| 摘要 |
<p>An enhanced delta modulation encoder (10) includes a spectrum tilter (24), a 1 bit analog-to-digital converter (26), a sampling circuit (28) and an internal decoder (22). An analog input signal and an internal analog signal from the internal decoder (22) are summed to provide an analog dither signal. The analog dither signal is tilted by the spectrum tilter (24) and is provided to the 1 bit analog-to-digital converter (26) which generates a digital signal. The sampling circuit (22) receives the digital signal from the analog-to-digital converter (26) and generates a digital output which is fed back to the internal decoder (22). The spectrum tilter (24) comprises at least three integrator circuits (38, 56, 58) and a clipping circuit (36). The three integrator circuits (38, 56, 58) tilt the frequency spectrum of noise above the maximum frequency of interest, the clipping circuit (36) prevents the encoder from becoming unstable.</p> |
