1.引言在资料〔1〕和〔2〕作者提出采用碲镉汞光导探测器的改进型扫描温度计时,发现必须设计一个低噪声前置放大器,以使探测器的能力得以全部发挥出来。在8赫～10千赫频带范围内测得的探测器噪声电平约2.5微伏峰-峰值,其电阻是35欧。系统要求放大器总的稳定性优于0.3％,脉冲响应时间为20微秒,并对20毫秒的脉冲平顶降落小于0.3％。为了达到这种脉冲特性,放大器的 1. INTRODUCTION When authors [1] and [2] proposed an improved scanning thermometer using a mercury cadmium telluride photoconductive detector, they found it necessary to design a low-noise preamplifier so that the capabilities of the detector could be fully exploited. The detector noise level, measured in the 8 to 10 kHz band, is about 2.5 microvolts peak-to-peak and has a resistance of 35 ohms. The system requires that the overall amplifier stability is better than 0.3%, the impulse response time is 20 microseconds, and the 20 millisecond pulse flattop falls less than 0.3%. In order to achieve this pulse characteristic, the amplifier’s