We report on a 400 nm broad-band type I frequency doubling in a non-collinear geometry with pulse front tilted and chirped femtosecond pulses (l₀ = 800 nm, FTL pulse duration ~ 45 fs). With moderate power densities (2 to 10 GW/cm²) thus avoiding higher-order nonlinear phenomena, the energy conversion efficiency was up to 65%. Second-harmonic pulses of Fourier transform limited pulse duration shorter than the fundamental wave were generated, exhibiting a good beam quality and no pulse-front tilt. High energy (20 mJ/pulse) was produced in a 40 mm diameter and 6 mm thick LBO crystal. To the best of our knowledge, this is the first demonstration of this optical configuration with sub 100 fs pulses. A good agreement between experimental results and simulations is obtained.