Rail-to-rail-input buffer
First Claim
1. A buffer circuit comprising:
- a differential input configured to receive an input signal;
a first differential stage supplied with a first reference current, the first differential stage comprising PMOS-transistors having gate terminals connected to the differential input;
a second differential stage supplied with a second reference current, the second differential stage comprising NMOS-transistors having gate terminals connected to the differential input;
a switching PMOS-transistor operable to, when the input signal is higher than a predetermined first threshold voltage, divert the first reference current from the first differential stage to a first current mirror circuit configured to mirror the first reference current;
a switching NMOS-transistor operable to, when the input signal is lower than a predetermined second threshold voltage, divert the second reference current from the second differential stage to a second current mirror circuit configured to mirror the second reference current;
a third differential stage comprising NMOS-transistors having gate terminals connected to the differential input, wherein the third differential stage is configured to receive the mirrored first reference current when the input signal is higher than the first threshold voltage;
a fourth differential stage comprising PMOS-transistors having gate terminals connected to the differential input, wherein the fourth differential stage is configured to receive the mirrored second reference current when the input signal is lower than the second threshold voltage;
a third current mirror circuit operably connected to receive a first output current of the third differential stage, and operable to mirror the first output current of the third differential stage to a first output current line; and
a fourth current mirror circuit operably connected to receive a second output current of the third differential stage, and operable to mirror the second output current of the third differential stage to a second output current line; and
wherein the third differential state comprises two NMOS-transistors having drain terminals connected to the first current mirror circuit.
1 Assignment
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Accused Products
Abstract
A rail-to-rail-Input Buffer with constant mutual conductance includes a differential input; a first differential stage supplied with a first reference current; a second differential stage supplied with a second reference current; a switching PMOS-transistor which switches through when the input signal is higher than a first threshold voltage to divert the first reference current to a first current mirror circuit; a switching NMOS-transistor which switches through when an input signal is lower than a second threshold voltage to divert the second reference current to a second current mirror circuit; a third differential stage supplied with the mirrored first reference current and replaces the first differential stage when the input signal is higher than the first threshold voltage; and a fourth differential stage supplied with the mirrored second reference current and replaces the second differential stage when the input signal is lower than the second threshold voltage.
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Citations
19 Claims
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1. A buffer circuit comprising:
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a differential input configured to receive an input signal; a first differential stage supplied with a first reference current, the first differential stage comprising PMOS-transistors having gate terminals connected to the differential input; a second differential stage supplied with a second reference current, the second differential stage comprising NMOS-transistors having gate terminals connected to the differential input; a switching PMOS-transistor operable to, when the input signal is higher than a predetermined first threshold voltage, divert the first reference current from the first differential stage to a first current mirror circuit configured to mirror the first reference current; a switching NMOS-transistor operable to, when the input signal is lower than a predetermined second threshold voltage, divert the second reference current from the second differential stage to a second current mirror circuit configured to mirror the second reference current; a third differential stage comprising NMOS-transistors having gate terminals connected to the differential input, wherein the third differential stage is configured to receive the mirrored first reference current when the input signal is higher than the first threshold voltage; a fourth differential stage comprising PMOS-transistors having gate terminals connected to the differential input, wherein the fourth differential stage is configured to receive the mirrored second reference current when the input signal is lower than the second threshold voltage; a third current mirror circuit operably connected to receive a first output current of the third differential stage, and operable to mirror the first output current of the third differential stage to a first output current line; and a fourth current mirror circuit operably connected to receive a second output current of the third differential stage, and operable to mirror the second output current of the third differential stage to a second output current line; and wherein the third differential state comprises two NMOS-transistors having drain terminals connected to the first current mirror circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A buffer circuit having first, second and third operating states, the buffer circuit comprising:
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a differential input configured to receive an input signal; a first differential stage supplied with a first reference current, the first differential stage comprising PMOS-transistors having gate terminals connected to the differential input, the first differential stage configured to generate output currents when the buffer circuit is in the first operating state and when the buffer circuit is in the second operating state; a second differential stage supplied with a second reference current, the second differential stage comprising NMOS-transistors having gate terminals connected to the differential input, the second differential stage configured to generate output currents when the buffer circuit is in the second operating state and when the buffer circuit is in the third operating state; a third differential stage comprising NMOS-transistors having gate terminals connected to the differential input, wherein the third differential stage is configured to generate output currents when the buffer circuit is in the third operating state; a fourth differential stage comprising PMOS-transistors having gate terminals connected to the differential input, wherein the fourth differential stage is configured to generate output currents when the buffer circuit is in the first operating state; a third current mirror circuit operably connected to receive a first output current of the third differential stage, and operable to mirror the first output current of the third differential state to a first output current line; and a fourth current mirror circuit operably connected to receive a second output current of the third differential stage, and operable to mirror the second output current of the third differential stage to a second output current line; and wherein the third differential stage comprises two NMOS-transistors having drain terminals connected to the first current mirror circuit. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification