National Science Council

Terax Communication Technologies Inc.

Wen-Kai Kuo

Sheng-Lung Huang

Ping-Chung Chung

Hsiao-yu Chou

Wen-Fa Chen

Liang-Chih Chang

The present invention discloses a highly efficient constant transconductance power amplifier. an embodiment of the invention comprises a positive error amplifier, a negative error amplifier, four current sources, two differential current controllers, and a constant gm biasing circuit. The amplifiers are used with deliberate offset voltages in order to make two transconductance amplifiers which serve in the positive and negative cycle in order to turn on in the appropriate cycle properly. Positive current sources are current outputs while negative current sources sink the current. The current sources provide current to the current controllers. The differential current controllers control the amount of current from the current source flowing to the load. This is proportional to the differential input signal. The constant transconductance biasing circuit provides the transconductance amplifiers with stable biasing voltage. This eliminates any drift associated with process variation. The invention discloses a more efficient constant transconductance power amplifier which provides improved performance, low power consumption, lower operating voltage, increased dynamic range, and stable processing characteristics.

Highly efficient constant transconductance power amplifier

Two-dimensional electric-filed vector is measured in this invention, wherein two linearly polarized laser beams are focused on two different bottom planes of an electro-optic crystal so that two reflected beams from the bottom planes have two different paths inside the electro-optic crystal and thus have different phase retardation when an electric-field is exerted on the electro-optic crystal by a circuit under test. The electric-filed direction of the circuit can be calculated by using two differential signals which are proportional to the phase retardation of the two reflected beams.

Electro-optic apparatus and method for measuring electric-field vector

Growing community of inventors

Hsinchu, Taiwan

Wen-Kai Kuo