| 摘要 |
<p>Described herein is a direct digital radio frequency modulator (1010) in which out of band quantisation noise is filtered directly at radio frequency. The modulator (1010) comprises a plurality of modulator elements (1012, 1014, 1016, 1018) each having a voltage bias transistor (1050). The transistor (1050) is tuned in accordance with finite impulse response filter coefficients. A pair of switches (EN0(1), RFin0, EN90(1), RFin90, EN180(1), RFin180, EN270(1), RFin270) is provided for each input phase. The RF signals are spaced apart from one another in accordance with a duty cycle related to the number of input phases.</p> |
