| 摘要 |
<p>A cellular telephone comprises a direct conversion receiver circuit (14) using even-harmonic quadrature mixer (24), and high-pass filters (56, 58, 64, 66) for removing DC offset components before and behind variable-gain amplifiers (60, 62) in a baseband circuit (30). The DC components appearing in the even-harmonic quadrature mixer (24) is constant, while the DC components appearing in the variable-gain amplifiers (60, 62) change with time. Therefore, the cutoff frequency of the high-pass filters (64, 66) in the back stage is set higher than the cutoff frequency (fc1) of the high-pass filters (56, 58) in the front stage so that the transient response may be fast.</p> |
