Charles B. Coyer, a former Washington developer who pleaded guilty to a charge of using money from a would-be investor for personal expenses, was sentenced in federal court here yesterday to a term of one to three years in prison.

In exchange for Coyer's guilty plea to one count of larceny after trust, the government agreed to drop remaining charges in a 14-count indictment that alleged he defrauded or attempted to defraud investors in two real estate projects of $155,000.

Assistant U.S. Attorney Judith Hetherton alleged in court papers that Coyer, who now lives in Hilton Head, S.C., had engaged in a "pattern of fraudulent conduct over at least the past 11 years," much of which involved real estate investment deals. Coyer was one of the developers of the Canal Square complex in Georgetown.

Hetherton told Judge Louis F. Oberdorfer at the sentencing hearing yesterday that Coyer also had failed to file federal income tax returns from 1976 to 1980.

Coyer told Oberdorfer yesterday that "the contrition and remorse because of what I have done. . . is hardly describable."

Oberdorfer ordered him to surrender to law enforcement authorities within 30 days to begin serving the prison term.