True Root-Mean-Square Detection with a Sub-Threshold Transistor Bridge Circuit
First Claim
1. A detector circuit comprising a sub-threshold transistor bridge circuit, each of the four branches of the bridge circuit comprising a transistor configured to operate in the sub-threshold region over a predetermined range of input signal levels so that 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, the bridge output signal having a low-frequency component substantially proportional to the squared-amplitude of the envelope of the input radio-frequency signal.
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Abstract
A sub-threshold transistor bridge circuit for use in detecting the signal level of an input radio-frequency signal is disclosed. In an exemplary embodiment each branch of the sub-threshold transistor bridge circuit comprises a transistor 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 an radio-frequency signal using a sub-threshold transistor bridge.
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Citations
12 Claims
- 1. A detector circuit comprising a sub-threshold transistor bridge circuit, each of the four branches of the bridge circuit comprising a transistor configured to operate in the sub-threshold region over a predetermined range of input signal levels so that 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, the bridge output signal having a low-frequency component substantially proportional to the squared-amplitude of the envelope of the input radio-frequency signal.
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8. A method of detecting a signal level of a radio-frequency signal, the method comprising:
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applying an input radio-frequency signal to a first pair of opposing corners of a sub-threshold transistor bridge circuit, each of the four branches of the bridge comprising a transistor configured to operate in the sub-threshold region over a predetermined range of input signal levels so that a bridge output signal at the remaining pair of opposing corners of the bridge has a low-frequency component substantially proportional to the squared-amplitude of the envelope of the input radio-frequency signal; and detecting a signal level for the input radio-frequency signal based on the bridge output signal. - View Dependent Claims (9, 10, 11, 12)
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Specification