Senate hearings on the nomination of Sherman E. Unger to the new U.S. Court of Appeals for the Federal Circuit ended yesterday, with the American Bar Association pressing its charges that he is unqualified 'nd Unger suggesting that he has changed after a bout with cancer.

Unger, 56, whose nomination the ABA's Committee on the Judiciary unanimously recommended be rejected because of a "lack of personal integrity and judicial temperament," was criticized further in five appearances before the Senate Judiciary Committee.

The charges include falsifying affidavits, improper contact with a bankruptcy judge, receiving improper payments in a bankruptcy case, failing to report $40,000 in income on his 1968 federal income tax return and threatening to commit suicide and blame it on a former employer after he was fired from a job.

Reacting bitterly to the 14-month "paper chase" that he said the ABA has forced him through, Unger said, "During that period, I went through a bout with cancer. I sit here by the grace of God . . . . The man you are asked to confirm today may not be the same man" who has been criticized in earlier testimony. "Events change people," he said.

On the tax question, Unger said he filed an amended return the following year when he discovered the mistake. "There is no way for me to explain how I forgot that payment . . . . I don't think it is of great importance whether I revealed it to the IRS first or whether they had started an audit."

Former transportation secretary William T. Coleman Jr., representing the ABA, said yesterday that in the ABA judicial screening process, "there were at least 11 instances in which Mr. Unger told the ABA committee things which later turned out to be untrue."

Unger, now general counsel at the Commerce Department, denied any deliberate wrongdoing and criticized the ABA process of screening federal judges for the White House.

Unger charged that the ABA has been "less than fair . . . . What I went through with the ABA wasn't exactly what I'd call a friendly gathering . . . . I felt I was being cross-examined and treated like a second-rate defendant."

"The ABA has wedged itself between the nominating process of the president of the United States and the confirmation process of the Senate of the United States," Unger said. "I would be a good judge. I want to be a judge."

No committee vote on the nomination has been scheduled.