Spurious noise reduction by modulating switching frequency in DC-to-DC converter for RF power amplifier

Author

Kim, Eung Jung ; Cho, Chang-Hyuk ; Kim, Woonyun ; Lee, Chang-Ho ; Laskar, Joy

Author_Institution

Georgia Electron. Design Center, Georgia Inst. of Technol., Atlanta, GA, USA

fYear

2010

fDate

23-25 May 2010

Firstpage

43

Lastpage

46

Abstract

The presence of a spectrum spreading effect in a DC-to-DC converter operating in Pulse-Width Modulation (PWM) with a modulated switching frequency is analyzed. A step-down DC-to-DC converter prototype with a digital PWM ramp signal modulator is implemented in a standard CMOS 0.18-μm process. The step-down DC-to-DC converter has an 6-bit up/down binary counter to vary its switching frequency between 2.2 MHz and 4.4 MHz in 64 steps as means of decreasing spurious noise peaks at the output of the switch converter. The measurement results show that the spurious switch noise peak is reduced by 12 dB when a monotonic frequency stepping with the up/down counter is used, and it is shown that the additional switching frequency modulation functionality does not degrade the overall efficiency and the closed loop operation significantly.

Keywords

CMOS analogue integrated circuits; PWM power convertors; frequency modulation; modulators; power amplifiers; radiofrequency amplifiers; switched mode power supplies; switching convertors; RF power amplifier; digital PWM ramp signal modulator; frequency 2.2 MHz; frequency 4.4 MHz; monotonic frequency stepping; pulse-width modulation convertors; size 0.18 mum; spectrum spreading effect; spurious noise reduction; spurious switch noise; standard CMOS process; step-down DC-to-DC converter; switch converter; switch power; switching frequency modulation functionality; up-down binary counter; DC-DC power converters; Frequency modulation; Noise reduction; Power amplifiers; Pulse width modulation; Pulse width modulation converters; Radio frequency; Radiofrequency amplifiers; Switching converters; Switching frequency; DC-to-DC converter; modulated PWM; spread spectrum; switch power supply;

fLanguage

English

Publisher

ieee

Conference_Titel

Radio Frequency Integrated Circuits Symposium (RFIC), 2010 IEEE

Conference_Location

Anaheim, CA

ISSN

1529-2517

Print_ISBN

978-1-4244-6240-7

Type

conf

DOI

10.1109/RFIC.2010.5477360

Filename

5477360