Programmable gain attenuator for track and hold amplifiers
AssigneeBroadcom Corporation
InventorsOvidiu Bajdechi, Franciscus van der Goes
Life of this patent
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Abstract
A programmable gain attenuator (PGA) in particular to be used in a track-and-hold circuit is disclosed. The PGA is located in the feedback path around an operational amplifier. One tap switch is used to connect one PGA section to the output of the operational amplifier. The PGA section is capable of producing a multiplicity of different gain settings by using a multiplicity of secondary resistive devices in a voltage divider, wherein the resistive devices each can be independently coupled to a reference voltage.
Claims31
A programmable gain attenuator with an input (Vin) and an output (Vout) connector, wherein a gain rate is defined as the rate of the electric potential between the output connector and the input connector, comprising
- at least one voltage divider section with two resistive devices and a tap between them,
- wherein the voltage divider section is connected to the input connector with one end and to a reference voltage with its other end, and
- wherein the output connector is connected to the tap of the voltage divider section, and
- wherein the gain rate of the programmable gain attenuator is alterable by altering the value of the resistive device being located between the tap and the reference voltage.
A track-and-hold circuit comprising:
- an operational amplifier having a positive input connector, a negative input connector and an output connector, and
- a programmable gain attenuator (PGA) having an input connector being connected to the output of the operational amplifier and an output connector being connected to the negative input connector of the operational amplifier by means of a switch, the PGA comprising:
- at least one voltage divider section with two resistive devices and a tap between them,
- wherein the voltage divider section is connected to the input connector with one end and to a reference voltage with its other end and
- wherein the output connector is connected to the tap of the voltage divider section, and
- wherein the gain rate of the programmable gain attenuator is alterable by altering the value of the resistive device being located between the tap and the reference voltage.
A method for programming a programmable gain attenuator (PGA) circuit, wherein the PGA comprises an input connector and an output connector, the input connector of the PGA being connected to the output connector of an operational amplifier and the output connector of the PGA being connected to the negative input connector of the operational amplifier, comprising:
- supplying a reference potential to the PGA;
- closing at least one tap switch connecting the input connector of the PGA with a tap of a voltage divider section, wherein the voltage divider section is connected to the input connector by means of one resistive device;
- closing at least one switch connecting one of a plurality of resistive devices to the reference voltage.
Dependencies are inferred from the claim text.