Net Revenue by Product Line (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 28, 2012	Dec. 30, 2011
Segment Reporting Information [Line Items]
Total net revenue	$ 44,394	$ 33,932
New Product Lines
Segment Reporting Information [Line Items]
Total net revenue	44,394	33,932
New Product Lines | High-Performance Analog
Segment Reporting Information [Line Items]
Total net revenue	19,190	14,344
New Product Lines | Developed Technology
Segment Reporting Information [Line Items]
Total net revenue	6,000	90
New Product Lines | Communication Processors
Segment Reporting Information [Line Items]
Total net revenue	14,630	19,226
New Product Lines | Wireless Infrastructure
Segment Reporting Information [Line Items]
Total net revenue	4,574	272
Historical Product Lines
Segment Reporting Information [Line Items]
Total net revenue	44,394	33,932
Historical Product Lines | High-Performance Analog
Segment Reporting Information [Line Items]
Total net revenue	19,190	14,344
Historical Product Lines | Communications Convergence Processing
Segment Reporting Information [Line Items]
Total net revenue	14,051	14,989
Historical Product Lines | Wide Area Network Communications
Segment Reporting Information [Line Items]
Total net revenue	5,153	4,509
Historical Product Lines | Developed Technology
Segment Reporting Information [Line Items]
Total net revenue	$ 6,000	$ 90