US 5,059,920 A · CMOS amplifier with offset adaptation

Abstract

Electrons may be placed onto and removed from a floating node associated with at least one MOS transistor, usually the gate of the transistor, in an analog manner, by application of first and second electrical control signals. A first electrical control signal controls the injection of electrons onto the floating node from an electron injection structure and the second electrical control signal controls the removal of electrons from the floating node by an electron removal structure. An analog MOS integrated circuit comprises an amplifier circuit having a gain much larger than 1. The inverting input into one stage of this amplifier circuit is a floating node forming the gate of at least one MOS transistor. A first capacitor couples an input of the circuit to this floating node. Electrical semiconductor structures are provided for both linearly adding and removing charge from the floating gate, thus allowing the offset voltage of the amplifier to be adapted. An integrated circuit amplifier having a random input offset voltage is adaptable such that the input offset voltage may be cancelled out. An inverting input node is a floating input node and is coupled to a source of input signal by a first capacitor. A second capacitor is connected between the output of the amplifier and the floating node. An electrical learning means allows the floating node to be charged or discharged to a voltage which effectively cancels the input offset voltage.

Claims18

Dependent claims

An analog MOS auto-compensating amplifier fabricated on a semiconductor substrate as a part of an integrated circuit, including:

an input node,
an output node,
an amplifier having an input connected to a floating node and an output connected to said output node,
an MOS capacitor having a first plate connected to said input node and a second plate connected to said floating node,
a source of an electrical control signal,
electron injecting means coupled to said floating node and responsive to said electrical control signal for injecting electrons on to said floating node while the voltage on said floating node is within the normal operating range of said amplifier, said electron injecting means operating to vary the rate of injection of electrons on to said floating node in response to the magnitude of said electrical control signal.

3 more elements

An analog MOS auto-compensating amplifier fabricated as a part of an integrated circuit on a semiconductor substrate, including:

an input node,
an output node,
an amplifier having an input connected to a floating node and an output connected to said output node,
an MOS capacitor having a first plate connected to said input node and a second plate connected to said floating node,
sources of first and second electrical control signals,
electron injecting means coupled to said floating node and responsive to said first electrical control signal for injecting electrons on to said floating node while the voltage on said floating node is within the normal operating range of said amplifier, said electron injecting means operating to vary the rate of injection of electrons on to said floating node in response to the magnitude of said first electrical control signal,
electron removal means coupled to said floating node and responsive to said second electrical control signal for removing electrons from said floating node while the voltage on said floating node is within the normal operating range of said amplifier, said electron removal means operating to vary the rate of removal of electrons from said floating node in response to the magnitude of said second electrical control signal.

4 more elements

An analog MOS auto-compensating amplifier fabricated as a part of an integrated circuit on a semiconductor substrate, including:

an input node,
an output node,
an amplifier having an input connected to a floating node and an output connected to said output node,
a MOS capacitor connected between said input node and said floating node,
electrical control signal generating means coupled to said floating node, for selectively generating an electrical control signal having a magnitude which is a monotonic function of the voltage on said floating node,
electron injecting means coupled to said floating node and responsive to said electrical control signal for injecting electrons on to said floating node while the voltage on said floating node is within the normal operating range of said amplifier, said electron injecting means, when enabled, operating to increase the rate of injection of electrons on to said floating node in response to an increase in voltage on said floating node.

3 more elements

Dependencies are inferred from the claim text.

CMOS amplifier with offset adaptation

Life of this patent

CMOS amplifier with offset adaptation

Life of this patent

Abstract

Claims18