Variable, adaptive quantization in sigma-delta modualtors

摘要

An improved sigma-delta modulation technique that may be employed in a sigma-delta Digital-to-Analog Converter (DAC) to convert digital signals into corresponding analog signals over a wide signal range and with high linearity. The sigma-delta DAC (200) comprises a sigma-delta modulator (201) including a variable quantizer (204) and a quantizer controller (218), and an internal DAC (206). The sigma-delta modulator (201) adaptively quantizes the digital input signal to a first number p of quantization levels. Next, the quantizer controller (218) controls the variable quantizer (204) to correlate the p quantization levels to the amplitude of the digital input signal, thereby generating a second number q of quantization levels. The internal DAC (206) then receives the q quantization levels from the variable quantizer one group of p levels at a time, and produces an analog output signal therefrom that corresponds to the digital input signal.