Patent ID: 8957709
Filing Date: 2015-02-17
Classification: H01S

Abstract:
1. A driver circuit, comprising: a front amplifier supplied with a primary power supply; a rear amplifier put in a downstream of the front amplifier, the rear amplifier being supplied with a secondary power supply higher than the primary power supply, the rear amplifier including a current source, a switching transistor, a cascade transistor, and a load resistor connected in series in this order between a ground and the secondary power supply, the cascade transistor being based by a bias source; a booster configured to generate the secondary power supply from the primary power supply, wherein the bias source lowers a base bias of the cascade transistor when the primary power supply becomes active but the secondary power supply is left inactive, and raises to a voltage substantially equal to the primary power supply when both of the primary power supply and the secondary power supply become active but the rear amplifier is left inactive.