High-speed output transconductance amplifier capable of operating at different voltage levels

A high-speed output transconductance amplifier (OTA) capable of operating at different voltage levels, comprising:

• an NMOS current mirror circuit consisting of a first NMOS with a drain and a gate, and a diode-configured NMOS with a drain and a gate connected to the gate of the first NMOS and the drain of the diode-configured NMOS;
• two PMOS current mirror circuits consisting of a first PMOS with a gate and a drain connected to the drain of the first NMOS to form a connection point as an output terminal, a second PMOS with a gate and a drain connected to the drain of the diode-configured NMOS, a first diode-configured PMOS with a drain and a gate connected the drain of the first diode-configured PMOS and the gate of the first PMOS, and a second diode-configured PMOS with a drain and a gate connected to the drain of the second diode-configured PMOS and the gate of the second PMOS;
• a cross-coupled circuit consisting of a first cross-coupled unit having a first programmable switch and a third PMOS connected in parallel to the first PMOS, with a gate connected to the first programmable switch, and a second cross-coupled unit having a second programmable switch and a fourth PMOS connected in parallel to the second diode-configured PMOS, with a gate connected to the second programmable switch;
• and
• a differential operational amplifier consisting of a second NMOS with a drain connected to the first switch and the drain of the second diode-configured PMOS, a gate connected to a first voltage, and a source, a third NMOS with a drain connected to the second switch and the drain of the first diode-configured PMOS, a gate connected to a second voltage, and a source, and a fourth NMOS with a drain connected to the sources of the second and third NMOSs and a gate connected to a third voltage, wherein the first NMOS, the fourth NMOS, and the first diode-configured NMOS respectively are grounded.