By Harley Berman
The What and Why of Limiters
Limiters are crucial building blocks in Tx/Rx systems and are used to protect sensitive circuity from high power signals. Take for example a simple radar system, which consists of a high-power pulse transmitter sharing an antenna with the Rx signal chain shown below. The pulse exiting the power amplifier is well above the damage threshold of the LNA and, depending on the isolation of your duplexer, this pulse has the ability to cause catastrophic damage to your LNA. To solve this problem, system designers commonly place a limiter between the antenna and LNA, which protects the sensitive LNA and Rx signal chain.