Look-ahead delta sigma modulator having an infinite impulse response filter with multiple look-ahead outputs
First Claim
1. A method of processing a signal using a multiple output infinite impulse response (“
- IIR”
) filter of a look-ahead delta-sigma modulator, the method comprising;
determining a set of state variables for respective stages of the IIR filter for a time t from a set of input signals, wherein at least a subset of the state variables of the respective stages of the IIR filter represent a current response and at least one future response element of a natural response vector of the IIR filter, wherein t represents a time index value; and
determining a quantization output of the look-ahead delta sigma modulator for the time t using the natural response vector determined for the time t.
1 Assignment
0 Petitions
Accused Products
Abstract
A delta sigma modulator look-ahead IIR filter response can be divided into a natural response and a pattern response using superposition techniques. The look-ahead delta sigma modulators of the signal processing systems described herein include an infinite impulse response filter (“IIR”) that produces multiple output look-ahead natural responses to input signals having a look-ahead depth of “M”. The multiple output lookahead IIR filter reduces the amount of processing and memory used by the delta sigma modulator to generate quantizer output values. The multiple output lookahead IIR filter uses extended delay stages and modified feedback coefficients to concurrently produce multiple look-ahead natural responses. In one embodiment, the multiple output lookahead IIR filter concurrently produces M look-ahead natural responses.
-
Citations
29 Claims
-
1. A method of processing a signal using a multiple output infinite impulse response (“
- IIR”
) filter of a look-ahead delta-sigma modulator, the method comprising;determining a set of state variables for respective stages of the IIR filter for a time t from a set of input signals, wherein at least a subset of the state variables of the respective stages of the IIR filter represent a current response and at least one future response element of a natural response vector of the IIR filter, wherein t represents a time index value; and determining a quantization output of the look-ahead delta sigma modulator for the time t using the natural response vector determined for the time t. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- IIR”
-
13. A method of processing a signal using a multiple output infinite impulse response (“
- IIR”
) filter of a look-ahead delta-sigma modulator, the method comprising;updating a set of state variables of the IIR filter; conducting a memory-less operation to determine elements of a natural response vector using the updated set of state variables, wherein the elements of the natural response vector include a current response output and at least one future response output of the IIR filter to a set of input signal samples; and determining a quantization output of the look-ahead delta sigma modulator for time t using the natural response outputs. - View Dependent Claims (14, 15)
- IIR”
-
16. A signal processing system comprising:
a look-ahead delta sigma modulator having a depth of M, the look-ahead delta sigma modulator comprising; an infinite impulse response (IIR) loop filter to filter a set of input signal samples, the IIR loop filter having K natural response outputs for each of K elements of a natural response vector SNATt for each time t, wherein at least one output is for a future output and 1<
K≦
M, wherein K and M are integers; anda quantizer to determine a quantization output for each time t using the natural response vector SNATt. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
28. An apparatus for processing a signal using a multiple output infinite impulse response (“
- IIR”
) filter of a look-ahead delta-sigma modulator, the apparatus comprising;means for determining a set of state variables for respective stages of the IIR filter for a time t from a set of input signals, wherein at least a subset of the state variables of the respective stages of the IIR filter represent a current response and at least one future response element of a natural response vector of the IIR filter, wherein t represents a time index value; and means for determining a quantization output of the look-ahead delta sigma modulator for the time t using the natural response vector determined for the time t.
- IIR”
-
29. A method of determining feedback coefficients for a multiple output, L-order, infinite impulse response (“
- IIR”
) filter of a look-ahead delta-sigma modulator of depth M, wherein the IIR filter includes a plurality of state variables and M is an integer greater than one, the method comprising;determining feedback coefficients for the IIR filter from the state variables using (i) an at least approximately zero input, (ii) feedback coefficients setting a characteristic of the IIR filter without K−
1 natural response delay stages, wherein 1<
K≦
M, and (iii) an impulse function forced feedback response followed by L−
1 at least approximately zeros, wherein the feedback coefficients for the IIR filter comprise state variables of each of the initial stages and the K−
1 natural response delay stages after completion of the impulse function and L−
1 zeros, wherein K and L are integers.
- IIR”
Specification