一种摆率可控的 PD 发射机模拟前端电路的设计

文章针对通用串行总线(universal serial bus, USB)电源传输协议(power delivery, PD)通信过程中的电磁干扰(electromagnetic interference, EMI)以及传统电路中电容不同带来的工艺偏差的影响, 从电路层面对PD发射机模拟前端进行优化设计, 提出一种摆率可控的PD发射机模拟前端电路。采用同一电流双路对称镜像进行单电容充放电结构, 抑制了电容不同带来的工艺偏差的影响, 并通过调节电流进行摆率控制, 可有效抑制电磁干扰, 输出级采用高增益两级运放组成的驱动器来提供强驱动能力。采用HHGRACE 0.35μm BCD工艺进行电路和版图设计, 利用Spectre和Hspice软件进行仿真验证。仿真结果表明, 设计指标满足USB PD协议标准的要求。

Aiming at electromagnetic interference (EMI) in universal serial bus power delivery (USB PD) communication and the influence of process deviation caused by different capacitors in traditional circuit, the analog front end circuit of PD transmitter is optimized at the circuit level, and a kind of analog front end circuit of PD transmitter with controllable slew rate is proposed. The circuit adopts a structure with the same current double symmetric mirror to charge or discharge a single capacitor, which can restrain the impact of process deviation caused by the different capacitors, and controls the slew rate by adjusting the current, which can suppress EMI effectively. In order to provide strong driving capacity, a driver which consists of two operational amplifiers with high gain is adopted for the output stage. HHGRACE 0.35 $ \mu $m BCD process is used for circuit and layout design, and Spectre and Hspice are used for simulation verification. The simulation results show that the design indicator meets the requirements of USB PD protocol standard.