TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure generally relates to the field of electronic circuits and, more particularly, to power detectors.

BACKGROUND

There are many applications in which it is desirable to measure the average power level of a radio frequency (RF) signal. For example, power measurement and control of RF signals in both the transmitting and receiving chains of modern wireless communications systems, such as cellular telephone networks, may be essential.

High dynamic range power detectors (e.g., those used to detect power greater than about 40 decibels (dB)) typically need to have a logarithmic response to be able to represent the entire dynamic range of input signals with a voltage level that can be used in practical systems. Such power detectors are called “logarithmic power detectors” (also commonly referred to as “log power detectors” or, simply, as “log detectors”). The mathematical relation between the input signal level and the output voltage of a log detector may be as follows:

VOUT=VY⁢log⁡(VINVX),
where VINis the input voltage, VOUTis the output voltage, VYis the logarithmic slope, and VXis the intercept, logarithm taken to the base of 10.

Log detectors can be used in a range applications such as transmit/receive power measurement in wireless communications systems, input protection, return loss measurement, pulse detection, electronic warfare, materials analysis, and medical applications. In general, log detectors can measure signal levels at frequencies from dc to microwave and provide a scaled dc output voltage which is proportional to the log of the input signal. High-frequency log detectors are essential is some applications (e.g., in wireless communications systems). Unfortunately, oftentimes high-frequency log detectors have significant noise that arises from the large bandwidth of input signals, e.g., up to tens of gigahertz (GHz), which may limit the detection dynamic range, elevate the minimum signal floor of the detector, and distort the log-linear characteristics.

