CMOS/SOS frequency synthesizer LSI circuit for spread spectrum communications

• Published in: IEEE journal of solid-state circuits Vol. 19; no. 4; pp. 497 - 506
• Main Authors: Sunderland, D.A., Strauch, R.A., Wharfield, S.S., Peterson, H.T., Cole, C.R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-08-1984; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Circuits; Clocks; CMOS technology; DC generators; Exact sciences and technology; Frequency synthesizers; Ionizing radiation; Large scale integration; Satellite communication; Spread spectrum communication; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Wideband; Microelectronic fabrication; Complementary MOS technology; Spread spectrum; Synthesizer; Frequency synthesizer; Digital transmission; Silicon on sapphire technology
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.1984.1052173

Using a 3.5-/spl mu/m gate length complementary metal-oxide-semiconductor/silicon-on-sapphire technology, a single-chip, radiation-hardened, direct digital frequency synthesizer has been developed. The circuit is a critical component of a fast-tuning wideband frequency synthesizer for spread spectrum satellite communications. During each clock period the chip generates a new digitized sample of a sine wave, whose frequency is variable in 2/SUP 20/ steps from DC to one-half the clock frequency. Operation at up to 7.5 MHz is possible in a worst-case environment, including ionizing radiation levels up to 3/spl times/10/SUP 5/ rads(Si). A computationally efficient algorithm was chosen, resulting in 12-bit output precision with only 1084 logic gates and 3840 bits of on-chip read-only memory. The accuracy of the algorithm is sufficient to maintain in-band spurious frequency components below -65 dBc. At 300 mW, the chip replaces an MSI implementation which uses 25 integrated circuits and consumes 3.5 W.