| 摘要 |
<p>In a balanced differential amplifier, a constant current source MOS FET operable in an unsaturated region is usually incorporated. When noise is inputted to the differential amplifier, the current source MOS FET undergoes an influence of noise level superposed upon the input signal DC voltage thereof, thus deteriorating the constant current characteristics. To overcome this problem, a pair of current source MOS FETs (35, 45) are additionally incorporated therewith. Since the two current source MOS FETs (35, 45) operate near a boundary between saturated and unsaturated regions and further the gate voltages applied thereto vary in out-of-phase relationship to each other in response to input signal fluctuations, it is possible to keep constant the sum total of two currents flowing through the two constant current MOS FETs (35, 45), thus improving the overall constant current characteristics and therefore the suppression capability against noise inputted in phase to the amplifier.</p> |
