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True root-mean-square detection with a sub-threshold transistor bridge circuit

A bridge circuit, transistor technology, used in the field of detecting the power level or true root mean square level of radio frequency signals

Active Publication Date: 2011-07-13
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in some applications, even for complex waveforms where the relationship between the average level and the RMS level is unknown, a direct measurement of the RMS power may be desirable

Method used

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  • True root-mean-square detection with a sub-threshold transistor bridge circuit
  • True root-mean-square detection with a sub-threshold transistor bridge circuit
  • True root-mean-square detection with a sub-threshold transistor bridge circuit

Examples

Experimental program
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Embodiment Construction

[0020] figure 1 is a schematic diagram of a sub-threshold transistor bridge circuit 100 according to some embodiments of the invention. Bridge circuit 100 includes four branches, each branch including transistors configured to operate in the subthreshold region within a predetermined range of input signal levels. The gate of each transistor T101-T104 is DC coupled to the gate of the transistor on the opposite branch. Thus, gate G101 is coupled to G104, and gate G102 is coupled to G103. As will be explained in more detail below, at terminal V IN+ and V IN- An input radio frequency (RF) signal applied to bridge circuit 100 at a first pair of opposite corners produces a bridge output signal at the remaining pairs of opposite corners having a low frequency component approximately proportional to the squared amplitude of the envelope of the input RF signal.

[0021] Those skilled in RF circuit design will recognize that a subthreshold transistor bridge circuit has a topology so...

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PUM

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Abstract

A sub-threshold transistor bridge circuit (100) for use in detecting the signal level of an input radio-frequency signal (VIN+, VIN-) is disclosed. In an exemplary embodiment each branch of the sub-threshold transistor bridge circuit comprises a transistor (G101-G104) configured to operate in the sub-threshold region over a predetermined range of input signal levels. An input radio-frequency signal applied to a first pair of opposing corners of the bridge circuit yields a bridge output signal at the remaining pair of opposing corners that has a low-frequency component substantially proportional to the squared-amplitude of the envelope of the input radio-frequency signal. Also disclosed are various detector circuits including a sub-threshold transistor bridge circuit, as well as methods for detecting a signal level for a radio-frequency signal using a sub-threshold transistor bridge.

Description

[0001] The present invention relates generally to power detectors, and more particularly to detecting the power level or true root mean square level of radio frequency (RF) signals. Background technique [0002] Radio frequency detectors, which include devices capable of sensing voltage levels, current levels, or power levels of radio frequency (RF) signals, are used for a variety of purposes in radio applications. For example, an RF detector can be used to measure the output power of a transmitter power amplifier, or to estimate the signal strength of a received signal. [0003] A simple envelope detector might consist of only diodes and capacitors or a four diode bridge rectifier. Diodes used in power sensing applications are typically junction diodes (such as Schottky diodes) fabricated by standard CMOS process technology. These junction diodes exhibit large forward voltage drops and poor control operating parameters, limiting the dynamic range and accuracy of diode-based ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R21/10G01R19/04
CPCG01R17/16G01R21/10H04B17/0045H04B17/327
Inventor T·阿恩博格
Owner TELEFON AB LM ERICSSON (PUBL)