Patent ID: 7202732

Claim:
A transimpedance amplifier comprising: an amplifier circuit for converting a variable input current signal, which has AC and DC components, into an output voltage; and a feedback circuit generating a feedback voltage signal with AC and DC components from the output voltage, the feedback circuit including: a feedback amplifier/low pass filter, defining a low frequency cut off, for removing the AC component of the feedback voltage signal; a bypass transistor, which receives the DC component of the feedback voltage signal and generates a DC feedback current substantially equal to the DC component of the input current signal for removing the DC component of the input current signal, the feedback circuit having a feedback gain; and a linearizing circuit for linearizing the feedback gain as the input current signal varies, including a constant current source for supplementing the DC feedback current through the bypass transistor, thereby reducing a variation in the low frequency cut off caused by the variation in the input current; wherein the input current signal ranges from a low to a high current; and wherein the constant current source generates a constant current equal to or greater than the high current.