Transconductance Operational Amplifier for Wide Input Range Applications

Abstract

The invention discloses a transconductance operational amplifier suitable for wide input range applications, which includes an input stage circuit, a current mirror circuit and a voltage latch pair. The input stage circuit includes an input transistor pair and a bias transistor pair. The input transistor pair is electrically connected to the bias transistor pair through two end points inside the input stage circuit. The first bias terminal and the second bias terminal of the current mirror circuit are electrically connected to two end points respectively. The voltage latch pair has a first latch circuit and a second latch circuit. The first latch circuit and the second latch circuit are electrically connected to a ground terminal or a system voltage terminal, and are electrically connected to the bias transistor pair, and Electrically connect the two endpoints respectively. The first latch circuit and the second latch circuit are used to latch the voltages at the two end points at a specific voltage, or to make the voltages at the two end points the same as each other.

Description

technical field [0001] The present invention relates to a transconductance operational amplifier (Operational Transconductance Amplifier, OTA), and more particularly to a transconductance operational amplifier suitable for wide input range applications, wherein wide input range applications include, for example, LED driver applications. Background technique [0002] For the switchable LED device, it needs the LED driver to generate pulse width modulation signal to drive. The pulse width modulator for generating the pulse width modulation signal will have a transconductance operational amplifier, and the transconductance operational amplifier amplifies the error signal between the reference voltage and the feedback voltage generated according to the feedback current of the LED, Thus, the PWM adjusts the period of duty cycle of the PWM signal. [0003] Please refer to figure 1 , figure 1 is a schematic circuit diagram of a conventional transconductance operational amplifier...

AI Technical Summary

Problems solved by technology

However, in the application of the LED driver, the second input voltage VREF may be 0.2 volts, and the first input voltage may be a triangular wave voltage signal with an average voltage of 0.2 volts and a maximum swing voltage of 1 volt. Therefore, the P-type transistor MP1 , MP2 drain / source voltage V DS1 with V DS2 (corresponding to the voltages of terminals aa and bb) are not consistent

The drain terminal / source terminal voltage V of P-type transistors MP1 and MP2 DS1 with V DS2 Determine the transconductance coefficient g of the P-type transistors MP1 and MP2 respectively m1 、g m2 , and cause current mirror circuits MN1, MN5 and MN2, MN6 to cause copy current offset due to channel length modulation, so if the drain terminal / source terminal voltage V of the P-type transistor MP1, MP2 DS1 with V DS2 Inconsistency will cause the output signal COMP to be offset (offset)

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