Bandpass sigma delta converter suitable for multiple protocols
US5345406A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1992 |
| Grant date | Sep 6, 1994 |
| Priority date | — |
| Expiry date | Aug 25, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/418
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Improved integration and simplified construction of direct conversion receivers is achieved by providing selectivity in the early stages of a sigma delta converter to reject adjacent channel signals and thereby allow greater dynamic range for the desired input signals. A bandpass sigma delta converter is taught which is suitable for use with signals having multiple protocols. In a first stage, an aliased input signal is applied to two filters having desired and preferably programmable filter characteristics which provide selectivity to the input signal. A third filter is utilized having a programmable center frequency, which receives as an input signal the sum of the filtered input signal plus the quantization noise of the first stage. This provides a first intermediate output signal of desired selectivity. Quantization noise of the first stage is also applied to a second filter stage which provides a second intermediate output signal having a first component related to the quantization noise of the first stage, and a second component which is the shaped quantization noise of the second stage. The first and second intermediate output signals are combined in order to provide a desir…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.