Patent ID: 7324798

Claim:
An I/Q frequency modulator for a direct conversion transmitter, comprising: an I/Q input unit receiving In-phase (I) and Quadrature-phase (Q) component signals; an I switching unit receiving and modulating sub-harmonic signals with a frequency of F TX /2 N and 2 N+1 phases, where N is a natural number equal to or greater than 1, and the I component signals and outputting a signal with a frequency of F TX ; a Q switching unit receiving and modulating the sub-harmonic signals and the Q component signals and outputting a signal with a frequency of F TX ; a load unit functioning as a load; and an output unit providing output signals of the I and Q switching units as Radio Frequency (RF) signals, wherein the I switching unit includes a first and a second switching components, each comprised of 2 N transistor pairs, the first switching component having each transistor pair that receives signals with phases expressed by [0+180/2 N *(i−1), 180+180/2 N *(i−1)], where i is a natural number ranging from 1 to 2 N , the second switching component having each transistor pair that receives signals with phases expressed by [180/2 N −180/2 N *(i−1), 180+180/2 N −180/2 N * (i−1)], where i is a natural number ranging from 1 to 2 N , and wherein the Q switching unit includes a third and a fourth switching components, each comprised of 2 N transistor pairs, the third switching component having each transistor pair that receives signals with phases expressed by [90+180/2 N *(i−1), 270+180/2 N *(i−1)], where i is a natural number ranging from 1 to 2 N , the fourth switching component having each transistor pair that receives signals with phases expressed by [90+180/2 N −180/2 N *(i−1), 270+180/2 N 180/2 N * (i−1)], where i is a natural number ranging from 1 to 2 N .