| 摘要 |
<p>A pulse-width-modulated digital-to-analog converter (10) is responsive to a digital control value (35) for switching between a high gain mode and a low gain mode. The converter includes a free-running rollover counter (45), a reference register (55) and a comparator (60). Pulses from a comparator are split into two paths, one path including a switch (20), and fed into a plurality of resistive elements connected to a common output node (91). Depending on the state of the switch, the network's output value will either follow its input or be a fraction thereof, without change of duty cycle or output impedance. The output node may be connected to a capacitive element (C1) to form a low pass filter for generating an analog waveform.</p> |
