Note 11 - Stock-based Compensation (Tables)

9 Months Ended

Jan. 01, 2017

Notes Tables

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]

	As of		Nine Months Ended
	January 1, 2017		January 1, 2017
					Weighted
	Shares of		Shares of		Average
	Common Stock		Common Stock		Price per Share
Authorized to issue		4,500
Reserved for future issuance		1,298
Issued				19	$	7.54

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

						Weighted
						Average				In-the-money
				Weighted		Remaining		Aggregate		Options
	Outstanding			Average		Contractual		Intrinsic		Vested and
	Options /			Exercise		Term		Value		Exercisable
	Quantity			Price per Share		(in years)		(in thousands)		(in thousands)
Balance at March 27, 2016		7,722,383		$	7.96		4.40	$	87		48
Granted		1,466,800			7.30
Exercised		(2,045,504	)		6.97
Cancelled		(614,454	)		9.84
Forfeited		(1,055,074	)		7.53
Balance at January 1, 2017		5,474,151			8.02		4.66		16,195		4,787
Vested and expected to vest, January 1, 2017		4,909,103			8.12		4.50		14,140
Vested and exercisable, January 1, 2017		2,491,344		$	8.85		3.19	$	5,620

Schedule of Cash Proceeds Received from Share-based Payment Awards [Table Text Block]

	Three Months Ended				Nine Months Ended
	January 1,		December 27,		January 1,		December 27,
	2017		2015		2017		2015
Intrinsic value of options exercised	$	1,367	$	39	$	4,085	$	637

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

						Weighted
						Average
				Weighted		Remaining		Aggregate
				Average		Contractual		Intrinsic
				Grant-Date		Term		Value
	Shares			Fair Value		(in years)		(in thousands)
Unvested at March 27, 2016		590,833		$	9.39		1.45	$	3,108
Granted		622,039			8.63
Issued and released		(209,236	)		8.94
Forfeited		(215,029	)		9.68
Unvested at January 1, 2017		788,607		$	8.83		1.81	$	8,501
Vested and expected to vest, January 1, 2017		608,111					1.62		6,555

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Three Months Ended				Nine Months Ended
	January 1,		December 27,		January 1,		December 27,
	2017		2015		2017		2015
Cost of sales	$	474	$	98	$	889	$	257
Research and development		926		117		1,696		509
Selling, general and administrative		2,234		596		4,546		3,044
Total stock-based compensation expense	$	3,634	$	811	$	7,131	$	3,810

Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block]

	January 1, 2017
			Weighted
			Average
			Remaining
	Amount		Recognition
	(in thousands)		Period (in years)
Options	$	4,887		2.59
RSUs		4,557		2.58
PRSUs		630		1.69
Total unrecognized stock-based compensation expense	$	10,074

Performance-based Restricted Stock Units [Member]

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

Expected term of grants (years)	3
Risk-free interest rate	0.76	%
Expected volatility	50	%