Synchronous logarithmic amplifier

A logarithmic amplifier (50) comprising:

• a first channel including a plurality of N serially coupled amplifier stages (14A) each having an input and an output, wherein N is an integer greater than one, and wherein the input of a first amplifier stage forms a first channel input of the logarithmic amplifier;
• a second channel including a plurality of N serially coupled amplifier stages (14B) each having an input and an output, wherein the input of a first amplifier stage in the series of amplifier stages forms a second channel input of the logarithmic amplifier;
• a plurality of N multiplier stages (27) each having a first input coupled to the output of a corresponding amplifier stage in the first channel, a second input coupled to the output of a corresponding amplifier stage in the second channel, and an output;
• and
• summing means (24) having a plurality of inputs coupled to the outputs of each of the multiplier stages and an output forming a logarithmic amplifier output.

An amplification method comprising the steps of:

• providing a first amplifier channel including a plurality of N serially coupled amplifier stages (14A) each having an input and an output, wherein N is an integer greater than one, and wherein the input of a first amplifier stage forms a first channel input;
• supplying a first input signal to the first channel input;
• providing a second channel including a plurality of N serially coupled amplifier stages (14B) each having an input and an output, wherein the input of a first amplifier stage in the series of amplifier stages forms a second channel input;
• supplying a second input signal to the second channel input;
• multiplying a signal at the output of an amplifier stage in the first channel together with a signal at the output of a corresponding amplifier stage in the second channel to provide a plurality of N outputs;
• and
• summing the outputs of each of the multiplier stages to provide an output signal.