Design of the phase-lock loop for wide band CDMA transmitter

Error vector magnitude (EVM) is a key parameter for modern wireless communication, and the local oscillator (LO) is a critical block for transmitter performance. Implementing a phase-lock loop (PLL) design based on the EVM specification is challenging for radio designers. The paper provides a series of solutions to this issue. Firstly, the paper deduces and analyzes the relationship between the EVM and the phase noise density of the PLL. Several key equations are discussed and an EVM simulation program is written which can be used together with a PLL simulation program for accurate PLL parameter determination based on the EVM specification. Finally, as a practical application, the paper introduces a PLL circuit design of a wide band CDMA transmitter based on frequency direct conversion technology.