SUPPRESSING PHASE LOCKED LOOP GAIN FLUCTUATIONS IN WIDEBAND LINEARLY FREQUENCY MODULATED WAVEFORM SYNTHESIZERS

Abstract

Wideband linearly frequency modulated (LFM) signals are required for many communication navigation applications; however, a limiting factor is the presence of frequency nonlinearity which degrades the system performance significantly. The fluctuations of phase locked loop (PLL) loop gain and voltage controlled oscillator (VCO) gain will results in inconsistent frequency nonlinearity performance in the whole frequency band. In this letter, we propose an effective solution by real-timely tuning the phase/frequency detecting current, along with the iterative compensation algorithm. In this way, the frequency nonlinearity is compensated and a wideband LFM waveform synthesizer can be designed. This approach is validated by experimental results.