Design of high-speed low-noise pre-amplifier for CCD camera

Pre-amplifier circuit is critical for the noise performance of the high speed CCD camera. Its main functions are amplification and impedance transform. The high speed and low noise pre-amplifier of CCD camera is discussed and designed in this paper. The high speed and low noise operational amplifier OPA842 is adopted as the main part. The gain-set resistors for the amplifier are designed optimally. The different precision gain-set resistors are swept using Monte Carlo method. CCD video signal which has high DC offset voltage is AC coupled to the amplifier. The output signal of the amplifier is source terminated using 50 ohms matching resistor so as to transmit the video signal through coaxial cable. When the circuit works in high speed, the PCB will have important effect to circuit performance and can even cause the amplifier unstable due to the parasitic problem of PCB. So the parasitic model of the PCB is established and the PCB layout design issues are also presented. The design result shows that the pre-amplifier can be used in the camera whose pixel rate could be up to 40 MHz and its input referred noise density is about 3 nV/Hz1/2.