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Polar implementation of a universal direct conversion D-S modulator transmitter architecture supporting digital data transmission

IP.com Disclosure Number: IPCOM000010416D
Publication Date: 2002-Nov-27
Document File: 3 page(s) / 169K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a polar implementation of a universal direct conversion sigma-delta (D-S) modulator transmitter architecture supporting digital data transmission. Benefits include improved performance, improved functionality, and improved design simplicity.

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Disclosed is a polar implementation of a universal direct conversion sigma-delta (D-S) modulator transmitter architecture supporting digital data transmission. Benefits include improved performance, improved functionality, and improved design simplicity.

General description

        � � � � � The disclosed method is a universal transmitter architecture supporting digital data transmission. Linear amplification using nonlinear components (LINC) is combined with direct modulation through fractional-N synthesizers. With a D-S modulator, the density of appearance of +1 and –1 is set according to an input DC value related to the desired transmit frequency. A fractional-N synthesizer has built-in data modulation for continuous phase modulation, such as CPFSK and GMSK. The transmitted signal can be expressed in an equation (see Figure 1). This equation contains the following values:
•        � � � � Ac - Transmitted amplitude

•        � � � � wc - Transmitted frequency

•        � � � � Df� - Deviation index

•        � � � � m(t) - Baseband digital signal

        � � � � � The phase of s(t) is proportional to the integral of m(t). In a direct modulation synthesizer the integral of the signal is performed by the VCO. The use of a D-S modulator improves the synthesizer performance because the quantization noise power spectral density grows with the frequency. It is very s...