| 摘要 |
A Class D amplifier having a low level audio signal feeding the negative input of an Integrator via an input resistor. Said Integrator feeds a Comparator having well-defined Hysterisis. Said Comparator output is connected to a First Level Shifter in order to convert a ground-referenced signal to a negative-voltage-rail-referenced signal so as to provide a drive signal for a First Switching Device which is connected to a Negative Rail Voltage (Vminus) and an Output, where said Output is defined as the junction of said First and a Second Switching Device and said junction having a time averaged signal of high power capable of driving a low impedance load such as a loudspeaker . A Second Level Shifter is provided so as to drive said Second Switching Device which is connected to the Positive Rail Voltage (Vplus) and said Output. The signal from said Second Level Shifter is floating and referenced to said Output. The signal at said Output is kept in phase with the signal of said Second Level Shifter, yielding very high .DELTA.v/.DELTA.t immunity at said Output. A Feedback Resistor is provided from said Output to the negative input of said Integrator in order to ensure self oscillation and to provide negative feedback in order to reduce distortion and the effective output impedance (increasing the damping factor). A Low-Pass filter between said Output and said Load is desirable to reduce unwanted RF and switching noise. BACKGROUND The present invention is related in general to high efficiency power amplification. In particular, it is related to the Class D type switching amplifier wherein voltage and current stresses are never simultaneously present, yielding efficiencies in the 90%+ region. The present invention achieves this objective with the minimum number of inexpensive "off the shelf " components while maintaining a high degree of functionality and reliability.
|
