Title: Radio transmitter architecture comprising PLL and delta-sigma modulator
Application Number: 00814432 Application Date: 2000.09.21
Publication Number: 1387717 Publication Date: 2002.12.25
Approval Pub. Date: 2005.02.23 Granted Pub. Date: 2005.02.23
International Classifi-cation: H03C3/09;H04L27/20
Applicant(s) Name: Cadence Design Systems Inc. Address:
Inventor(s) Name: Martin Wilson
Attorney & Agent: han hong
Abstract:
    The transmitter circuit architecture is disclosed based on a phase lock loop architecture and which uses a delta-sigma modulator with 2 point modulation. In order to restrict the bandwidth of the PLL, subsidiary analogue modulation is employed, which requires aligning with the delta-sigma modulation. Alignment of the modulation is accomplished by correction of the sensitivity of the PLL voltage controlled oscillator to modulation by correlating residual modulation in the PLL with the modulated signal input. The action of the modulation correlator trims the modulation and the PLL bandwidth without disturbing the normal operation of the transmitter, and allows the use of modulation bandwidths greater than the PLL bandwidth.
Time: 12