用于DTV接收机的dB线性可编程增益放大器

dB Linearity Programmable Gain Amplifier Used in DTV

针对DTV零中频接收机的系统要求，通过构造串并联相结合的退化电阻网络设计了一个高线性，宽增益变化范围的dB线性CMOS可编程增益放大器（PGA，Programmable Gain Amplifier）。此可编程增益放大器在SMIC0.18μm CMOS工艺下实现，增益变化范围为0-60dB，最小增益步进0.5dB，带6pF电容负载时-3dB带宽为1.5MHz，且带宽恒定。在增益变化范围内，当输出差分峰峰值为1V时，三阶交调失真在-60dB以下。此PGA在3.3V电压下工作，功耗小于4mW。

With the series parallel resistance network as degeneration resistances, a dB linearity Programmable Gain Amplifier （PGA）,with high linearity and wide gain variation range is implemented under SMIC 0.18μm CMOS process. The gain variation range is 0-60 dB with 0. 5 dB as minimum step size. When loaded by 6 pF capacitor, the -3 dB bandwidth is 1.5 MHz, and it keeps constant in the gain variation range. Its 3rd order inter-modulation distortion is below -60 dB at 1 V peak-to-peak differential output. The power dissipation is less than 4 mW with 3. 3 V supply.