Buffer Amplifiers Solve VCO Problems

Abstract: Poor isolation of an oscillator circuit's output can cause adverse effect. This article describes key application issues surrounding VCO circuits such as load pulling, supply pushing, phase noise and effects of radiated energy from nearby power amplifiers (PAs). It is shown how using a VCO buffer to isolate the oscillator mitigates these problems. The MAX2472/MAX2473 VCO buffers are introduced along with an application circuit and measurement data.