Hybrid DAC suitable for use in a GPS receiver
US5764172A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 5, 1996 |
| Grant date | Jun 9, 1998 |
| Priority date | — |
| Expiry date | Apr 5, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/68
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus including a hybrid digital-to-analog converter (DAC) (10) for converting a combined digital word (23) into a combined analog output level (21) and a GPS receiver (36) for providing the combined digital word (23) and using the combined analog output level (21) for phase locking a voltage controlled oscillator (VCO) (40) to a GPS satellite signal (34). The combined digital word (23) includes a more significant (MS) digital word (13) having N bits and a less significant (LS) digital word (15) having M bits. The hybrid DAC (10) includes a pulse generator DAC (12) for converting the MS digital word (13) into pulse output signal having a duty cycle and an average MS analog level representative of the MS digital word (13) and a second DAC (14) for converting the LS digital word (15) into an average LS analog level representative of the LS digital word (15). The pulse generator DAC (12) uses a counting technique in order to obtain a high degree of precision. A filter/combiner (18) filters and combines the average MS and the LS analog levels into a combined analog output level (21) representative of the combined digital word (21) to control the VCO (40) for providing a GPS-deri…
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