Multiple multiplexer gain-ranging amplifier

Claim 2

A time-shared instantaneous gain-ranging amplifier system, comprising: 1. a plurality of channels, each channel including a. a preamplifier, b. a filter means operatively attached to said amplifier, and c. at least two gain-ranging multiplexers each having a single output and at least as many inputs between them to cover all channels, each of said gain-ranging multiplexer inputs being operatively connected to one of said filter means, said gainranging multiplexer being switchable between at least two gain positions in response to the output signal level of said gainranging multiplexer for each input channel connected thereto; 2. a second multiplexer means Having a plurality of inputs and a single output, each of said inputs being operatively connected to the output of one of said gain-ranging multiplexers, said second multiplexer means being adapted to sequentially connect each of said gain-ranging multiplexer outputs to the output of said multiplexer switch; 3. a sample and hold means connected to the output of said multiplexer; 4. an instantaneous gain-ranging amplifier connected to the output of said sample and hold means, said instantaneous gainranging amplifier having a plurality of cascaded 6 db gain stages, an output circuit and means for instantaneously connecting a given gain stage to said output circuit in response to the input signal level, whereby the output of said instantaneous gain-ranging amplifier remains within one digital bit of full scale on an analog-digital converter.

Claim 3

a second multiplexer means Having a plurality of inputs and a single output, each of said inputs being operatively connected to the output of one of said gain-ranging multiplexers, said second multiplexer means being adapted to sequentially connect each of said gain-ranging multiplexer outputs to the output of said multiplexer switch;

Claim 4

a second multiplexer means Having a plurality of inputs and a single output, each of said inputs being operatively connected to the output of one of said gain-ranging multiplexers, said second multiplexer means being adapted to sequentially connect each of said gain-ranging multiplexer outputs to the output of said multiplexer switch;

Claim 5

The apparatus of claim 1 wherein said gain-ranging multiplexer comprises: a plurality of inputs, a multiplexer means connected thereto for sequentially connecting each input to a single output channel of said multiplexer means; an operational amplifier having an input and feedback impedance, said feedback impedance being switchable between at least two impedance levels, the input to said operational amplifier means connected to the output of said multiplexer means; threshold detector means connected to the output of said operational amplifier means, and means for maintaining the output of said operational amplifier means below a predetermined level, said means being connected between said threshold means and said amplifier means.

Claim 6

The apparatus of claim 1 wherein: each input channel includes a pair of electrolytic capacitors connected in parallel; dc bias means connected thereto for minimizing the dc leakage current flowing therebetween.

Claim 7

a sample and hold means connected to the output of said multiplexer;

Claim 8

a sample and hold means connected to the output of said multiplexer;

Claim 9

an instantaneous gain-ranging amplifier connected to the output of said sample and hold means, said instantaneous gain-ranging amplifier having a plurality of cascaded 6 db gain stages, an output circuit and means for instantaneously connecting a given gain stage to said output circuit in response to the input signal level, whereby the output of said instantaneous gain-ranging amplifier remains within one digital bit of full scale on an analog-digital converter.

Claim 10

an instantaneous gain-ranging amplifier connected to the output of said sample and hold means, said instantaneous gain-ranging amplifier having a plurality of cascaded 6 db gain stages, an output circuit and means for instantaneously connecting a given gain stage to said output circuit in response to the input signal level, whereby the output of said instantaneous gain-ranging amplifier remains within one digital bit of full scale on an analog-digital converter.

Claim 11

The apparatus of claim 1 wherein said gain-ranging multiplexer comprises: a plurality of input channels; multiplexer means connected thereto for sequentially connecting each input channel to the output of said multiplexer means; gain-ranging amplifier means comprising a. a first operational amplifier having its inverting input connected to the output of said multiplexing means, said first operational amplifier having a feedback impedance switchable between at least two impedance levels; b. a second operational amplifier having its positive input connected to the output of said first operational amplifier, said second operational amplifier having a unity gain; c. means for detecting a threshold voltage and supplying an output signal in response thereto, said means having its input connected to the output of said first amplifier means; d. clock means for providing a series of output clock pulses in response to an enabling input signal, said input being connected to the output of said threshold detector whereby a string of output pulses are supplied by said clock means upon receiving a signal from said threshold detector; e. gain code logic means connected to the output of said clock means, said means having a plurality of stable states each corresponding to a particular impedance level and being switchable between states in response to signals from said clock means, said flip-flop means further having input means for independently setting the state thereof; f. means connected to said flip-flop means for setting the initial logic state thereof; g. decoder and switch driver means connected to the output of said flip-flop impedance level means for converting the digital output signal of said flip-flop means to an output signal on one of the output lines of said decoder and switch driver.