INJECTION LOCKING A SLAVE OSCILLATOR TO A MASTER OSCILLATOR WITH NO FREQUENCY OVERSHOOT

摘要

An injection locked oscillator circuit includes a master oscillator a slave oscillator and an injection lock control circuit. The slave oscillator is decoupled from the master oscillator (for example due to an unlock condition). When the slave is free running its oscillating frequency is adjusted (for example as a function of a supply voltage). After an amount of time the slave is to be relocked to the master (for example due the unlock condition no longer being present). The slave oscillating frequency is made to be slightly lower than the master oscillating frequency. The slave is then only recoupled to the master upon detection of an opposite phase condition between the master oscillator output signal and the slave oscillator output signal. By only recoupling the slave to the master during opposite phase conditions frequency overshoots in the slave oscillating frequency are avoided that may otherwise occur were the recoupling done during in phase conditions.