If you want to fight with Broadcom, you'd better be willing to put in some overtime.

At least that's what the chipmaker implied this week in an SEC filing addressed to Qualcomm —the latest document in an M&A struggle between the two rivals. In the filing, Broadcom CEO Hock Tan writes to Qualcomm executive chairman Paul Jacobs that he was "astonished" Qualcomm did not accept a weekend meeting to discuss a potential merger.

"Broadcom has long sought a meeting to discuss Broadcom's acquisition of Qualcomm. Following Qualcomm's announcement today that it is willing to meet with us, we offered to meet with Qualcomm on Friday, Saturday or Sunday. I was astonished to hear that Qualcomm is not willing to meet until Tuesday — only after Qualcomm's and Broadcom's respective meetings with Glass Lewis and ISS," Tan wrote in the official letter.