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设计了一款低噪声、高单位增益带宽的运放电路。该款电路基于0.25μm SiGe双极工艺,采用三级级联的形式,输入级选取多个双极型晶体管(BJT)并联,用作差分对管,以抑制噪声;中间级不但用pnp型BJT镜像电流源作为有源负载,而且并联多个横向pnp型BJT用以提升单位增益带宽;输出级则设计成低电容输入和低电容输出方式,借此拓展带宽。对所设计的运放电路进行了PSPICE仿真及硬件电路实验。结果表明,当电源电压为2.5 V时,运放电路的实测交流开环电压增益为80 dB,开环相位裕度为61.5°,单位增益带宽为203 MHz,在10 kHz处的输入电压噪声密度仅为1.2 nV/Hz~(1/Hz),因而可用于低噪声、高单位增益带宽的片上相位噪声测量电路和微波功率传感器等系统的设计中。
A low noise, high unity gain bandwidth op amp circuit is designed. The circuit is based on a 0.25μm SiGe bipolar process and uses three stages of cascades. The input stage selects multiple bipolar transistors (BJTs) in parallel and serves as a differential pair to suppress noise. The intermediate stage uses not only the pnp BJT The mirrored current source acts as an active load and multiple lateral pnp-type BJTs are connected in parallel to boost the unity-gain bandwidth. The output stage is designed with low-capacitance inputs and low-capacitance outputs to broaden the bandwidth. The design of the op amp circuit PSPICE simulation and hardware circuit experiments. The results show that the measured AC open-loop voltage gain of op amp circuit is 80 dB, the open-loop phase margin is 61.5 ° and the unity gain bandwidth is 203 MHz when the supply voltage is 2.5 V. The input voltage noise density Only 1.2 nV / Hz ~ (1 / Hz), which can be used for low noise, high unity gain bandwidth on-chip phase noise measurement circuit and microwave power sensors and other systems design.