By Sam Oliver

Published: 08:05 AM EST (05:05 AM PST)

Shipments of the iPad, including the second-generation model to be announced by Apple today, are expected to be between 6 million and 6.5 million in the first quarter of 2011, on their way to 40 million for the calendar year.

The numbers from DigiTimes on Wednesday show that Apple expects to significantly ramp up production of the iPad as 2011 wears on. For the initial launch of the iPad 2, Apple is expected to have between 300,000 and 400,000 units available.

Apple reportedly ordered between 1.7 million and 2 million iPads in January and February. Order volumes for March, including the to-be-announced iPad 2, are expected to top 2 million.

Citing industry sources, the report said there were between 1 million and 1.5 million units of iPad inventory in the channel in January. It added that Apple is "already set to phase out the first-generation iPad and let iPad 2 take its place."

In a separate report, DigiTimes also reported that gallium arsenide (GaAs) power amplifer suppliers, including TriQuint Semiconductor and Skyworks Solutions, are expected to benefit from the iPad 2 launch. Visual Photonics Epitaxy Company and Advanced Wireless Semiconductor Company of Taiwan are also said to be GaAs foundry suppliers for the iPad 2.

In February, it was said that more than 60 percent of Apple's initial iPad 2 production would be 3G-capable models. The company is expected to produce three versions of the new iPad: a Wi-Fi-only model, a GSM/UMTS version, and a CDMA/EVDO model.

Apple's official unveiling of its second-generation iPad will take place Wednesday at 10 a.m. Pacific, 1 p.m. Eastern. AppleInsider will have full, extensive coverage.