Mathematical modelling and simulation of a wideband PLL for application in frequency synthesizers

Abstract

In this paper the mathematical modelling of the Voltage Controlled Oscillator, Phase Frequency Detector, Low Pass Filter, Charge pump for designing a PLL circuit is proposed. Based on the modelling schematics are designed and proposed for the application in frequency synthesizer. The main design feature of this modelling is that VCO tunning switches are controlled digitally. The behaviour of PLL under its region of operation is simulated. The effect of temperature variations and insufficient bandgap overlapping on the output frequency of PLL is also presented and discussed. To avoid the current mismatching and residual phase errors the charge pump is modelled as to calibrate by its own circuit. Various simulations are done for the performance analysis of wideband PLL. The proposed design will have its application in frequency synthesizers suitable for multi band transceivers.

Keywords

• Charge pump (CP)
• Loop filter (LPF)
• Bandgap
• VCO
• Phase locked loop (PLL)
• Frequency synthesizer