公开(公告)号：EP1696558A1

公开(公告)日：2006-08-30

申请号：EP05425097.2

申请日：2005-02-25

Applicant: STMicroelectronics S.r.l.

Inventor： Scuderi, Angelo ,  Scuderi, Antonino ,  La Paglia, Luca ,  Carrara, Francesco ,  Palmisano, Giuseppe

IPC: H03F1/52 ,  H03G3/30 ,  H03F3/189

CPC classification number: H03F1/52 ,  H03F3/19 ,  H03F2200/447 ,  H03F2200/78 ,  H04B1/0466

Abstract: A novel protection technique and its circuital implementation are presented, which prevent load-mismatch-induced failure in solid-state power amplifiers. In radio- and microwave-frequency power amplifiers, the load voltage standing-wave ratio results in very high voltage peaks at the collector of the final stage (Q 3 ) and may eventually lead to permanent failure of the power transistor due to avalanche breakdown. The proposed solution avoids the risk of breakdown by attenuating the input power to the final stage (Q 3 ) during overvoltage conditions, thus limiting the output collector swing. This is accomplished by means of a feedback control system, which detects the peak voltage at the output collector node and clamps its value to a given threshold by varying the circuit gain. Indeed, the control loop is unlocked in nominal condition and it acts only when an output mismatching condition is detected. Moreover, a newly proposed control circuit allows a supply-independent collector-clamping threshold to be accurately set.

Abstract translation: 提出了一种新颖的保护技术及其电路实现，可以防止固态功率放大器的负载失配引起的故障。 在无线电和微波频率功率放大器中，负载电压驻波比导致在最终级（Q 3）的集电极处的非常高的电压峰值，并且可能由于雪崩击穿而最终导致功率晶体管的永久故障。 所提出的解决方案通过在过电压条件下衰减到最终级（Q 3）的输入功率来避免击穿的风险，从而限制输出收集器摆幅。 这通过反馈控制系统来实现，该系统检测输出收集器节点处的峰值电压，并通过改变电路增益将其值钳位到给定的阈值。 实际上，控制回路在标称状态下被解锁，并且仅在检测到输出失配条件时才起作用。 此外，新提出的控制电路允许精确地设定与电源无关的集电极钳位阈值。