Andy Miller, Apple’s Vice President of Mobile Advertising, is leaving the company to join Highland Capital, reports All Things D. The venture firm funded Miller’s advertising company Quattro Wireless, which was snapped up by Apple in 2007 after it lost out on a purchase of competing firm AdMob to Google.

Quattro operated as Apple’s primary way of delivering mobile ads until it fired up the iAd platform last year. The departure is notable as, after a launch with large partners and an initial boom in ad revenue for developers, Apple has recently been struggling in the mobile advertising arena, slashing prices on advertising buys to boost adoption.

Miller is leaving for Highland Capital, a venture firm that funded Quattro back when Miller was its head and will work on digital investments from the firm’s Silicon Valley office.

The iAd platform was created in order to present iOS device users with richer and more interactive web experiences than traditional mobile advertising had been providing up to that point.