High bandwidth transimpedance amplifier

An imaging system comprising:

• an array of photo diodes configured to detect electron pulses;
• and
• a transimpedance amplifier (TIA) circuit coupled to each of the photo diodes, the TIA circuit comprising:
• a pre-amplifier stage configured to amplify an input signal provided by the photo diode, the pre-amplifier stage comprising a first P-channel metal oxide semiconductor field effect transistor (MOSFET) (P1), a second P-channel MOSFET (P2), a first N-channel MOSFET (N1), and a second N-channel MOSFET (N2), coupled in series, wherein a gate of P1 and a gate of N2 are driven by the input signal, and an output of the pre-amplifier stage is provided at a coupling between a drain of P2 and a drain of N1;
• and
• an active resistor network configured to provide a variable resistance based on a provided current bias, the active resistor network coupled between the gates of P1 and N2, and the drains of P2 and N1, the variable resistance is used to control a gain of the pre-amplifier stage;
• wherein the TIA circuit further comprises a programmable current bias circuit configured to generate the current bias for the active resistor network based on a provided digital gain control signal.

A method for fabricating a transimpedance amplifier (TIA), the method comprising:

• configuring a pre-amplifier stage to amplify an input signal, the pre-amplifier stage comprising a first P-channel metal oxide semiconductor field effect transistor (MOSFET) (P1), a second P-channel MOSFET (P2), a first N-channel MOSFET (N1), and a second N-channel MOSFET (N2), coupled in series;
• coupling a gate of P1 and a gate of N2 to a port configured to receive the input signal;
• providing an output port of the pre-amplifier stage at a coupling between a drain of P2 and a drain of N1;
• configuring an active resistor network to provide a variable resistance based on a provided current bias;
• coupling the active resistor network between the gates of P1 and N2, and the drains of P2 and N1, the variable resistance is used to control a gain of the pre-amplifier stage;
• and
• configuring a programmable current bias circuit to generate the current bias for the active resistor network based on a provided digital gain control signal.