Amplifier, analogue to digital converter, methods of amplifying and of converting an analogue input signal to a digital output signal and of producing a mineral hydrocarbon fluid

1. An amplifier comprising:

an input signal node for conveying an input signal having an input signal value;

an output signal node for conveying an output signal having an output signal value;

amplifier circuitry coupled to the input signal node and provided with at least a first intermediate output signal node for conveying a first intermediate output signal having a first intermediate output signal value, and a second intermediate output signal node for conveying a second intermediate output signal having a second intermediate output signal value, whereby the first intermediate output signal value relates to the input signal value in accordance with a predetermined first signal gain and the second intermediate output signal value relates to the input signal value in accordance with a predetermined second signal gain, which predetermined second signal gain is at least ten times higher than the predetermined first signal gain; and

a signal selector arranged to select one of the intermediate output signals and to feed the selected one to the output signal node;

wherein the signal selector comprises an analogue comparator bank to compare the intermediate output signal values against reference values.

2. An amplifier comprising:

an input signal node for conveying an input signal having an input signal value;

an output signal node for conveying an output signal having an output signal value;

amplifier circuitry coupled to the input signal node and provide with at least a first intermediate output signal node for conveying a first intermediate output signal having a first intermediate output signal value, and a second intermediate output signal node for conveying a second intermediate output signal having a second intermediate output signal value, whereby the first intermediate output signal value relates to the input signal value in accordance with a predetermined first signal gain and the second intermediate output signal value relates to the input signal value in accordance with a predetermined second signal gain, which predetermined second signal gain is at least ten times higher than the predetermined first signal gain; and

a signal selector arranged to select one of the intermediate output signals and to feed the selected one to the output signal node;

wherein the signal selector comprises an analogue multiplexer that is electrically coupled to the first and second intermediate output signal nodes, and to the output signal node.

3. The amplifier of claim 1 , wherein the signal selector comprises a comparator bank and a priority encoder, the comparator bank having input lines and output lines, the input lines being electrically coupled to the first and second intermediate output signal nodes, and the output lines being coupled to the priority encoder.

4. The amplifier of claim 2 , wherein the signal selector further comprises a comparator bank and a priority encoder, the comparator bank having input lines and output lines of which the input lines are electrically coupled to the first and second intermediate output signal nodes, and of which the output lines are coupled to the priority encoder, wherein the priority encoder comprises an address output line, and whereby the multiplexer is arranged to select the intermediate output signal in accordance with the address represented on the address output line, and to feed the selected one to the output signal node.

5. An amplifier comprising:

an input signal node for conveying an input signal having an input signal value;

an output signal node for conveying an output signal having an output signal value;

amplifier circuitry coupled to the input signal node and provided with at least a first intermediate output signal node for conveying a first intermediate output signal having a first intermediate output signal value, and a second intermediate output signal node for conveying a second intermediate output signal having a second intermediate output signal value, whereby the first intermediate output signal value relates to the input signal value in accordance with a predetermined first signal gain and the second intermediate output signal value relates to the input signal value in accordance with a predetermined second signal gain, which predetermined second signal gain is at least ten times higher than the predetermined first signal gain; and

a signal selector arranged to select one of the intermediate output signals and to feed the selected one to the output signal node;

wherein the moduli of the first and second intermediate output signal values each are one of lower than, equal to, or higher than a maximum output value, and wherein the signal selector is arranged to select out of the intermediate output signals the one that has the highest value that is lower than or equal to the maximum output value.

6. The amplifier of claim 1 , the amplifier being incorporated in a down-hole tool.

7. The amplifier of claim 6 , whereby the down-hole tool comprises a receiver antenna and whereby the input signal node is coupled to the receiver antenna.

8. An analogue to digital converter, comprising

an input signal node for conveying an input signal having an input signal value;

an output signal node for conveying an output signal having an output signal value;

amplifier circuitry coupled to the input signal node and provided with at least a first intermediate output signal node for conveying a first intermediate output signal having a first intermediate output signal value, and a second intermediate output signal node for conveying a second intermediate output signal having a second intermediate output signal value, whereby the first intermediate output signal value relates to the input signal value in accordance with a predetermined first signal gain and the second intermediate output signal value relates to the input signal value in accordance with a predetermined second signal gain, which predetermined second signal gain is at least ten times higher than the predetermined first signal gain;

a signal selector arranged to select one of the intermediate output signals and to feed the selected one to the output signal node; and

analogue to digital conversion circuitry, coupled to at least the one output signal node, to convert the selected output signal

wherein the amplifier circuitry is coupled to sampled-and-hold circuitry which is switchable between a holding state and a releasing state in response to a pacer signal, and wherein the analogue to digital converter further comprises a pacer signal generator for activating the pacer signal.

9. Method of amplifying an input signal to generate an output signal, comprising the steps of:

conveying an input signal having an input signal value;

generating at least a first intermediate output signal having a first intermediate output signal value, by imposing predetermined first signal gain on the input signal;

generating at least a second intermediate output signal having a second intermediate output signal value, by imposing predetermined second signal gain on the input signal, which predetermined second signal gain is chosen at least ten times higher than the predetermined first signal gain;

selecting one of the first and second intermediate output signals as the output signal by:

comparing the first intermediate output signal to a reference value in an analogue comparator and issuing a first comparison result;

comparing the second intermediate output signal to a reference value in an analogue comparator and issuing a second comparison result;

selecting one of the intermediate output signals based on the first and second comparison results.

10. The method of claim 9 , wherein selecting one of the first and second intermediate output signals is done by continuously or repeatedly selecting one of the first and second intermediate output signals over time.

11. A method of producing a mineral hydrocarbon fluid from an earth formation, the method comprising steps of:

drilling a well bore in the earth formation;

generating an electromagnetic induction signal of the earth formation;

amplifying the electromagnetic induction signal to generate an output signal, employing the steps of:

generating at least a first intermediate output signal having a first intermediate output signal value, by imposing predetermined first signal gain on the electromagnetic induction signal;

generating at least a second intermediate output signal having a second intermediate output signal value, by imposing predetermined second signal gain on the electromagnetic induction signal, which predetermined second signal gain is chosen at least ten times higher than the predetermined first signal gain; and

selecting one of the first and second intermediate output signals as the output signal;

further processing the output signal to locate the mineral hydrocarbon fluid in the earth formation;

continuing drilling the well bore to the hydrocarbon fluid; and

producing the hydrocarbon fluid.