter junction of the device. The output from this circuit is taken from the collector terminal of the transistor. Since the emitter is connected to the ground, it is common to signals, input and output. The CE amplifier is one of the most commonly used BIT amplifier configurations.
The amplifier has a relatively high voltage gain, a relatively high current gain, and a voltage phase shift of 180° between its input (base) and output (collector) terminals. Common emitter amplifiers give the amplifier an inverted output and can have a very high gain that may vary widely from one transistor to the next. The gain is a strong function of both temperature and bias current, and so the actual gain is somewhat unpredictable. Stability is another problem associated with such high gain circuits due to any unintentional positive feedback that may be present.
The bandwidth of the common-emitter amplifier tends to be low due to high capacitance resulting from the Miller effect. The parasitic base-collector capacitance appears like a larger parasitic capacitor (where the voltage gain is negative) from the base to ground. This large capacitor greatly decreases the bandwidth of the amplifier.
The common- emitter circuit is the most widely used of junction, transistor amplifiers. As compared with the common- base connection, it has higher input impedance and lower output impedance. A single power supply is easily used for biasing. In
To demonstrate the effects that a bypass capacitor has on amplifier voltage gain (Av).
To demonstrate the ac operation of the common-emitter (CE) amplifier.
INTRODUCTION
A common emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both. The input signal to a CE amplifier is applied across the base-emitter junction of the device. The output from this circuit is taken from the collector terminal of the transistor. Since the emitter is connected to the ground, it is common to signals, input and output. The CE amplifier is one of the most commonly used BIT amplifier configurations.
The amplifier has a relatively high voltage gain, a relatively high current gain, and a voltage phase shift of 180° between its input (base) and output (collector) terminals. Common emitter amplifiers give the amplifier an inverted output and can have a very high gain that may vary widely from one transistor to the next. The gain is a strong function of both temperature and bias current, and so the actual gain is somewhat unpredictable. Stability is another problem associated with such high gain circuits due to any unintentional positive feedback that may be present.
The bandwidth of the common-emitter amplifier tends to be low due to high capacitance resulting from the Miller effect. The parasitic base-collector capacitance appears like a larger parasitic capacitor (where the voltage gain is negative) from the base to ground. This large capacitor greatly decreases the bandwidth of the amplifier.
The common- emitter circuit is the most widely used of junction, transistor amplifiers. As compared with the common- base connection, it has higher input impedance and lower output impedance. A single power supply is easily used for biasing. In