High-gain amplifier having a limited output dynamic range
First Claim
1. An amplifier comprising a first and a second transistor arranged as a differential pair, each transistor having a bias terminal, a reference terminal connected to a current source and a transfer terminal connected to a supply terminal via a resistive branch, the bias terminals and the transfer terminals of the first and second transistors forming, respectively, a differential input and output, which are intended to receive and supply an input voltage and an output voltage respectively, a ratio between the values of the AC components of said voltages defining the gain of the amplifier, characterized in that the resistive branches of the first and second transistors have each at least one intermediate terminal between a first and a second resistive element arranged in series, and in that each resistive branch is provided with a first element which permits the conduction of a current controlled by the potential of its intermediate terminal to its associated transistor when the latter is conductive, and with a second element which permits the conduction of a current to the other transistor of the differential pair when said other transistor is conductive.
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Accused Products
Abstract
The present invention relates to an amplifier comprising two transistors (Q1,Q2) arranged as a differential pair. According to the invention, a switch system for switching current and splitting up resistive branches ensures, in the case of unbalance of the differential pair (Q1, Q2), the conduction of the current flowing through each resistive branch towards the one of the two transistors (Q1) or (Q2) that is conductive. The gain and the maximum value of the amplitude of the output voltage of such an amplifier may thus be adjusted independently of each other.
8 Citations
5 Claims
- 1. An amplifier comprising a first and a second transistor arranged as a differential pair, each transistor having a bias terminal, a reference terminal connected to a current source and a transfer terminal connected to a supply terminal via a resistive branch, the bias terminals and the transfer terminals of the first and second transistors forming, respectively, a differential input and output, which are intended to receive and supply an input voltage and an output voltage respectively, a ratio between the values of the AC components of said voltages defining the gain of the amplifier, characterized in that the resistive branches of the first and second transistors have each at least one intermediate terminal between a first and a second resistive element arranged in series, and in that each resistive branch is provided with a first element which permits the conduction of a current controlled by the potential of its intermediate terminal to its associated transistor when the latter is conductive, and with a second element which permits the conduction of a current to the other transistor of the differential pair when said other transistor is conductive.
Specification