Switchable operational amplifier circuit
View Patent ↗An amplifier circuit in particular configured as an operational transconductance amplifier has signal paths switched in parallel to the individual transversal branches or signal paths, which can be alternatively activated and deactivated with the aid of suitable switching means ( 1, 2 ), so that without essentially changing the dynamic characteristics of the amplifier circuit switching over is possible by activating these parallel-switched additional signal paths or the transistors (M 3.2 –M 12.2 ) contained in these from normal operation (A) into an operation (B) with, for example, a higher clock frequency in comparison to normal operation or for operating with higher loads in comparison to normal operation.
1. An amplifier comprising:
an input stage comprising
an input operably configured to receive an input signal,
a first input path operably connected to the input and comprising at least one transistor element,
a second input path comprising at least one transistor element, the second input path parallel to the first input path and operably connected to the input,
a first biasing voltage connection operably connected to the at least one transistor element of the first input path and switchably connected to the at least one transistor element of the second input path, and
an input stage output operably connected to the first input path and to the second input path and configured to output the received input signal; and
an output stage comprising
a first output path operably connected to the input stage output and comprising at least one amplifier,
a second output path comprising at least one amplifier, the second output path symmetrical to the first output path and operably connected to the input stage output,
a second biasing voltage connection operably connected to the at least one amplifier of the first output path and switchably connected to the at least one amplifier of the second output path, and
an output operably connected to the first output path and to the second output path and configured to output an amplified received input signal.
2. The amplifier of claim 1 , wherein:
the at least one amplifier of the first output path comprises a control port, a first signal connection operably connected to the input stage output, and a second signal connection operably connected to the output stage output;
the at least one amplifier of the second output path comprises a control port, a first signal connection operably connected to the input stage output, and a second signal connection operably connected to the output stage output; and
the output stage further comprises a first switch arrangement connected to the control port of the at least one amplifier of the second output path and switchable between a blocking voltage connection and the second biasing voltage connection such that when a second biasing voltage is applied to the second biasing voltage connection, and the first switch arrangement operably connects the blocking voltage connection, the second output path is deactivated and such that when a second biasing voltage is applied to the second biasing voltage connection and the first switch arrangement operably connects the second biasing voltage connection, the second output path is activated.
3. The amplifier of claim 2 , wherein the control port of the at least one amplifier of the first output path is operably connected to the second biasing voltage connection.
4. The amplifier of claim 1 , wherein the second output path further comprises:
a first transistor element having a control port and two signal connections, and wherein the output stage comprises:
a first switch arrangement, operably connected to the control port of the first transistor element of the second output path and switchable between the second biasing voltage connection and a blocking voltage connection such that when a second biasing voltage is applied to the second biasing voltage connection, and the first switch arrangement operably connects the blocking voltage connection, the first transistor element of the second output path is deactivated and such that when a second biasing voltage is applied to the second biasing voltage connection, and the first switch arrangement operably connects the second biasing voltage connection, the first transistor element of the second output path is activated.
5. The amplifier of claim 4 , wherein the first output path further comprises:
a first transistor element having a control port and two signal connections, the control port of the first transistor element of the first output path operably connected to the second biasing voltage connection.
6. The amplifier of claim 1 , wherein the at least one amplifier of the second output path comprises:
a control port;
a first signal connection operably connected to the input stage output; and
a second signal connection operably connected to the output stage output, and wherein the output stage further comprises:
a first switch arrangement connected to the control port of the at least one amplifier of the second output path and switchable between the blocking voltage connection and the second biasing voltage connection such that when a second biasing voltage is applied to the second biasing voltage connection, and the first switch arrangement operably connects the blocking voltage connection, the second output path is deactivated and such that when a second biasing voltage is applied to the second biasing voltage connection, and the first switch arrangement operably connects to the second biasing voltage connection, the second output path is activated.
