Logarithmic amplifier comprising MESFET distributed amplifiers connected in cascade
OwnerColin S. Aitchisoninventor
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Abstract
Logarithmic amplifiers which have a logarithmic transfer characteristic are used, for example, in microwave instrumentation. Such an amplifier comprises a series of MESFET distributed amplifiers (DA1-DA8), each having a substantially linear transfer characteristic, connected in cascade. An input for the logarithmic amplifier is connected to an input end of the gate transmission line (G) of a first distributed amplifier (DA1) and the output end of the gate transmission line of each distributed amplifier is terminated by a demodulator (DM1-DM8) for demodulating amplitude modulation. Summing means (OP1) are connected to the output of each of the demodulators (DM1-DM8) to sum their outputs and thereby provide the output of the logarithmic amplifier.
Claims8
A logarithmic amplifier comprising:
- a series of MESFET distributed amplifiers connected in cascade, said MESFET distributed amplifiers having a substantially linear transfer characteristic,
- an input for said logarithmic amplifier being provided by an input end of a gate transmission line of a first distributed amplifier,
- demodulator means, said demodulator means being operatively connected to terminate said gate transmission line of each distributed amplifier, said demodulator means demodulating amplitude modulated signals, and,
- summing means operatively connected to each of said demodulator means, said summing means summing outputs of said demodulator means and thereby providing an output of said logarithmic amplifier.
Dependencies are inferred from the claim text.