Quadrature sampling architecture and method for analog-to-digital converters
First Claim
1. A system for quadrature sampling input signals to produce complex digital data output signals, comprising:
- sampling circuitry coupled to an input signal and having real and imaginary sampled output signals;
analog-to-digital converter circuitry coupled to the real and imaginary sampled output signals and having real and imaginary digital data output signals; and
filter circuitry coupled to the real and imaginary digital data output signals to provide a relative delay between the real and imaginary digital data output signals of one-fourth cycle.
1 Assignment
0 Petitions
Accused Products
Abstract
Quadrature sampling architecture and method are disclosed for analog-to-digital converters that provide improved digital output signals over prior quadrature mixing implementations. Sampling circuitry according to the present invention samples an input signal with a first and second sampling signals to produce real and imaginary sampled output signals. The first sampling signal, which is associated with the real sampled output signal, is delayed by one-fourth cycle with respect to the second sampling signal, which is associated with the imaginary sampled output signal. This one-fourth cycle sampling signal difference allows for simplified construction of the sampling circuitry. In addition, filter circuitry according to the present invention processes the real and imaginary digital data output signals so that the imaginary digital data output signal is advanced by one-fourth cycle with respect to the real digital data output signal. This one-fourth cycle relative advance tends to eliminate undesirable magnitude distortion and error signals in complex digital output signals that have been mixed down to baseband. Furthermore, the real and imaginary signal paths may be interchanged and still take advantage of the present invention.
48 Citations
22 Claims
-
1. A system for quadrature sampling input signals to produce complex digital data output signals, comprising:
-
sampling circuitry coupled to an input signal and having real and imaginary sampled output signals;
analog-to-digital converter circuitry coupled to the real and imaginary sampled output signals and having real and imaginary digital data output signals; and
filter circuitry coupled to the real and imaginary digital data output signals to provide a relative delay between the real and imaginary digital data output signals of one-fourth cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. Quadrature sampling circuitry, comprising:
-
real path sampling circuitry coupled to an input signal and being controlled by a first sampling signal; and
imaginary path sampling circuitry coupled to the input signal and being controlled by a second sampling signal, wherein the first sampling signal and the second sampling signal have a relative delay between them of one-fourth cycle. - View Dependent Claims (13, 14, 15, 16)
-
-
17. A method for quadrature sampling of input signals to produce complex digital data output signals, comprising:
-
receiving an input signal;
sampling the input signal to produce a real sampled signal and an imaginary sampled signal;
converting the real and imaginary sampled signals to real and imaginary digital data output signals; and
processing the real and imaginary digital data output signals to provide a relative delay between the real and imaginary digital data output signals of one-fourth cycle. - View Dependent Claims (18, 19, 20, 21, 22)
-
Specification