APPARATUS AND METHOD FOR TRANSIMPEDANCE AMPLIFIERS WITH WIDE INPUT CURRENT RANGES
First Claim
1. A preamplifier circuit for converting an input current into an output voltage, the preamplifier circuit comprising:
- a first transimpedance amplifier receiving an input signal representing the input current and providing a first voltage output signal;
a second transimpedance amplifier matched to the first transimpedance amplifier and providing a second voltage output signal;
a biasing circuit providing first and second biasing currents to the respective first and second transimpedance amplifiers at least partially according to a reference current;
a reference circuit controlling the reference current provided to the biasing circuit at least partially according to an offset signal; and
an offset circuit providing the offset signal to the reference circuit according to a differential voltage output signal derived from the first and second voltage output signals.
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Accused Products
Abstract
Improved preamplifier circuits for converting single-ended input current signals to differential output voltage signals, including first and second transimpedance amplifiers with input transistors operating according to bias currents from a biasing circuit, output transistors and adjustable feedback impedances modified using an automatic gain control circuit, as well as a reference circuit controlling the bias currents according to an on-board reference current and the single-ended input or the differential output voltage signals from the transimpedance amplifiers.
25 Citations
20 Claims
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1. A preamplifier circuit for converting an input current into an output voltage, the preamplifier circuit comprising:
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a first transimpedance amplifier receiving an input signal representing the input current and providing a first voltage output signal; a second transimpedance amplifier matched to the first transimpedance amplifier and providing a second voltage output signal; a biasing circuit providing first and second biasing currents to the respective first and second transimpedance amplifiers at least partially according to a reference current; a reference circuit controlling the reference current provided to the biasing circuit at least partially according to an offset signal; and an offset circuit providing the offset signal to the reference circuit according to a differential voltage output signal derived from the first and second voltage output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An integrated circuit apparatus, comprising:
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a biasing circuit including first and second P-channel FETs with gate terminals coupled to one another, source terminals coupled to a voltage supply node, and drain terminals respectively providing first and second biasing currents according to a control voltage at the gate terminals; first and second transimpedance amplifiers individually comprising; an NPN input transistor including a collector terminal coupled to receive the first and second biasing currents from the biasing circuit through a corresponding resistor, and an emitter terminal coupled to a circuit ground node, the collector terminals of the input transistors providing a differential voltage output signal, an NPN output transistor with a base terminal connected to the collector terminal of the input transistor, and a collector terminal connected to the voltage supply node, and a feedback resistor connected between an emitter terminal of the output transistor and a base terminal of the input transistor; wherein the base terminal of the input transistor of the first transimpedance amplifier is connected to receive an input signal, and the transimpedance amplifiers provide the differential voltage output signal representing an amplitude of the input signal; and a reference circuit providing a reference current output to modify the control voltage provided to the biasing circuit to control the first and second biasing currents at least partially according to the differential voltage output signal and according to a reference current generated in the integrated circuit. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A preamplifier for converting a single-ended input current signal to a differential output voltage signal, comprising:
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a signal transimpedance amplifier including a first input transistor with a base terminal receiving the single-ended input current signal and a first output transistor; a dummy transimpedance amplifier matched to the signal transimpedance amplifier and including a second input transistor receiving no input signal and a second output transistor; wherein the signal and dummy transimpedance amplifiers provide the differential output voltage signal at least partially according to the single-ended input current signal and according to a biasing current source derived from a reference current source implemented within the preamplifier and an automatic gain control circuit output signal.
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Specification