7. The amplifier of claim 4 , wherein the second output path further comprises:
a second transistor element having a control port and two signal connections, and wherein the output stage comprises:
a second switch arrangement, operably connected to the control port of the second transistor element and switchable between the first biasing voltage connection and a blocking voltage connection such that when a first biasing voltage is applied to the first biasing voltage connection, and the second switch arrangement operably connects the blocking voltage connection, the second transistor element is deactivated and such that when a first biasing voltage is applied to the first biasing voltage connection, and the second switch arrangement operably connects to the first biasing voltage connection, the second transistor element is activated.
8. The amplifier of claim 7 , wherein the first output path comprises a second transistor element having a control port, the control port of the second transistor element of the first output path operably connected to the first biasing voltage connection.
9. The amplifier of claim 7 , wherein the at least one amplifier and the second transistor element of the second output path are operably connected in series between a first supply voltage connection and a second supply voltage connection, and wherein the blocking voltage connection is the second supply voltage connection.
10. The amplifier of claim 1 , wherein the at least one transistor element of the second input path comprises a control port, the amplifier further comprising:
a first switch arrangement, operably connected to the control port of the at least one transistor element of the second input path and switchable between the first biasing voltage connection and a blocking voltage connection such that when a first biasing voltage is applied to the first biasing voltage connection, and the first switch arrangement operably connects the blocking voltage connection, the at least one transistor element of the second input path is deactivated and such that when a first biasing voltage is applied to the first biasing voltage connection, and the first switch arrangement operably connects the first biasing voltage connection, the at least one transistor element of the second input path is activated.
11. The amplifier of claim 10 wherein the at least one transistor element of the first input path comprises a control port, the first biasing voltage connection operably connected to the control port of the at least one transistor element of the first input path.
12. The amplifier of claim 10 , wherein the at least one transistor element of the second input path is operably connected in series between the input and a second supply voltage connection, and wherein the blocking voltage connection is the second supply voltage connection.
13. The amplifier of claim 1 , wherein:
the at least one transistor element of the first input path comprises a first transistor;
the first input path further comprises a second transistor connected in series with the first transistor;
the at least one transistor element of the second input path comprises a first transistor;
the second input path further comprises a second transistor connected in series with the first transistor;
the first output path further comprises a first, a second, and a third transistor operably connected in series with the at least one amplifier of the first output path; and
the second output path further comprises a first, a second, and a third transistor operably connected in series with the at least one amplifier of the second output path.
14. The amplifier of claim 1 , wherein:
the at least one amplifier of the first output path comprises a first transistor;
the first output path further comprises a second transistor connected in parallel with the first transistor of the first output path;
the at least one amplifier of the second output path comprises a first transistor; and
the second output path further comprises a second transistor connected in parallel with the first transistor of the second output path.
15. The amplifier of claim 1 , wherein:
the amplifier is a fully differential amplifier;
the input of the input stage comprises a first and a second input terminal, the first and the second input terminal configured to receive differential input signals;
the first output path comprises a first differential output path operably connected the first input terminal and a second differential output path operably connected to the second input terminal;
the second output path comprises a first differential output path operably connected the first input terminal and a second differential output path operably connected to the second input terminal; and
the output of the output stage comprises a first and a second output terminal, the first and the second output terminals configured to receive amplified differential input signals from the first and second differential output paths respectively of the first and second output paths.
16. The amplifier of claim 15 , wherein the input stage comprises:
a first difference transistor operably connected to the first and the second input paths and having a control port, the control port comprising the first input terminal; and
a second difference transistor operably connected to the first and the second input paths and having a control port, the control port comprising the second input terminal.
17. The amplifier of claim 1 , further comprising:
a first activating means operable to connect the first biasing voltage connection to the at least one transistor element of the second input path in response to a first control signal and operable to disconnect the first biasing voltage connection from the at least one transistor element of the second input path in response to a second control signal;
a second activating means operable to connect the second biasing voltage connection to the at least one amplifier of the second output path in response to a first control signal and operable to disconnect the second biasing voltage connection from the at least one amplifier of the second output path in response to a second control signal; and
a controller operably connected to the first and the second activating means and operable to generate a first control signal for a first mode of operation and a second control signal for a second mode of operation.