The Cobblers had secured a famous win over Liverpool in the third round, but rarely looked like recreating that success at Portman Road
Sven-Goran Eriksson's time as England manager coincided with the Three Lions playing away from Wembley, meaning he has never led a team out at the home of English football. He will have to wait a bit longer after his Leicester City side were beaten 4-1 at home by West Bromwich Albion.
Swansea City also bowed out of the competition, with former manager Roberto Martinez's Wigan Athletic side 2-0 winners at the DW Stadium.
Brentford were beaten 4-3 on penalties at Birimingham CIty after a 1-1 draw, with Maik Taylor saving from Craig Woodman in the decisive spot-kick.
Burnley are the last remaining Championship side with hope of joining Ipswich in the last eight, but they face the daunting trip to Aston Villa on Wednesday night.
The evening's other ties see Newcastle host Arsenal and West Ham take on Stoke City.