The pension is in addition to $5.5 million the university said in March it would pay to Paterno's estate to settle his unexpired contract as head coach.
Paterno died less than three months after being ousted by trustees in the aftermath of child sexual-abuse charges against retired defensive coordinator Jerry Sandusky.
University spokesman Dave La Torre declined to comment on Paterno's pension, saying, "That is a state retirement system thing. That really has nothing to do with us."
The State Employees' Retirement System (SERS) said that it could not comment Tuesday on Paterno's pension.
"The Paterno family has said they expect payment by the end of the month. Given that SERS doesn't provide information on a member's benefit until a payment is released, we are not yet in a position to discuss any specifics of this particular member's payment," agency spokeswoman Pamela J. Hile said.
The pension was determined on the basis of a formula, taking into account salary and years of service, that is used for all state employees.
"What makes Joe Paterno's situation unique is . . . he worked the equivalent of two careers," McGinn said, referring to his length of service at Penn State.
Penn State for years refused to talk about Paterno's compensation. But in 2010, in response to a right-to-know request under Pennsylvania law, it released salaries of top executives.
The report showed that Paterno's 2009 compensation of $1,022,794 was about $102,000 greater than what was paid to the second-ranking earner, Harold Paz, dean of the medical school.
McGinn said Paterno was "under-compensated" compared with some other big-time college football coaches and wanted it that way.
Indeed, Urban Meyer, the coach at Ohio State University, earns $4 million a year. Tommy Tuberville, at Texas Tech, makes $2 million.
Paterno, in addition to his university compensation, made undisclosed sums of money as a shoe endorser for Nike and as a paid banquet speaker.
The Paternos, who lived modestly in the State College home they had owned since 1969, gave about $7.5 million to the university and other charitable causes. That included funds for the main library - renamed the Paterno-Pattee Library - and the independent Catholic center on campus, renamed the Suzanne Pohland Paterno Catholic Student Faith Center.
McGinn said the additional donation of $1.5 million would be made up of $500,000 for the Catholic center, which is independent of the university, and $1 million for the Paterno Foundation, which benefits the Special Olympics and other charities.
Contact Tom Infield at 610-313-8205 or firstname.lastname@example.org, or follow on Twitter @tinfield.