Patent ID: 7426377
Filing Date: 2008-09-16
Classification: H04B

Abstract:
1. A sigma delta transmitter to selectively output one output signal out of a plurality of output signals of a signal transmitting circuit which includes a buffer or a divider having a constant dividing ratio and to which an output of a first voltage controlled oscillator is connected, said sigma delta transmitter comprising: a first phase comparator; a first charge pump; a first loop filter; a first digital frequency limiter; a first interpolator; first and second data registers; a first adder having the output of said first interpolator connected to its first input and the output of said first data register connected to its second input; a first sigma delta converter, the output of said first adder being connected to an input thereof; a second adder having the output of said first sigma delta converter connected to its first input and the output of said second data register connected to its second input; a first variable divider, the output of said first voltage controlled oscillator is connected to an input thereof; a first variable counter to which the output of said first variable divider is inputted; and a second variable counter to which the output of said first variable divider is inputted, wherein the output of said first variable counter is connected to the dividing factor switching terminal of said first variable divider, wherein a superior digit of the output of said second adder is connected to the initial value setting terminal of said first variable counter and an inferior digit of the same is connected to the initial value setting terminal of said second variable counter, wherein the output of said second variable counter is connected to the first input of said first phase comparator, wherein the output of said first phase comparator is connected to the input of said first charge pump, wherein the output of said first charge pump is connected to the input of said first loop filter, and wherein the output of said first loop filter is connected to the control voltage input terminal of said first voltage controlled oscillator.