The 30-year-old has been a revelation since rocking up at Franklin's Gardens in the summer of 2018.
Biggar has thrived under boss Chris Boyd and attack coach Sam Vesty, adding new strings to his bow.
He has been one of the players of the current season at Saints, steering the ship superbly at fly-half.
And Biggar continues to revel in taking on other top 10s in the Gallagher Premiership and Champions Cup.
"For me going up against Owen Farrell, (Danny) Cipriani week in, week out is a real bar setter," Biggar said.
"If you're not on the money, you get found out because if you're not on the money, chances are your opposite number is.
"Every week is a challenge for me.
"You look at Sale, who signed Rob du Preez who has made a huge impact up there, and it seems that every team has got a very strong outside half.
"It's what I enjoy. I enjoy a challenge of going up against big names and big reputations.
"I still see myself as I've really got to put myself up against those guys and I've got to compare myself against them and I've got to aspire to be like those guys.
"I don't feel like I'm a 30-year-old guy who has been around the block a little bit, I still see myself as a youngish 20-year-old who is aspiring to get better week in, week out.
"Playing against those types of players in front of packed houses and in a league that is as competitive as anything in the world is brilliant for me."
Biggar agreed to switch to Saints from Ospreys during the 2017/18 season, but it was a turbulent one at Northampton with long-serving boss Jim Mallinder departing.
Boyd agreed to take the job during the following summer and quickly recruited Vesty as attack coach.
And that duo have clearly helped Biggar take his game to new levels during the past couple of campaigns.
"It was really difficult for me because when I signed I signed with Jim Mallinder in charge," Biggar said.
"It was obviously a little bit of a difficult period when he lost his job and Chris came in. He was someone I hadn't really heard a huge amount about.
"But what has benefited me is that between Chris and Sam Vesty in particular, it has been a joy to go into work every day.
"Every day is different, every day is challenging, you feel like you're a better rugby player every time you come off the training pitch.
"What we've got in Chris Boyd, in my opinion, is one of the very best in the business in terms of man-managing, knowing the game inside out and giving the boys confidence to go out and play what's in front of them with the structures we've got.
"For me personally, it's made me a lot more confident in my own ability.
"What I'm good at, I'll always be good at, but perhaps things I wasn't as good at, Chris and Sam Vesty have helped me improve on because of the way we like to play.
"It's benefited me as an all-round player."