Method and apparatus for a/d conversion

Abstract

A method and an apparatus for converting an analog input signal into a digital output signal using a sigma-delta modulator architecture with a digital tracking filter. The digital tracking filter may have an order greater than one, and the signal and noise transfer functions of the sigma-delta modulator architecture are chosen to provide a sigma-delta modulator architecture with a high dynamic range even if a relatively low oversampling ratio is used.

1 . A method for converting an analog input signal to a digital output signal, the method comprising:
 filtering a quantized difference signal with a filter function having a second order or third order filter function to obtain a digital estimate signal of the analog input signal; and   converting the digital estimate signal to the analog estimate signal.   
   
   
       2 . The method according to  claim 1 , wherein the digital estimate signal is quantized by a quantizer before converting it into the analog estimate signal. 
   
   
       3 . The method of  claim 1 , wherein the difference signal is quantized using a quantizer having a resolution of up to six bits to obtain the quantized different signal. 
   
   
       4 . An apparatus configured to convert an analog input signal to a digital output signal, the apparatus comprising:
 a filer having a second order or third order filter function, the filter configured to obtain a digital estimate signal of the analog input signal; and   a digital/analog converter configured to convert the digital estimate signal into an analog estimate signal.   
   
   
       5 . The apparatus according to  claim 4 , wherein a quantizer is provided between the filter and an adder which is configured to form a difference signal. 
   
   
       6 . The apparatus according to  claim 5 , wherein the quantizer has a resolution of up to six bits.