The $70 a share bid is comprised of $60 in cash and $10 per share in stock, which would value Qualcomm at $103 billion. It also includes Broadcom's willingness to have Qualcomm complete its pending acquisition of NXP Semiconductors for more than $38 billion in cash, sources told CNBC.
But the bid stands whether that acquisition is completed or not, Broadcom said.
Qualcomm shares rose 4 percent to $64.43 a share in premarket trading. The deal's total value is $130 billion when including $25 billion in net debt.
The stock, traded on the Nasdaq, surged by more than 12 percent on Friday amid speculation that Broadcom was preparing a bid. It finished the session at $61.81. Broadcom's offer is at a premium of 27.6 percent to Qualcomm's closing price of $54.84 on Thursday, a day before media reports of a potential deal pushed up the company's shares.
Broadcom has been working on its proposal for months — a bold bid to become a dominant supplier of communications chips to the wireless industry — and is believed to have approached Qualcomm privately about its offer, but was quickly rebuffed, sources told CNBC. The company had originally considered an attempt to buy Qualcomm prior to that company's deal to buy NXP more than one year ago, but upon getting no traction at that time, retreated.
This time, Broadcom is determined to bring its offer to the attention of Qualcomm shareholders. People familiar with the company's thinking indicate Broadcom will not shy away from initiating a proxy fight to gain seats on Qualcomm's board of directors in support of its offer.
Qualcomm's annual meeting is currently scheduled for March with the deadline for nominating directors sometime in December.
The chipmaker confirmed Monday morning that it received the Broadcom offer and said in a statement, "Qualcomm Board of Directors, in consultation with its financial and legal advisors, will assess the proposal in order to pursue the course of action that is in the best interests of Qualcomm shareholders."
Qualcomm, however, is expected to strongly resist Broadcom's proposal. People close to the company expect it to indicate the offer price is far below what it would expect in a takeover. In addition, Qualcomm is expected to raise concerns that any combination with Broadcom would raise significant antitrust concerns.
While Broadcom is expected to indicate its willingness to let Qualcomm complete its deal to acquire NXP, it is also expected to encourage the company not to raise its current $110 per share cash deal to acquire the company. Qualcomm is under pressure from NXP shareholders to raise its bid for that chip company, or face the likely prospect it will not be able to meet the minimum threshold needed to take control of the company under Dutch law.
A tie-up would combine two of the largest makers of wireless communications chips for mobile phones and raise the stakes for Intel, which has been diversifying into smartphone technology from its stronghold in computers.
— Reuters contributed to this report.