| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide the structure for a low noise amplifier that has a high input impedance and a high input common mode rejection ratio. SOLUTION: An input signal Vin is fed to terminals N2, P1 of a differential amplifier DDA1 having differential output terminals output, and two pairs of differential input terminals N1, P1; N2, P2. Since there is no differential amplifier pair that receives a high input signal level and no differential amplifier pair that generates unacceptable harmonic distortion, an input dynamic range is high. The remaining terminals are used for the operation in the common rejection mode which is independent of the output common rejection mode and receive a bias signal via a common mode feedback circuit (DDA2; GL1, GH1, GH3, R2a, R2a'; GL2, GH2, GH4, R2b, R2b') receiving an output of a 2nd differential amplifier DDA2, and switching elements (GL1, GH1, GH3, GL2, GH2, GH4) are used to program the gain of the differential amplifier DDA2.</p> |
