Internal power supply for amplifiers
AssigneeSemiconductor Components Industries, LLC
InventorAlexandra-Oana Petroianu
Life of this patent
Estimating the term…
Abstract
An internal power supply for an amplifier is disclosed. The internal power supply floats according to a common mode voltage at the input to the amplifier and according to an input voltage at an input stage of the amplifier. Powering the input stage of the amplifier using the floating supply allows for the use of low voltage devices even when the range of possible common mode voltages includes high voltages. The use of low voltage devices can correspond to performance improvement for the amplifier and can help reduce the size of the amplifier. The internal supply can accommodate both positive and negative common mode voltages and can be used for current sense amplifiers of any gain.
Claims19
A system comprising:
- an external power supply configured to generate a fixed voltage range defined by an upper external voltage (VDD) and a lower external voltage (VGND);
- an amplifier coupled to the external power supply and configured to receive an input signal that has a common-mode voltage (VCM) within a range of common-mode voltages, the amplifier including:
- a low-voltage (LV) core amplifier configured to amplify an input voltage (VIN), the LV core amplifier configured to operate at low voltages relative to the range of common-mode voltages;
- an internal power supply providing power to the LV core amplifier for operation, the internal power supply configured to generate a floating voltage range defined by an upper internal voltage (VINTP) and a lower internal voltage (VINTN), the floating voltage range level-shifted to VCM based on VIN so that an output of the LV core amplifier is in a first voltage range that corresponds to the floating voltage range, the internal power supply including a selector circuit configured to select a maximum voltage (VMAX) as the larger of the common mode voltage (VCM) and the upper external voltage (VDD) and a minimum voltage (VMIN) as the smaller of the common mode voltage (VCM) and the lower external voltage (VGND);
- and
- at least one output stage that is powered by the external power supply, the at least one output stage configured to level-shift the output of the LV core amplifier from the floating voltage range to a second voltage range that corresponds to the fixed voltage range.
A method for operating an amplifier that uses low voltage devices over a high voltage range of common mode voltages, the method comprising:
- receiving, at the amplifier, a fixed voltage range defined by an upper external voltage (VDD) and a lower external voltage (VGND);
- receiving a common mode voltage (VCM) at an input to the amplifier, VCM in a range of common mode voltages, the range common mode voltages including a positive voltage and a negative voltage;
- selecting a voltage maximum (VMAX) as the larger of the common mode voltage (VCM) and the upper external voltage (VDD) and a voltage minimum (VMIN) as the smaller of the common mode voltage (VCM) and the lower external voltage (VGND);
- and
- generating a floating voltage range to power an input stage of the amplifier, the floating voltage range level-shifted to VMAX or VMIN according to an input voltage (VIN) to an input stage of the amplifier.
An internal power supply for an amplifier that is configured to receive a range of common mode voltages that includes positive and negative voltages, the internal power supply comprising:
- a selector circuit configured to receive a common mode voltage (VCM) from an input to the amplifier and receive an upper external voltage (VDD) and a lower external voltage (VGND) from an external power supply, the selector circuit configured to select a maximum voltage (VMAX) as the larger of the common mode voltage (VCM) and the upper external voltage (VDD) and a minimum voltage (VMIN) as the smaller of the common mode voltage (VCM) and the lower external voltage (VGND);
- and
- a floating supply circuit configured to receive VMAX and VMIN from the selector circuit and input voltage (VIN) from a input stage of the amplifier, the floating supply circuit configured to generate a floating voltage range defined by an upper internal voltage (VINTP) and a lower internal voltage (VINTN), the floating voltage range level-shifted to VCM based on VIN.
Dependencies are inferred from the claim text.